Method of separating acrylic acid, contained as main component, and glyoxal, contained as by-producer in gaseous mixture of products of partial heterogeniously catalysed vapour-phase oxidation of compound, acrylic acid precursor, containing 3 carbon atoms

FIELD: chemistry.

SUBSTANCE: invention relates to method of separating acrylic acid contained as main product, and glyoxal contained as by-product, in mixture of products of partial heterogeneously catalysed vapour-phase oxidation of acrylic acid precursor compound, which contains 3 carbon atoms, in which liquid phase P is obtained, which comprises acrylic acid to an extent of at least 70% of its weight, and, calculated for molar quantity of acrylic acid, contained therein, comprises at least 200 molar ppm of glyoxal, in which separation of glyoxal from acrylic acid is realised by crystallisation from liquid phase P.

EFFECT: method makes it possible to prevent undesirable polymerisation of acrylic acid.

25 cl

 

This invention relates to a method of separation of acrylic acid contained as a main product, and glyoxal contained as a by-product in the gaseous mixture of the products of partial heterogeneously catalyzed vapor-phase oxidation compounds, precursor of acrylic acid, containing 3 carbon atoms, which are the liquid phase P, which is at least 70% of its mass consists of acrylic acid, and also, in terms of molar quantity contained in acrylic acid, contains at least 200 mol. ppm glyoxal.

Acrylic acid is an important monomer which finds use as such and/or in the form of its complex alilovic esters for the production of polymers used in the field of hygiene (for example, super absorbent water) (see, for example, international application WO 02/055469 and WO 03/078378).

Obtaining acrylic acid can be carried out, for example, by heterogeneously catalyzed partial oxidation in the gas phase compounds predecessor, containing 3 carbon atoms (e.g. propylene, propane, acrolein, propionic aldehyde, propionic acid, propanol and/or glycerin), (see, for example, European patent application EP-A 990 636, application for U.S. patent US-A 5,198,578, European patent application EP-A 1015 410, EP-a 1 484 303, EP-a 1 484 308, EP-a 1 484 309, application for U.S. patent US-A 2004/0242826 and international application WO 2006/136336).

As a rule, in the framework of such a heterogeneously-catalyzed partial vapor oxidation is not pure acrylic acid, and only gaseous mixture of products containing acrylic acid which, in addition, acrylic acid also contains components that differ from acrylic acid, from which the acrylic acid has to be separated.

As far as the appearance and quantitative content in the gaseous mixture of product components, different from acrylic acid, among other things, can affect the purity to be used as feedstock connection predecessor, containing 3 carbon atoms, and the reaction conditions under which it is heterogeneously-catalyzed partial vapor-phase oxidation (cf., for example, German patent application DE-A 101 31 297 and DE-A 10 2005 052 917).

From European application EP-A 770 592 known that gaseous mixture of products of such a heterogeneously-catalyzed partial vapor oxidation, among other things, may contain as different from acrylic acid components of different aldehydes. Furthermore, from European application EP-A 770 592 known that the smallest amount of aldehyde impurities remaining in acrylic acid, m which may have significant adverse effects on the properties of acrylic acid. Thus, in accordance with the technical decision of the European patent application EP-A 770 592, a separate amount of aldehyde in the acrylic acid had to be in the region of less than 1 ppm, so that under the application of such acrylic acid, primarily in radical polymerization, for example, to get super absorbent polymers or polymers effective as a dispersing means for drilling fluids based on hydrocarbons or as coagulants, to achieve optimal product characteristics. To achieve this degree of separation, in European patent application EP-A 770 592 propose the combined use of aldehyde acceptors. However, the extra expense at the same time causes the disadvantages of the method proposed in this European patent application EP-A 770 592.

From European patent application EP-a 1 298 120 known that as a possible by-product of heterogeneously-catalyzed partial vapor oxidation compounds, the precursors to 3 carbon atoms to acrylic acid under certain conditions may also be formed aldehyde glyoxal. Among other things, and also due to the fact that glyoxal cause unwanted free-radical polymerization of acrylic acid, in European patent application EP-a 1 298 120 recommended so the project is activated obtaining acrylic acid, that the formation of glyoxal as a by-product is minimized (as a possible source of formation of glyoxal as a by-product within the heterogeneously-catalyzed partial vapor oxidation compounds, the precursors of acrylic acid, containing 3 carbon atoms, in European application EP-a 1 298 120, among others, set accidentally contained in the connection-the predecessor to 3 carbon atoms, an admixture of ethylene containing 2 carbon atoms).

With the additional use of the method of separation by reverse osmosis according to the European patent application EP-a 1 298 120 can be obtained gaseous mixture of products from which acrylic acid, also with the circulating absorbent agent can be transferred into the liquid phase, which contains less than 100 masses. ppm glyoxal. From the liquid phase of such acrylic acid, in accordance with the technical decision of the European patent application EP-a 1 298 120, then a relatively smooth can be separated using the method of separation by distillation. The disadvantage of this method of action, however, is the need for reverse osmosis, which reduces the volumetric efficiency.

In European patent application EP-a 1 396 484 proposed a method for the separation of acrylic acid contained as the main PR the product, and glyoxal contained as a by-product in the gaseous mixture of the products of partial heterogeneously-catalyzed vapor-phase oxidation of compounds, the precursors of acrylic acid, containing 3 carbon atoms, different from the method recommended in the European patent application EP-a 1 298 120, which allows a higher content of glyoxal as a side product (among other things, this is an advantage in that it allows the use of more economically attractive, with high concentration of impurity compounds, the precursors to 3 carbon atoms).

It differs in that the acrylic acid and glyoxal first absorbed from the gaseous mixture of products with an aqueous solution. And then the water from this solution is separated by azeotropic distillation (rectification). At the same time, to substantially suppress the undesirable formation of polymer, it is necessary to act so that the flow phlegmy had a certain water content, and reflux the number was not less than a certain value. In addition, you should maintain a certain temperature ratio.

Under these conditions, the applicability of glyoxal in the form of a high-boiling hydrate accumulates in the bottom of the column together with acrylic acid.

From above a bottom liquid is ti acrylic acid can then be separated from glyoxal hydrate distillation, moreover, these hydrates glyoxal, obviously, no longer possess the property of Monomeric glyoxal to cause unwanted radical polymerization of acrylic acid or, at least, have this property in a much smaller scale.

Own research of the applicant company have shown that the ability of glyoxal as impurities in the acrylic acid to cause a tendency of acrylic acid to undesired free-radical polymerization are much stronger in comparison with other aldehydes of adverse reactions in heterogeneously catalyzed partial vapor-phase oxidation of compounds, the precursors containing 3 carbon atoms (such as, for example, acetaldehyde, formaldehyde, Propionaldehyde, benzaldehyde, Butyraldehyde, acrolein), in terms of the same molar content of impurities. In all likelihood, this is because, as proved by the results of quantum-mechanical calculations of the energies of dissociation, on the one hand, thermal costs cleavage of Monomeric glyoxal two formyl radical are particularly small, and, on the other hand, the resulting formyl radicals much reaktsionnosposobnykh than, for example, a radical of hydrogen or a methyl radical (calculation method CCSD(T) method associated cluster is in single, two- (and three -) excitations, eng. Coupled Cluster including Single, Double and Triple excitations)).

Experiments in conjunction with surveys in the literature (for example, L actualite chimique, Mai 1982, pages 23 to 31, and also cited in this publication, the literature has shown that glyoxal hydrates are not above a strong effect monomer (molecular) glyoxal, causing polymerization.

This glyoxal hydrates form two groups of varieties hydrates. The first group consists of Monomeric glyoxal monohydrate and of Monomeric glyoxal dihydrate:

Both these glyoxal hydrate are formed at relatively mild conditions (low temperature, low content of water is sufficient).

However, the response of education as Monomeric glyoxal monohydrate and Monomeric glyoxal dihydrate is pronounced reversible reaction. That is, although each of both of the above hydrates are no longer possesses a strong ability Monomeric glyoxal to cause polymerization, however, both of these hydrates, for example, when a small temperature increase can again be formed of Monomeric glyoxal, which is then in the condition known to contribute to undesired free-radical polymerization of acrylic acid is you. Thus, in the future, as well as generally throughout this publication (excluding the introductory part), standing separately, the term "glyoxal" all the time should include the total number consisting of Monomeric glyoxal, Monomeric glyoxal monohydrate and Monomeric glyoxal dihydrate.

Therefore, on the background of the foregoing, for the successful execution of the technical solution described in European patent application EP-a 1 396484, the formation of Monomeric glyoxal monohydrate and/or Monomeric glyoxal dihydrate in a distillation column under azeotropic distillation is insufficient, these hydrates are also generally have higher boiling point and normal mode are accumulated together with acrylic acid in the lower part of the column.

Moreover, for successful implementation of the method of conducting the process recommended in European patent application EP-a 1 396 484, in accordance with their own research, it is necessary the formation of hydrates "polyglycol" or "oligosiloxane". They form the second group glyoxal hydrates. In the examples should lead diglycol hydrate, tropical hydrate:

or

Diglycol hydrate

or

TRIG is yoxall hydrate

Presumably the formation of polyglycol hydrates flows through the intermediate stage of glyoxal dihydrate.

In contrast to the formation of Monomeric glyoxal hydrate, education, polyglycol hydrates requires elevated temperatures (usually their education in a significant volume takes place only at temperatures above 50°C) and/or longer reaction time. As well as Monomeric glyoxal hydrates, polyglycol hydrates no longer have the usual Monomeric glyoxal effect in respect of acrylic acid to cause polymerization or, at least, have this property in a much smaller scale than he. However, in contrast to the formation of Monomeric glyoxal hydrates, the formation of polyglycol hydrates occurs largely irreversible (at least under the same conditions, which are usually used for separating acrylic acid from a mixture of products heterogeneously catalyzed partial vapor oxidation compounds, the precursors of acrylic acid, containing 3 carbon atoms).

Thus, the successful application of the methodology recommended in the European patent application EP-a 1 396484 is reproducible only on the basis of education polyglycol hydrates. However, this requires that is a shortcoming of the way stand the high temperatures, and increased interaction time.

Thus, the objective of the invention was to provide improved with respect to the process, which is the closest analogue of the prior art, the method of separation of acrylic acid contained as a main product in a gaseous mixture of products of partial heterogeneously catalyzed vapor-phase oxidation of compounds, the precursors of acrylic acid, containing 3 carbon atoms, and glyoxal contained as a by-product that basically no longer have the described disadvantages of the methods of the prior art and, in particular, does not require education polyglycol hydrates.

Accordingly, we propose a method of separation of acrylic acid contained as a main product in a gaseous mixture of products of partial heterogeneously catalyzed vapor-phase oxidation compounds, precursor of acrylic acid, containing 3 carbon atoms, and glyoxal contained as a by-product, which are the liquid phase P, which is at least 70% of its mass consists of acrylic acid, and also, in terms of the number contained in acrylic acid, contains at least 200 mol. ppm glyoxal (by this publication, as already mentioned,understand the total number, consisting of Monomeric glyoxal, Monomeric glyoxal monohydrate and Monomeric glyoxal dihydrate), which is characterized by the fact that the Department of glyoxal from acrylic acid from the liquid phase P is carried out by crystallization, and acrylic acid accumulates in the formed product of crystallization, and glyoxal in the mother solution, the remaining crystallization.

The advantage of the method according to the invention, on the one hand, justified by the fact that it does not require or does not involve restrictions on the number of education glyoxal as a by-product, and, on the other hand, the fact that it does not require the formation of hydrates of polyglycolic.

In addition, it was unexpectedly found that the enrichment factor for glyoxal AndGlyaccompanying crystal separation according to the invention, as a rule, reaches values in excess of ten thousand (>>10000).

Under the enrichment factor And, as a rule, understand the relationship between the number of impurities remaining in the mother solution, and impurities remaining in the product crystallization (respectively, expressed as % of the mass. in terms of the total amount of mother liquor or respectively the total number of product crystallization; for example, by centrifugation or by centrifugation and/or washing m is the exact solution and the product crystallization can basically completely separate from each other, but through further analysis to determine the enrichment factor A; for this, as a rule, it is sufficient separation of the mother liquor more than 90 wt. -%, preferably more than 95, or 97, or 98, or 99% of the mass. from the total number).

Under appropriate crystallization separation no other possible unwanted side product heterogeneously catalyzed partially oxidizing get in the gas phase of acrylic acid from its compounds, the precursors containing 3 carbon atoms, does not attain the value And comparable order.

This circumstance is all the more remarkable that the magnitude AndGlycovers not only the crystallization separation of Monomeric glyoxal, and crystallization separation of Monomeric glyoxal, Monomeric glyoxal monohydrate and Monomeric glyoxal dihydrate (compare with the definition of standing separately of the term "glyoxal").

The above experimental results reveal the possibility of separating from the liquid phase P in the process of obtaining, for example, suitable for super absorbent purposes of pure acrylic acid, preventing such use glyoxaline impurities in a satisfactory manner for one stage of separation in a single stage crystallization.

The unit "mol. ppm" (molar millions of dollars which should be understood as meaning, what if a certain amount of liquid phase P contains, for example, 1 mol of acrylic acid, and the same amount of liquid phase P at the same time contains 10·10-6mol of glyoxal, the amount of liquid phase P, in terms of the contained molar amount of acrylic acid contained 10 mol. ppm glyoxal.

That is, the method according to the invention can also be applied with success in the case, if the liquid phase P, which is at least 70% of its mass consists of acrylic acid, in terms of the contained molar amount of acrylic acid, contains ≥ 250 mol. ppm or ≥ 300 mol. ppm, or ≥ 400 mol. ppm, or ≥ 500 mol. ppm, or ≥ 750 mol. ppm, or ≥ 1000 mol. ppm, or ≥ 1250 mol. ppm, or ≥ 1500 mol. ppm glyoxal (which in this publication represents the total number consisting of Monomeric glyoxal, Monomeric glyoxal monohydrate and Monomeric glyoxal dihydrate).

Typically, the liquid phase P, which is at least 70% of its mass consists of acrylic acid, in terms of the contained molar amount of acrylic acid, contains ≤ 5 mol%, often ≤ 2 mol%. or ≤ 1 mol%. glyoxal. It goes without saying that the method according to the invention can also be successfully used even in the case of the above-mentioned content of glyoxal.

But the way solenoidoperated can also be used successfully for all (that is, each individual named above) individually listed in this publication contents glyoxal in the liquid phase P (respectively, given in mol. ppm, calculated on the molar amount of acrylic acid contained in this liquid phase P), if this liquid phase P comprises acrylic acid by the value of ≥ 75% of the mass. or ≥ 80 wt. -%, or ≥ 85 wt. -%, or ≥ 90 wt. -%, or ≥ 95 wt. -%, or ≥ 96% of the mass, or ≥ 97 wt. -%, or ≥ 98 wt. -%, or ≥ 99% of the mass. (respectively by weight of this liquid phase P).

The content of glyoxal in the liquid phase P, which should be treated according to the invention (or other liquid), (i.e., the total content in the liquid phase P Monomeric glyoxal, Monomeric glyoxal monohydrate and Monomeric glyoxal dihydrate) in this publication is defined as follows:

First prepare a solution for deriving D. For that 2.0 g of a 50%aqueous solution of 2,4-dinitrophenylhydrazine (manufacturer: Aldrich, purity: ≥ 97%) at a temperature of 25°C dissolved in 62 ml of aqueous hydrochloric acid with a concentration of 37% of the mass. (manufacturer: Aldrich, purity: ≥ 99.999%availability). The resulting solution is then (also at 25°C) was added with stirring to 335 g of distilled water. After stirring for 1 hour at 25°C. using a filter gain in the form of the resulting filter is the solution for deriving D.

For the determination of glyoxal in the liquid phase P 1 g of the solution to obtain the derivative D (if necessary, this amount can be appropriately increased) is weighed into a glass jar with a screw top, the capacity of which amounts to 10 ml and Then filled in so the glass jar with screw-on lid additionally weighed sample of the liquid phase P, the number of which lies in the range of from 0.15 to 2.0,

Then by shaking the entire contents of this glass jars with screw-on lid is stirred and then left to stand without intervention at 25°C for a time of 10 minutes. During this time of Monomeric glyoxal contained in this glass jar with a screw top, by a chemical reaction with 2,4-dinitrophenylhydrazine is formed corresponding hydrazone Monomeric glyoxal N. However, during this 2,4-dinitrophenylhydrazine also in the form of a hydrazone N extracts from Monomeric glyoxal monohydrate and glyoxal dihydrate contained in this glass jar with a screw cap and associated them Monomeric glyoxal (and Vice versa, the corresponding extraction of Monomeric glyoxal from hydrates of polyglycolic contained in this glass jar with a screw top, not PR is coming).

Then by adding in this glass jar with a screw cap 0.5 g of glacial acetic acid (manufacturer: Aldrich, purity: ≥ 99.8 per cent) occurred hydrazone formation is frozen. If adding glacial acetic acid is accompanied by the formation of a solid precipitate, then gradually add glacial acetic acid to re-dissolve this precipitate formed (however, the total amount of added glacial acetic acid may not exceed 1 year). If the precipitate is not dissolved and upon reaching the upper boundary (1.0 g) valid total number of added glacial acetic acid, then add 0.5 g of dimethylphthalate. If this does not help to dissolve the precipitate, add the number of dimethylphthalate gradually increase to contribute to this dissolution (however, the total amount of the added dimethylphthalate may not exceed 1 year). If the sediment is also not dissolved upon reaching the upper boundary (1.0 g) valid total number add dimethylphthalate, then add 2 g of the mixture G consisting of 9 g of acetonitrile and 1 g of dimethylphthalate. If this addition does not help to dissolve the precipitate, then the added amount of the mixture G is gradually increased, in order to contribute to this dissolution. Obichnoie the number of added mixture G, in order to achieve dissolution of the sludge does not exceed 5 g (all of the above experiments on the dissolution is conducted at 25°C).

After this, the solution of the hydrazone N, obtained as described in a glass jar with a screw top, examine the content of the hydrazone by the method of HPLC (high performance liquid chromatography under high pressure, eng. HPLC (High Pressure Liquid Chromatography)) under the following operating conditions (molar quantities directly obtained molar quantity of glyoxal contained in the liquid phase P):

used chromatographic column:Waters Symmetry C18, 150×4.6 mm,
5 µm
(Waters Associates, Mil-Ford, mA, USA);

The volume of solution injected,the
subject analysis:50 μl (time t=0);
Temperature:40°C;
The flow rate of eluent:1.5 ml/min;
Duration analysis:17 min;
The equilibrium times:8 min;

Eluent:time interval from t>0 min to 15 min, a mixture of 30% of the mass. acetonitrile, 50% of the mass. water I% of the mass. tetrahydrofuran (respectively qualification "HPLC");
time interval from > 15 min to 17 min a mixture of 65% of the mass. acetonitrile, 30% of the mass. water and 5% wt. tetrahydrofuran;
time interval from > 17 min to 25 min, a mixture of 30% of the mass. acetonitrile, 50% of the mass. water and 20% of the mass. tetrahydrofuran (then in column establishes the equilibrium, and it is again ready for the next analysis).

The retention time of glyoxal in the form of a hydrazone N when the above conditions is 7,613 minutes

This analysis is carried out using monochromatic radiation with a wavelength of 365 nm. As the method of analysis used absorption spectroscopy. Change of eluent for elution process provides improved separation efficiency (typically, the liquid phase P, in addition to glyoxal, contains more poboc the haunted aldehyde products and/or by - products ketones, which in each case form the corresponding hydrazones with 2,4-dinitrophenylhydrazine).

For calibration of the HPLC method applied purposes it is advisable to use a solution of Monomeric glyoxal in methanol, which contains 50 mol. ppm Monomeric glyoxal.

For this purpose, it is, as described above, is treated with a solution to obtain the derivative D, and then subjected to the specified analysis by HPLC method.

The method according to the invention, among other things, has to imagine that, as already mentioned, he dispenses with the use of high purity compounds, the precursors of acrylic acid, containing 3 carbon atoms, for heterogeneously-catalyzed partial vapor oxidation to obtain this acrylic acid.

For example, it is heterogeneously-catalyzed partial vapor oxidation to obtain acrylic acid can be applied to the original gaseous reaction mixture, which, in terms of the contained molar amount of the compounds, the precursors to 3 carbon atoms (for example, propane, propylene, acrolein, propionic acid, Propionaldehyde, propanol and/or glycerol), contains the total molar amount of compounds having 2 carbon atoms (for example, ethane, ethylene, acetylene, ACET is legido, acetic acid and/or ethanol), equal to ≥ 200 mol. ppm or ≥ 250 mol. ppm, or ≥ 300 mol. ppm, or ≥ 400 mol. ppm, or ≥ 500 mol. ppm, or ≥ 750 mol. ppm, or ≥ 1000 mol. ppm, Il ≥ 1250 mol. ppm, or ≥ 1500 mol. ppm

The original gaseous reaction mixture is the same gaseous mixture, which is fed through the catalyst bed to ensure partial oxidation to acrylic acid contained therein connection predecessor to 3 carbon atoms. In addition to the connection predecessor, containing 3 carbon atoms, undesirable impurities and molecular oxygen as oxidant, this source of gaseous reaction mixture, usually contains an inert gas diluent such as, for example, N2, CO2N2O, noble gas, molecular hydrogen, etc. Each inert razvivalisi gas usually has such properties that in the process of passing this heterogeneously catalyzed partial oxidation it remains unchanged for at least 95 mol%. from your original number.

The proportion of compounds of the precursor containing 3 carbon atoms, in the original gaseous reaction mixture may be within, for example, from 4 to 20% vol. or from 5 to 15% vol., or from 6 to 12% vol.

Typically, this source of gaseous reaction mixture, in terms of the stoichiometry of the reaction is AI partial oxidation connection predecessor containing 3 carbon atoms, to acrylic acid, contains an excess of molecular oxygen, in order to again be subjected to re-oxylene, typically, an oxide catalysts.

This excess in the case of subsequent applications of the method of implementation according to the invention may be chosen especially great, because with increasing excess oxygen, as a rule, also a simultaneous increase in the undesired formation of by - product-glyoxal.

Similarly, when heterogeneously-catalyzed partial vapor oxidation compounds, precursor of acrylic acid, containing 3 carbon atoms, can be selected relatively high maximum temperature existing in the layer of catalyst, if at the end of this partial oxidation is applied the method according to the invention. Among other things, this is due to the fact that when increasing the maximum temperature, as a rule, also a simultaneous increase in the undesired formation of by - product-glyoxal. However, the use of higher maximum temperatures, as a rule, allows the use of catalysts with lower activity, which opens up the possibility of increased service life of the catalyst. However, when using catalysts with low activity in trustusa degrees of transformation connection predecessor containing 3 carbon atoms, an increasing amount often is unwanted full oxidation. If necessary as an intermediate product can also be formed glyoxal.

Similarly, in accordance with the method according to the invention it is also possible to conduct the process in a wide range of selection pressures on the layer of catalyst compound-precursor containing 3 carbon atoms. In addition, it was found that the formation of by-product - glyoxal contributes to the high content in the reaction gas mixture of water vapor. Therefore, the method according to the invention not least is important in the case when the source of the gaseous reaction mixture used for the heterogeneously catalyzed partial vapor oxidation connection predecessor, containing 3 carbon atoms, includes ≥ 1% of the mass. or ≥ 2% wt., or ≥ 3 wt. -%, or ≥ 4 wt. -%, or ≥ 5 wt. -%, or ≥ 7% wt., or ≥ 9 wt. -%, or ≥ 15 wt. -%, or ≥ 20% of the mass. water vapour. Typically, however, the water vapor content in the original gaseous reaction mixture is not more than 40 wt. -%, often no more than 30% of the mass.

Otherwise, the process heterogeneously-catalyzed partial vapor oxidation to obtain acrylic acid can be carried out by known who tym ways so as described in the prior art.

If in the case of compounds, the precursors to 3 carbon atoms we are talking about, for example, propylene and/or acrolein, it is heterogeneously catalyzed partial vapor-phase oxidation can be carried out, as described, for example, in publications such as international patent application WO 2005/042459, WO 2005/047224 and WO 2005/047226.

If the connection is a predecessor to 3 carbon atoms is, for example, propane, heterogeneously catalyzed partial vapor oxidation to obtain acrylic acid can be carried out, as described, for example, in publications such as European application EP-A 608 838, German patent application DE-A 198 35 247, DE-A 102 45 585 and DE-A10246119.

If the connection is a predecessor to 3 carbon atoms is, for example, glycerin, heterogeneously catalyzed partial vapor oxidation to obtain acrylic acid can be carried out, as described, for example, in publications such as international patent application WO 2007/090991, WO 2006/114506, WO 2005/073160, WO 2006/114506, WO 2006/092272 or WO 2005/073160.

Also already been proposed to obtain propylene as a connection-predecessor to 3 carbon atoms preceded by partial vapor-phase oxylene preliminary partial dehydrogenation and/or oxidisation propane (such as international announced the Ah WO 076370, WO 01/96271, European patent application EP-A 117146, international applications WO 03/011804 and WO 01/96270).

For separating acrylic acid from a gaseous mixture of products heterogeneously-catalyzed partial vapor oxidation compounds, the precursors to 3 carbon atoms is usually used a combination of different methods of separation, so that more cost-effective way to achieve purity of acrylic acid, corresponding to the purpose of its further use. When this combination is used in a particular case, not in the last turn depends on the type and quantity different from the acrylic acid of the various components contained in a gaseous mixture of products. Thus, obtain the liquid phase P, which can be treated according to the invention may be carried out in a variety of ways.

An important component of this combination of methods of separation are usually not thermal crystallization methods of separation. These are not thermal crystallization methods of separation are the ways in which the separating columns containing internal elements contributing to the division serves a countercurrent gaseous (ascending) and liquid (descending) flows substances or respectively two streams of liquid substances, and following the journey of emerging between threads substances gradients is heat and mass transfer, which, ultimately, makes the specified separation in the separation column.

Examples of such non-crystallization thermal methods of separation are (partial) condensation, fractional condensation (see German patent application DE-A 199 24 532), as well as rectification.

The resulting separating action in this case is based primarily on differences in the boiling points of acrylic acid and side components, different from acrylic acid. Another example is the absorbance. In this case, the separating action is based primarily on the different solubility in the absorbent liquid of acrylic acid and side components, different from acrylic acid. The above also applies to non-thermal crystallization method of separation by distillation (to remove gas captures from the liquid components with different affinity, it contains in dissolved form)and desorption (the reverse process of absorption; the substance dissolved in the liquid phase is separated by means of lowering the partial pressure). However, the term "thermal methods of separation" also includes azeotropic distillation or rectification (they use different distinct tendency to the formation of azeotropes with added agents forming azeotrope, by the tea acrylic acid and in the case of side components (components in the gaseous reaction mixture, different from acrylic acid). In addition, the term "thermal methods of separation" includes the extraction.

Hallmark, basically, which is common to all possible combinations of thermal methods of separation of acrylic acid from a gaseous mixture of products heterogeneously catalyzed partial vapor oxidation compounds, the precursors to 3 carbon atoms, is that, if necessary, after direct and/or indirect cooling of the above-mentioned gaseous mixture of products, acrylic acid contained in the gaseous mixture products on the main stage separation means in condensed matter (in particular, liquid) phase (from which, in the framework of this basic separation, the residual gas, the remaining gas from the point of view of technical feasibility, least partially fed back into the process of partial heterogeneously catalyzed vapor-phase oxidation of compounds of the predecessor to 3 carbon atoms (for example, in the original gaseous reaction mixture for this oxidation) as a circulating gas (the mode with the management of gas"); typically, this residual gas (circulating gas) consists largely of inert gaseous diluents used in conjunction with partial heterogeneously-catalyzed vapor-Oka is making connections-predecessor to 3 carbon atoms, and water vapor, usually formed as a by-product of this partial oxidation, and by-products produced by complete oxidation of unwanted compounds predecessor to 3 carbon atoms (e.g., carbon dioxide), which may also contain glyoxal; if the primary separation stage represents the absorbance, this circulating gas may also contain absorbent; partly it still contains minor amounts of neisrashodovannoe in partial oxidation of molecular oxygen (residual oxygen) and/or unreacted organic compound, the precursor to 3 carbon atoms (see, for example, international application WO 2004/007405 and the German patent application DE-A 102007019597)).

This can be done, for example, by absorption in a suitable solvent (e.g. water, high-boiling organic solvent, aqueous solutions) and/or partial or mostly full condensation (for example, fractional condensation) (see, for example, published European patent applications EP-A 13 88 533, EP-A 13 88 532, German patent application DE-A 102 35 847, European application EP-A 79 28 67, international application WO 98/01415, European application EP-A 10 15 411, EP And 10 15 410, the international application WO 99/50219, WO 00/53560, WO 02/09839, German application DE - a 102 35 847, international application WO 03/041833, German application DE-A 102 23 058, DE-A 102 43 625, DE-A 103 36 386, European application EP-85 41 29, application for U.S. patent US-A 4,317,926, German application DE-a 198 37 520, DE-A 196 06 877, DE-A 190 50 1325, DE-A 102 47 240, DE-A 197 40 253, European application EP-A 69 57 36, EP-98 22 87, EP-10 41 062, EP-A 11 71 46, of German application DE-A 43 08 087, DE-A 43 35 172, DE-A 44 36 243, DE-A 19 924 532, DE-A 103 32 758, and also DE-A 19 924 533). Department of acrylic acid can also be produced as described in European patent applications EP-98 22 87, EP-98 22 89, of German application DE-A 103 36 386, DE-A 101 15 277, DE-A 196 06 877, DE-A 197 40 252, DE-A 196 27 847, European applications EP-A 92 04 08, EP-A 10 68 174, EP-10 66 239, EP-10 66 240, international applications WO 00/53560 WO 00/53561, German application DE-A 100 53 086, and European application EP-98 22 88. Suitable methods of separation are also the methods described in the publications of international applications WO 2004/063138, WO 2004/035514, German patent applications DE-A 102 43 625 and DE-A.

Other stages of separation, which should be used to highlight acrylic acid, the desired degree of purity of the liquid (or, generally, condensed) phase containing the target product is acrylic acid, and obtained in the framework of this main division, depending on the planned objectives can be very different combinations of adsorption, extraction, desorption, using distillation, distillation, rectification, azeotropic the Yu distillation, azeotropic rectification, and crystallization methods.

If the liquid phase P passes through this phase, or liquid phase, resulting in the framework described main phase separation containing the target product is acrylic acid, is already in the liquid phase P, then it is preferable for the Department of glyoxal contained in this liquid phase P, can be applied to the method according to the invention. The fact that when using the method according to the invention for the liquid phase P (that is, by cooling the liquid phase P) regularly distilled acrylic acid, due to the high required minimum content of acrylic acid. It may be, as has been said, for example, ≥ 70 and ≤ 99,5% of the mass. or ≥ 80 ≤ 99,5% of the mass, or ≥ 85 to ≤ 99 wt. -%, or ≥ 90 and ≤ 98 wt. -%, or ≥ 93 to ≤ 97% of the mass.

The method of crystallization according to the invention can be carried out in the same manner and integrated in the same way in the General process of allocation (net) acrylic acid from a gaseous mixture of products heterogeneously catalyzed partial vapor oxidation connection predecessor to 3 carbon atoms, as shown in particular in the following publications from the prior art: the international application WO 02/055469, WO 03/078378, WO 01/77056, WO 03/041833, German patent application DE-A 196 06 877, DEA 103 36 386, international application WO 98/01414, WO 01/77056, European patent application EP-a 1 484 308, EP-a 1 484 309, application for U.S. patent US-A 2004/0242826, German application DE-A 102 43 625, DE-A 196 06 877, European application EP-A 792 867, EP-a 1 015 410, EP-920 408, EP-a 1 189 861, EP-a 1 015 411, EP-a 1 068 174, the international application WO 2004/035514, European application EP-a 1 066 293, EP-a 1 163 201, EP-a 1 159 249, international application WO 02/090310, German application DE-A 101 22 787, international application WO 03/041832, German application DE-A 102 35 847, European application EP-a 1 252 129, EP-A 616 998, EP-a 1 388 533, EP-a 1 125 912, and EP-A1 116709.

Especially great is the method according to the invention is when from a gaseous mixture of products heterogeneously catalyzed partial vapor-phase oxidation of at least one compound is a precursor of acrylic acid, containing 3 carbon atoms, the liquid phase P, containing acrylic acid as the main product, and glyoxal as a by-product, which must be processed in accordance with the invention, is obtained by applying at least one crystallization thermal separation processes. First and foremost, when the mother liquor remaining in the crystallization separation according to the invention glyoxal contained in the liquid phase P (which in this case is enriched in content of glyoxal), return back at m the re in one of the crystallization thermal methods of separation, used to get this liquid phase P.

On this basic structure is similar to the combined application of non-crystallization thermal methods of separation and crystallization methods of separation indicate, for example, in German patent application DE-A 196 06 877, European applications EP-A 792 867, and EP-a 1 484 308, EP-a 1 484 309, EP-a 1 116 709 and, above all, EP-a 1 015 410.

The method according to the invention in the case of this combination is more important, since continuous method of operation by this method in the liquid phase P, which should be treated according to the invention, due to return back to the mother liquor increases the level of glyoxal, because this mother solution (as already mentioned) enriched in content of glyoxal. That is, a relatively low value content of glyoxal in the gaseous mixture of the products of the vapor-phase oxidation thus can also become a serious problem (from original non-liquid phase P (which initially contains less than 200 mol. ppm of glyoxal, in terms therein molar amount of acrylic acid) during continuous operation the liquid phase P, which should be treated according to the invention (which then contains at least 200 mol. ppm of glyoxal, in terms of contained is it the molar amount of acrylic acid), it may happen only under certain conditions). Enrichment factor AndGlygreater than the average value in such cases is mandatory for the successful implementation of the method.

However, the high content of glyoxal in the liquid phase P, is required according to the invention, may be it also, for example, in the case where crystallization of the liquid phase containing acrylic acid, which have only a lower content of glyoxal, the resulting uterine solutions are again subjected to crystallization to increase output, or when no crystallization thermal separations are generated in the process of obtaining pure acrylic acid flows adverse substances, optionally containing impurities according to the invention, the process according to the invention to increase output.

Because heterogeneously catalyzed partial vapor-phase oxidation of compounds, the precursors to 3 carbon atoms, water, as a rule, necessarily formed as a by-product, and optionally, is used as the inert dilution gas in the gaseous reaction mixture, the liquid phase P, which should be treated according to the invention often contains not only water, but at the same time, in addition to Monomeric g is Oksala, also Monomeric glyoxal monohydrate and Monomeric glyoxal dihydrate. However, in many cases in the liquid phase P, which should be treated according to the invention can also contain only Monomeric glyoxal (the advantage of the method according to the invention, among others, also lies in the fact that it has efficacy in both cases).

That is, the method according to the invention can also be used, in particular, when glyoxal is contained in the liquid phase P, is present in the liquid phase P (or, respectively, contained in this liquid phase P) in the form of Monomeric glyoxal monohydrate and/or Monomeric glyoxal dihydrate in an amount of at least 30 mol%. or at least up to 50 mol%, or at least 70 mol%, or at least 90 mol%, or at least to 95 mol%.

Often this liquid phase P in terms of the contained amount of the acrylic acid contains from 0.20 to 30 or from 0.20 to 20, or from 0.20 to 10% of the mass. water (water from the hydrates (e.g., glyoxal hydrates) included in this amount of water). Often the specified water content in the liquid phase P in terms of the contained amount of acrylic acid is from 0.50 to 30% of the mass. or from 0.50 to 20 wt. -%, or from 0.50 to 10% of the mass.

At least one of the crystallization thermal methods of separation used is to obtain the liquid phase P, which should be processed according to the invention, from a gaseous mixture of products heterogeneously catalyzed partial vapor oxidation compounds, precursor of acrylic acid with 3 carbon atoms (a process in which at least partially can be returned to the mother liquor remaining in the subsequent corresponding to the crystallization invention the Department of glyoxal contained in the liquid phase P, (mother solution, which in this case is enriched in content of glyoxal)) is usually a rectification, azeotropic rectification, absorption, adsorption, extraction, desorption, dextrally, partial condensation, distillation, fractional condensation, or a combination of several of these methods. Often to obtain the liquid phase P, which should be treated according to the invention, the above methods are used multiple times.

In the simplest case, the liquid phase P, which should be treated according to the invention, can be absorbed and/or received only partial and/or fractional condensation of the condensate from the absorption and/or condensation separation of acrylic acid from a gaseous mixture of products heterogeneously catalyzed partial vapor-phase oxidation of at least one of the following in the publish connection-p is electonica, containing 3 carbon atoms. Then according to the invention preferably is returning the mother liquor enriched in content of glyoxal, in this process of absorption and/or condensation (if necessary fractional). With the appropriate approach in a mode of operation that should be applied, as described above, which includes a combination of at least one crystallization thermal separation processes to obtain the liquid phase P, which should be treated according to the invention, as well as crystallization of the Department of glyoxal according to the invention of the thus obtained liquid phase P, in which the mother liquor obtained by crystallization of the Department of glyoxal and enriched the content of this glyoxal, at least partially returned at least one of the crystallization thermal separation methods used to obtain the liquid phase P, which should be treated according to the invention there is an outlet opening of at least one substance flow enriched in content of glyoxal.

In the preferred embodiment, this outlet is located on the side of crystallization thermal separation processes. Typically, this is used the hole for the bottom liquid divide is part of the column, from which, for example, by lateral leads, shown itself liquid phase P, which should be treated according to the invention, or a flow of matter, which must be converted to further the process in the liquid phase P to be processed according to the invention (in the General case this outlet must be below the above-mentioned lateral leads). If the liquid phase P, which should be treated according to the invention is, for example, the condensate fraction, obtained as described in the publications of the patent application PCT/ER/050785, German application DE-A 102007055086 or EP-a 1 554 234, through the side discharge of the gaseous mixture of products heterogeneously catalyzed partial vapor oxidation connection predecessor with 3 atoms wereda, as mentioned above, the outlet for glyoxal may also be the outlet of the equipment for retro-splitting (vessel for dissociation) adducts Michael - oligomers of acrylic acid. This mainly draws attention to the fact that glyoxal at elevated temperatures (in the absence of specific catalysts splitting) in the first place turns into the aforementioned polyglycol or their hydrates.

As a rule, is the fact that if the liquid phase P, which should be processed according to the SNO invention, selected, for example, through the lateral discharge from the separation column, which is not thermal crystallization method of separation in the presence of the separation column of water absorbent supplied from the top down, and/or water reflux liquid, the content of glyoxal in the selected liquid phase is greater than the below is a sampling point in the separation column.

However, the outlet for glyoxal may be also or only on the side of the separation according to the invention, that is, on the side of crystallization. In this case, the selected fraction typically consists of a mother liquor enriched in content of glyoxal.

If the separation according to the invention is performed, for example, through a combination of dynamic and static crystallization in accordance with European patent application EP-A 616998, the sampling fraction glyoxal, enriched the content of this glyoxal, as a rule (with regard to technical feasibility), takes place in the sphere of static crystallization.

The latter, in particular, in case if when using the method according to the invention is not possible reverse flow of the mother liquor enriched in content of glyoxal, at least one of recrystallization thermal methods, R is selenia.

Last but not least, the method according to the invention is preferred when the liquid phase P, which should be treated according to the invention (for example, by one of the methods described above), is formed from a gaseous mixture of products heterogeneously catalyzed partial vapor oxidation compounds, precursor of acrylic acid, containing 3 carbon atoms, which contains at least 200 mol. ppm of glyoxal, or ≥ 250 mol. ppm of glyoxal, or ≥ 300 mol. ppm of glyoxal, or ≥ 400 mol. ppm of glyoxal, or ≥ 500 mol. ppm of glyoxal, or ≥ 750 mol. ppm of glyoxal, or ≥ 1000 mol. ppm of glyoxal, or ≥ 1250 mol. ppm of glyoxal, or ≥ 1500 mol. ppm of glyoxal, in terms of the molar amount of acrylic acid contained in this gaseous mixture of products.

In the normal case, the above-mentioned values of the glyoxal content in the gaseous mixture of products (restated accordingly) are ≤ 5 mol%. Often the content of acrylic acid in the above-mentioned gaseous mixture of products is from 1 to 30% vol.

The method according to the invention can be used also in the case when the liquid phase P, which should be treated according to the invention, is obtained by the fact that a gaseous mixture of products, if necessary, pre-cooled by direct and/or N. the direct heat exchange, subjected to the absorption of acrylic acid from this gaseous mixture of products with an aqueous solution or water (see, for example, European patent application EP-a 1 388 532, and EP-a 1 388 533). The resulting water absorbet containing acrylic acid, can directly represent the liquid phase P, which should be treated according to the invention.

However, if the content of acrylic acid in water absorbate should be even less than 70% of the mass.(in recalculation on weight of absorbate), but also for other reasons, this water absorbed (if necessary after preliminary desorption and/or Stripping of components absorbate, having a lower boiling point than acrylic acid) for separating at least a partial quantity contained in absorbate water can be subjected to azeotropic distillation (rectification), and then to produce crystallization separation according to the invention of the remaining (as the liquid phase P) the residual amount. As a suitable azeotropic agents should be called, for example, heptane, dimethylcyclohexane, ethylcyclohexane, toluene, ethylbenzene, octane, chlorobenzene, xylene or mixture (e.g., from 60% of the mass. toluene and 40% of the mass. heptane).

As an azeotropic agent may,one is to, also be used methyl isobutylketone or isopropylacetate.

Other suitable azeotropic agents offer in U.S. patent US 2004/0242826, European patent applications EP-A 778 255. EP-695 736, as well as in the prior art cited in these documents. Usually azeotropic distillation or rectification is preferably carried out at an operating pressure which is below atmospheric pressure.

Therefore, this proposal includes, in particular, the method according to the invention, in which acrylic acid and glyoxal in conjunction with other components having boiling points higher and lower than that of acrylic acid from a gaseous mixture of products heterogeneously catalyzed partial vapor oxidation is transferred to water in the liquid phase (for example, by absorption using an aqueous solution), and the resulting aqueous liquid phase using azeotropic distillation and/or distillation to remove at least part of the quantity of water, and remains liquid phase P, then according to the invention is treated by crystallization.

In principle, you can do as described in the publication of European patent applications EP-a 1 298 120, and EP-a 1 396 484, however, there is no longer a need to take special measures are required in these studies.

Here the need is IMO to emphasize, when the fractional condensation of the gaseous mixture of products from a technical point of view it is advisable (if necessary after pre-implemented direct and/or indirect (for example, using a fast cooling liquid according to the European patent applications EP-a 1 066 239 or EP-a 1 163201) the cooling of this gas mixture products), if this mixture is subjected to fractional condensation in the separation column with built-in elements for effective separation, separating itself, in a side selection of the crude acrylic acid (which optionally forms a liquid phase P to be processed according to the invention; optionally, this crude acrylic acid to obtain the liquid phase P is still processed by distillation and/or distillation) (see also European patent application EP-a 1 015 410, international application WO 2004/035514, German application DE-A 102 43 625, European application EP-a 1 015 411, German application DE-A 102 35 847, European application EP-a 1 159 249, EP-a 1 163 201, EP-a 1 066 239 EP-920 408). To minimize, if necessary, occurs when the fractional condensation loss of acrylic acid, this fractional condensation, if necessary, may additionally be combined with the absorption of water and/or aqueous solution.

The liquid phase thus obtained by the condensation (and PR is necessary rectification), it is advisable to undergo crystallization separation according to the invention in that case, if it has both the required content of acrylic acid, and related to this content of acrylic acid content of glyoxal.

The resultant mother liquor enriched in content of glyoxal, then, as mentioned in this publication, for example, in accordance with an example from European patent application EP-A 920 408 or international application WO 2004/035514, or European application EP-a 1 554 234, or application PCT/ER/050785 or, respectively, of German application DE-A 102007055086, at least partially, preferably completely, you can send back to the process of fractional condensation of acrylic acid from a gaseous mixture of products.

When this outlet for glyoxal have lower side leads to the crude acrylic acid.

Crystallization processing liquid phase P according to the invention, in particular, the liquid phase P, obtained by the above method by condensation and/or absorption and/or rectification, as a rule, is not subject to limitation, including a way of separating the mother liquor from kristalliset (can be used all the methods described in the prior art referred to in this publication). That is, it can is to be carried out in one stage or multistage, in continuous or batch mode. In particular, it can also be used as fractional crystallization. Usually when fractional crystallization of all stages, giving a crystalline acrylic acid, which (in particular, the content of glyoxal) is cleaner than the supplied processing liquid phase P, is called the stages of purification, and all other stages are called the stages of separation. It is advantageous if the multi-step processes are operated in countercurrent mode, in which crystallised at each stage is separated after crystallization from the mother liquor, and this crystallized is served on the appropriate stage with the next higher degree of purity, while remaining in the crystallized fraction is served at the appropriate stage near a lower degree of purity.

As a rule, the temperature of the liquid phase P in the process of carrying out the method according to the invention lies between -25°C and +14°C, especially between +12°C and -5°C.

For example, the method according to the invention can be made as a film crystallization (see vykladni description to German application DE-OS 2606364, European application EP-A 616998, EP-A 648520 and EP-A 776875). When the crystals raids!! in the form associated with each other, strongly cohesive layers. The separation of the precipitated crystals from the remaining residual melt (matoc the CSOs solution) is performed by simple removal of this residual melt. In principle distinguish between "static" and "dynamic" modes of film crystallization. Typical dynamic film crystallization of the liquid phase P is the forced convection of this liquid phase P. this can occur by pumping the liquid phase P full flow through the tube, by downloading this liquid phase P in the form of a flowing film (for example, in accordance with European patent application EP-A 616998) or by feeding inert gas into the liquid phase P, or by using ripple).

Static methods of liquid phase P is mixed (for example, in tubular or plate heat exchanger) and is deposited in the form of a layer using a slow lowering of the temperature in the heating circuit. After that, the residual melt (mother liquor) is drained, by slowly increasing the temperature of the layer of crystals is evaporated more heavily contaminated fraction, and then melted pure product (see international application WO 01/77056).

However, in accordance with the invention, the method according to this invention, in the case of all liquid phases P, described in this invention, is performed as a suspension crystallization in accordance with the technical solutions of international applications WO 01/77056, WO 02/055469, European applications EP-a 1 554 234, PCT/ER/050785, German patent application DE-A 102007055086, it is ccih applications 102007043759.7, 102007043758.9, 102007043748.1 and international application WO 03/078378.

In this case, as a rule, by cooling the liquid phase P will receive a suspension of crystals containing suspended in the form of crystalline acrylic acid, and the crystals of acrylic acid are lower, and the residual melt (mother liquor), a higher content of glyoxal (on conversion to the corresponding total number)than the liquid phase P to be treated. When crystals of acrylic acid, directly while in suspension, can be washed and/or deposited in a layer on the cooled wall, which they then suscribase and re suspendered in the residual melt (mother solution).

According to the invention take into account all suspension crystallizers and methods suspension crystallization described in international applications WO 01/77056, WO 02/055469, European patent applications EP-a 1 554 234, PCT/ER/050785, German patent applications DE-A 102007055086, German applications 102007043759.7, 102007043758.9, 102007043748.1, as well as international application WO 03/078378. Typically, the resulting suspension of crystals of acrylic acid has a solids content from 20 to 40% of the mass.

In addition, take into account everything mentioned in the above publications (primarily in the above-mentioned international application the patent WO-) separations are formed of suspended kristalliset and the remaining mother liquor (for example, mechanical methods of separation, such as centrifugation). According to the invention, this separation is preferably carried out in the wash column. Preferably it is about a wash column with forced movement precipitated crystals of acrylic acid. In this case, as a rule, the volume fraction of crystals in the crystalline layer reaches a value of > 0.5 in. Typically, this wash column is operated at values from 0.6 to 0.75. As the wash liquid is preferably applied to the melt, from a previously purified (separated) crystals of acrylic acid. This washing is usually carried out in a countercurrent. Thus, the method according to the invention comprises, in particular ways, which include the following stages:

a) crystallization of acrylic acid from the liquid phase P,

b) separating the crystals of acrylic acid from the remaining mother liquor (the residual liquid, the liquid residual phase),

c) at least partial melting of separated crystals of acrylic acid, and

d) at least a partial refund of the molten crystals of acrylic acid back to the step b) and/or stage (a).

At this stage b) is preferably carried out by washing in counterflow of molten pre-separated crystals acrylic is islote, fed back to the step (b).

First of all, when crystallization is carried out as a suspension crystallization, and moreover, when the subsequent separation of the mother liquor is carried out in a washing column, and moreover, if the wash liquid is applied to the melt of the crystals already pre-purified acrylic acid from the wash column is favorable that the liquid phase P often contains water.

That is, the method according to the invention not least includes processes in which the liquid phase P to be clear, under the action of cooling is transferred to the suspension of kristalliset, consisting of crystals of acrylic acid and liquid residual phase (residual liquid), and mass fraction of glyoxal in this crystallizatio acrylic acid less, and mass fraction of glyoxal in this residual liquid phase (mother solution) is greater than the mass fraction of glyoxal in the liquid phase P, if necessary, from this suspension kristalliset mechanically Teleut part of the remaining mother liquor and crystals of acrylic acid release from the remaining mother liquor in a wash column (see, for example, international application WO 01/77056, WO 03/041832, WO 03/041833 and WO 98/01414) provided that

a) the liquid phase P in terms therein acre the gross acid comprises from 0.20 to 30, often up to 20, often up to 10% massodi, and

b) as the wash liquid is applied to the melt kristalliset acrylic acid purified in the wash column.

In particular, the method according to the invention includes the above-mentioned methods, and the liquid phase P contains ≥ 80% of the mass. acrylic acid or ≥ 90% of the mass. acrylic acid, or ≥ 95% of the mass. acrylic acid.

In addition, according to the invention is preferred, if the water content in the liquid phase P in the case of the above described ways of conducting the process (or, respectively, in the most General case, when using the method according to the invention) in terms of the acrylic acid contained in this liquid phase P, is 0.2 or 0.4 to 8, or 10, or 20, or 30 wt. -%, or from 0.6 to 5 wt. -%, or from 0.6 to 3% of the mass.

Of course, the method according to the invention can also be used for all of the crude acrylic acid, which are mentioned in the publications listed in this document as the level of technology, as these acids satisfy the required content of acrylic acid and optionally the required content of glyoxal.

All the above is fair especially in the case when the wash column is a wash column with forced displacement is receiving crystals of acrylic acid, and this, first of all, if it is hydraulic or mechanical wash column, for example, in accordance with the international application WO 01/77056 and operated as described in this document.

All the above is a fair first of all, when this wash column is made and operated according to the technical solutions of international applications WO 03/041832 and WO 03/041833.

Thus, the method according to the invention using a sequence consisting of partial oxidation of at least one compound of the precursor containing 3 carbon atoms, to obtain a gaseous mixture of products having a high content of glyoxal, fractional condensation of acrylic acid from this gaseous mixture of products of partial oxidation, suspension crystallization of the obtained condensate of acrylic acid and separating the suspension kristalliset from the remaining mother liquor in a wash column using a melt of pure kristalliset as wash liquid, the most effective way, and also using only one stage of crystallization, the acquiring characterized by the absence of glyoxal acrylic acid, suitable for superabsorbant (of course, this acrylic acid may also be used dlesex applications discussed in international applications WO 02/055469 and WO 03/078378, and this is primarily the case when coming from inexpensive source of raw materials for the partial oxidation of compounds of the predecessor to 3 carbon atoms, contributing to the formation of glyoxal as a by-product).

Needless to say that all stages of the process described in this publication, are held in conditions of inhibition of polymerization. You can do as described in the prior art. A significant proportion of the total number available stabilizers process of obtaining acrylic acid take dibenzo-1,4-thiazin (phenothiazines - PTZ), 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-OH-TEMPO) and p-methoxyphenol (TFM), which can be represented in the liquid phase P, which should be treated according to the invention, or individually, or in pairs, or as a component of the ternary mixture. Usually the total amount of polymerization inhibitors contained in the liquid phase P is from 0.001 to 2 wt. -%, in terms of the total number contained in acrylic acid.

Due to the undesirable formation of oligomers of acrylic acid (Michael adducts) in the liquid phase P, which left to themselves, the method according to the invention after receiving this liquid phase P is applied to it as m is tenderly more quickly.

Preferred according to the invention, in the case of application of the method according to the invention together are separated, for example, contained in the liquid phase P by-products of the partial oxidation of compounds containing 4 carbon atoms (for example, butene-1, butadiene, n-butane, etc.), such as, for example, methacrylic acid, butyric acid, Butyraldehyde etc. In terms of contained molar amount of acrylic acid they may be present in the liquid phase P (in particular, all liquid phases P, are presented in this publication explicitly) in the same quantities as glyoxal. The same is true for acrolein, formaldehyde, acetaldehyde, propionic aldehyde, as well as all by-products of the partial oxidation of compounds 5 and 6 carbon atoms, and optionally contained in this liquid phase P of polyglycine and hydrates of polyglycolic. Therefore, this invention includes, in particular, the following options:

1. The method of separation of acrylic acid contained as a main product, and glyoxal contained as a by-product, in a mixture of products of partial heterogeneously catalyzed vapor-phase oxidation compounds, precursor of acrylic acid, containing 3 carbon atoms, in which receive the Jew is th phase P, which at least 70% of its mass consists of acrylic acid, and also, in terms of molar quantity contained in acrylic acid, contains at least 200 mol. ppm of glyoxal, characterized in that the Department of glyoxal from acrylic acid from the liquid phase P is carried out by crystallization, and acrylic acid accumulates in the formed product of crystallization, and glyoxal in the mother solution, the remaining crystallization.

2. The method according to the embodiment of the invention 1, characterized in that the liquid phase P, in terms of the contained molar amount of acrylic acid contains at least 300 mol. ppm glyoxal.

3. The method according to the embodiment of the invention 1, characterized in that the liquid phase P, in terms of the contained molar amount of acrylic acid contains at least 400 mol. ppm glyoxal.

4. The method according to the embodiment of the invention 1, characterized in that the liquid phase P, in terms of the contained molar amount of acrylic acid contains at least 500 mol. ppm glyoxal.

5. The method according to the embodiment of the invention 1, characterized in that the liquid phase P, in terms of the contained molar amount of acrylic acid contains at least 1000 mol. ppm is lixula.

6. The method according to the embodiment of the invention 1, characterized in that the liquid phase P, in terms of the contained molar amount of acrylic acid contains at least 1500 mol. ppm glyoxal.

7. Method according to one of embodiments of the invention 1-6, characterized in that the liquid phase P at least 75% of its mass consists of acrylic acid.

8. Method according to one of embodiments of the invention 1-6, characterized in that the liquid phase P at least 80% of its mass consists of acrylic acid.

9. Method according to one of embodiments of the invention 1-6, characterized in that the liquid phase P at least 85% of its mass consists of acrylic acid.

10. Method according to one of embodiments of the invention 1-6, characterized in that the liquid phase P at least 90% of its mass consists of acrylic acid.

11. Method according to one of embodiments of the invention 1-6, characterized in that the liquid phase P is at least 95% of its mass consists of acrylic acid.

12. Method according to one of embodiments of the invention 1-6, characterized in that the liquid phase P at least 96% of its mass consists of acrylic acid.

13. Method according to one of embodiments of the invention 1-6, Otley is audica fact, liquid phase P at least 97% of its mass consists of acrylic acid.

14. Method according to one of embodiments of the invention 1-13, characterized in that the compound is the precursor containing 3 carbon atoms, represents propylene.

15. Method according to one of embodiments of the invention 1-13, characterized in that the compound is the precursor containing 3 carbon atoms, represents acrolein.

16. Method according to one of embodiments of the invention 1-13, characterized in that the compound is the precursor containing 3 carbon atoms, represents propane.

17. Method according to one of embodiments of the invention 1-13, characterized in that the compound is the precursor containing 3 carbon atoms, represents glycerin.

18. Method according to one of embodiments of the invention 1-17, characterized in that the partial heterogeneously catalyzed vapor-phase oxidation of compounds of the predecessor to 3 carbon atoms is used, the source of the gaseous reaction mixture, which, in terms of the contained molar amount of coupling the predecessor to 3 carbon atoms, contains ≥ 200 mol. ppm, compounds with 2 carbon atoms.

19. Method according to one of embodiments of the invention 1-17, characterized those who, the partial heterogeneously catalyzed vapor-phase oxidation of compounds of the predecessor to 3 carbon atoms is used, the source of the gaseous reaction mixture, which, in terms of the contained molar amount of coupling the predecessor to 3 carbon atoms, contains ≥ 300 mol. ppm, compounds with 2 carbon atoms.

20. Method according to one of embodiments of the invention 1-17, characterized in that the partial heterogeneously catalyzed vapor-phase oxidation of compounds of the predecessor to 3 carbon atoms is used, the source of the gaseous reaction mixture, which, in terms of the contained molar amount of coupling the predecessor to 3 carbon atoms, contains ≥ 400 mol. ppm, compounds with 2 carbon atoms.

21. Method according to one of embodiments of the invention 1-17, characterized in that the partial heterogeneously catalyzed vapor-phase oxidation of compounds of the predecessor to 3 carbon atoms is used, the source of the gaseous reaction mixture, which, in terms of the contained molar amount of coupling the predecessor to 3 carbon atoms, contains ≥ 500 mol. ppm, compounds with 2 carbon atoms.

22. Method according to one of embodiments of the invention 1-17, characterized in that for casting the heterogeneously catalyzed vapor-phase oxidation of compounds of the predecessor to 3 carbon atoms is used, the source of the gaseous reaction mixture, which, in terms of the contained molar amount of coupling the predecessor to 3 carbon atoms, contains ≥ 750 mol. ppm, compounds with 2 carbon atoms.

23. Method according to one of embodiments of the invention 1-17, characterized in that the partial heterogeneously catalyzed vapor-phase oxidation of compounds of the predecessor to 3 carbon atoms is used, the source of the gaseous reaction mixture, which, in terms of the contained molar amount of coupling the predecessor to 3 carbon atoms, contains ≥ 1000 mol. ppm, compounds with 2 carbon atoms.

24. Method according to one of embodiments of the invention 1-17, characterized in that the partial heterogeneously catalyzed vapor-phase oxidation of compounds of the predecessor to 3 carbon atoms is used, the source of the gaseous reaction mixture, which, in terms of the contained molar amount of coupling the predecessor to 3 carbon atoms, contains ≥ 1500 mol. ppm, compounds with 2 carbon atoms.

25. Method according to one of embodiments of the invention 18 to 24, characterized in that the source of the gaseous reaction mixture contains from 4 to 20% vol. join the predecessor to 3 carbon atoms.

26. Method according to one of embodiments of the invention 18-25, about the tives such as those this original gaseous reaction mixture contains ≥ 1% of the mass. water vapour.

27. Method according to one of embodiments of the invention 18 to 25, characterized in that the source of the gaseous reaction mixture contains ≥ 2% of the mass. water vapour.

28. Method according to one of embodiments of the invention 18 to 25, characterized in that the source of the gaseous reaction mixture contains ≥ 3% of the mass. water vapour.

29. Method according to one of embodiments of the invention 18 to 25, characterized in that the source of the gaseous reaction mixture contains ≥ 5% of the mass. water vapour.

30. Method according to one of embodiments of the invention 18 to 25, characterized in that the source of the gaseous reaction mixture contains ≥ 7% of the mass. water vapour.

31. Method according to one of embodiments of the invention 1-30, wherein the liquid phase P was obtained from a gaseous mixture of products of partial heterogeneously catalyzed vapor-phase oxidation by use of at least one crystallization thermal separation processes.

32. The method according to the embodiment of the invention 31, wherein the at least one non-thermal crystallization method of separating includes at least one separation from the group, vkluchaya the absorption, partial condensation, fractional condensation, distillation, distillation and desorption.

33. The method according to variants of execution of the invention 31 or 32, characterized in that the enriched content of glyoxal, the mother liquor remaining in the crystallization, returns at least one of the crystallization thermal methods of separation.

34. The method according to the embodiment of the invention 33, wherein the rich content of glyoxal, the mother liquor remaining in the crystallization, is returned to the process of fractional condensation of the gaseous mixture of products heterogeneously catalyzed vapor-phase oxidation.

35. Method according to one of embodiments of the invention 1-34, wherein the crystallization separation is performed using a suspension crystallization.

36. The method according to the embodiment of the invention 35, characterized in that formed during this suspension crystallization suspension crystallized and the remaining mother liquor are separated from each other in the wash column.

37. The method according to the embodiment of the invention 36, characterized in that the washing column this suspension crystallized washed melt crystals of acrylic acid, separated in the wash column previously.

38. The method according to the SNO one of the variants of the invention 1-37, characterized in that it comprises the following process stages:

A. crystallization of acrylic acid from the liquid phase P;

b. the separation of crystals of acrylic acid from remaining in the crystallization mother liquor;

C. at least partial melting separated in stage (b) crystals of acrylic acid;

d. at least a partial refund of molten crystals of acrylic acid from stage C) at stage b) and/or stage (a).

39. Method according to one of embodiments of the invention 1-38, wherein the liquid phase P, in terms of the contained acrylic acid contains from 0.2 to 30 wt%. water.

40. Method according to one of embodiments of the invention 1-39, and glyoxal contained in a gaseous mixture of products is transferred to water in the liquid phase, the aqueous liquid phase using azeotropic distillation to remove at least a partial amount of water, and remains liquid phase P.

41. Method according to one of embodiments of the invention 1-40, characterized in that the liquid phase P contains glyoxal at least 50 mol%. in the form of Monomeric glyoxal monohydrate and/or Monomeric glyoxal dihydrate.

42. Method according to one of embodiments of the invention 1-40, characterized in that the liquid phase P contains glyoxal p is at least 70 mol%. in the form of Monomeric glyoxal monohydrate and/or Monomeric glyoxal dihydrate.

43. Method according to one of embodiments of the invention 1-40, characterized in that the liquid phase P contains glyoxal at least 90 mol%. in the form of Monomeric glyoxal monohydrate and/or Monomeric glyoxal dihydrate.

44. Method according to one of embodiments of the invention 1-43, wherein the gaseous mixture of products, in terms of the contained molar amount of acrylic acid, contains at least 200 mol. ppm glyoxal.

45. Method according to one of embodiments of the invention 1-43, wherein the gaseous mixture of products, in terms of the contained molar amount of acrylic acid contains at least 400 mol. ppm glyoxal.

46. Method according to one of embodiments of the invention 1-43, wherein the gaseous mixture of products, in terms of the contained molar amount of acrylic acid contains at least 750 mol. ppm glyoxal.

47. Method according to one of embodiments of the invention 1-46, wherein within the liquid phase P is contained in a gaseous mixture of products of acrylic acid is translated in condensed matter (e.g. liquid) phase, and the remaining when this is m gaseous residual gas at least partially returned to the stage partial heterogeneously catalyzed vapor-phase oxidation of compounds of the predecessor to 3 carbon atoms.

48. Method according to one of embodiments of the invention 1-47, characterized in that it includes the way in which crystallized acrylic acid is melted and injected into a radical polymerization to obtain at least one polymer.

Examples:

I. confirmation of the effect of Monomeric glyoxal in acrylic acid, is extremely conducive to unwanted free-radical polymerization of acrylic acid

1. Obtaining a solution of Monomeric glyoxal in anhydrous methanol

Finely chopped dihydrate glyoxal trimer in the amount of 2.0 g (Fluka, purity > 95%) and 5.0 g of finely ground P2O5(company Aldrich, purity > 98%) was mixed to homogeneity. Then this mixture at a pressure of < 50 mbar was heated to 180°C and continuously released during this gaseous stream consisting of Monomeric glyoxal and, if necessary, slight traces of water vapor was passed in anhydrous methanol (Aldrich, purity > 99.8 per cent) through finely ground P2O5(for binding residual traces of water vapor).

In terms of the initial amount of methanol in the methanol was introduced and dissolved therein 0.3% of the mass. Monomeric glyoxal (see also Y. Chen, Zhu L in "Wavelength-Dependent Photolysis of Glyoxal in the 290-420 nm Region", J. Phys. Chem. A, 2003, 107, 4643-4651). The resulting methanol solution then is bonachela as the solution of M (in this methanol solution of glyoxal and methanol are formed corresponding labile acetals,

that with little temperature increase back again split into Monomeric glyoxal and methanol).

2. Obtaining pure acrylic acid mixed with minor amounts of various possible aldehydes as products

Previously prepared 5 identical samples (each 0.5 ml) of pure acrylic acid. Pure acrylic acid, for stable storage stable simple monometallism ether of hydroquinone (TFM), just before it was moved under reduced pressure and stabilized by addition of 10 mass. ppm fenotiazina (PTZ).

The purity of the thus obtained samples of pure acrylic acid was > 99.8% of the mass. when the total content of aldehydes and ketones < 10 mass. ppm Storage of these samples was carried out in a frozen condition.

Then, in these samples, as described below, contributed impurities by davisiana corresponding aldehydes (in the case of glyoxal was used for this solution M; mol. ppm are always contained the molar amount of acrylic acid; because of the content of methanol in the solution M for introducing impurities of aldehydes, different from glyoxal, it was necessary to introduce an appropriate amount of methanol):

The image is C 1: 86 mol. ppm Monomeric glyoxal
Sample 2:96 mol. ppm benzaldehyde
Sample 3:166 mol. ppm formaldehyde
Sample 4:104 mol. ppm 2-shrilled
Sample 5:113 mol. ppm of acetaldehyde

In air they were soldered in the same glass ampoules with the maximum amount of respectively 1.8 ml, these capsules immediately after their final preparation was kept in rotation at a temperature of 120°C in a drying Cabinet with air circulation to provide mixing in full. After that visually, we registered the time T to complete polymerization of the corresponding samples.

This series of experiments was repeated three times and the obtained values calculated arithmetic mean. The average results of time T for the respective samples was:

Sample 1:117 min
Sample 2:222 min
Sample 3:197 min
Sample 4:199 min
Sample 5:174 min

These results confirm the unique position of Monomeric glyoxal.

II. Crystallization separation according to the invention

1. Through acrylic acid, not containing glyoxal, having the following content of impurities (these figures are for the gas chromatographic analysis; determination of water was carried out by titration according to Karl Fischer; determination fenotiazina - wet analysis)

tr>
37mass. ppm of allylacetate,
3319mass. ppm benzaldehyde,
3404mass. ppm diacrylates acid,
1,94%mass. acetic acid,
0,91%mass. propionic acid,
4211mass. ppm 2-furaldehyde (furan-2-aldehyde),
33mass. ppm 3-furaldehyde (furan-3-aldehyde),
348mass. ppm water, and
297mass. ppm fenotiazina,

as well as the content of acrylic acid 95,80% wt., missed gaseous stream Monomeric glyoxal obtained as described in paragraph 1.1., while this acid, in terms of the contained amount of acrylic acid was not contaminated by the impurity of Monomeric glyoxal in the number 1741 mol. ppm (=1277 Massud in terms of the total weight of acrylic acid with impurities).

She then with a flow rate of 135 kg/h and at a temperature of 17.3°C was applied in the disk mold with cooling (with a capacity of fluid approximately 95 liters) with a cooled drives scraping the crystals. This mold had 7 round, located in the tank at the same distance from each other, constituting 12 cm, cooled drives. The diameter of these cooled drive was 32 cm and the thickness of the disk was 15 mm with the wall thickness of 2.5 mm Cooled surfaces were made of stainless steel (material grade according to DIN 1.4571). Through these disks as a cooling agent missed (353 l/h) a mixture of water and glycol (55% vol. water, 45% vol. glycol). The cooler was leaking, having an inlet temperature in the first cooling disk 2.5°C, and leave the last cooled drive exit temperature of 8.6°C. Smoot the OIC acid, containing impurities, and the cooling agent is passed through the mold in the countercurrent mode. At the same time the edges of the cooled drives, which were not suscribanse sludge was heated with a bending around their hollow profile (hollow tube with an external diameter of 12 mm), to prevent formation of a crust of crystals. For this purpose, through these hollow profiles on the cooled drives, parallel missed with a total flow rate of 51 l/h water-glycol mixture, which, however, the inlet temperature of 24°C. Suscribase knives cooled disk was set in motion by means of a horizontal shaft with a speed of 26 rpm Suspension of kristalliset obtained in the mould, leaving him with a temperature of 10.6°C.

Suspension of kristalliset acrylic acid at a flow rate of 119 kg/h was extracted from the mold through the coarse sieve (mesh size of approximately 3 mm; it is a coarse sieve was for the purpose of delay generated in the mould of larger agglomerates of crystals, because they could cause clogging of the piping for feeding the suspension into the wash column) with a temperature of 10.6°C and pumped into the hydraulic wash column at the top. The convoy consisted of having the form of a circular cylinder double glass shirt (height: 1000 mm; the outer diameter of the inner cylinder bore: 100 mm, thickness is and the inner wall of the cylinder: 9 mm; the outer cylinder was tightly sealed around the inner cylinder by means of suitable gaskets; the space between them was filled with air; the outer diameter of the outer cylinder: 130 mm; the wall thickness of the outer cylinder: 5 mm). In the inner cylinder in the center was inserted metal filter tube (made of stainless steel (material grade according to DIN 1.4571), which had an external diameter of 20 mm and a wall thickness of 1.6 mm filter pipe was embedded cylindrical envelope of the filter with the lower edge at 200 mm above the lower edge of the glass shirts, height 40 mm, with an external diameter of 20 mm, through which played a liquid phase containing in suspension kristalliset acrylic acid. Thanks abstraction above the liquid phase in a glass cylinder around the filter tube was a layer of kristalliset, for which its value (the height of the layer) supported on the level of 510 mm using optical measurement height (measured from the bottom edge of the glass shirts). To adjust the height of the layer controlling the flow of the liquid phase withdrawn through the filter pipe, approximately 95 kg/h, in the upper part of the wash column, moved it back. On the lower end of the glass cylinder the washed layer kristalliset was removed using a rotary circular knife (about 30 who/min), and remote crystallized was pumped and melted in the melting cycle, including the pump, heater, a device for adding inhibitor and associated pipelines. Addition of an inhibitor was carried out in the form dissolved in the pure melt fenotiazina (PTZ) so that the content in this series PTZ melting point is approximately 200 mass. ppm Temperature in the cycle of melting before returning pure melt required for washing the crystals at the lower end of the wash column, was 18°C.

Only about 5.5 kg/h of molten kristalliset selected from the cycle of melting as the pure product (pure melt). Thus the value of the stream of net product selected from the cycle of melting, was adjusted so that the layer kristalliset, visible from the outside, at an altitude of about 90 to 110 mm above the lower edge of the glass cylinder, formed the wash front. For regulating the flow of pure melt is selected in the cycle of melting layer kristalliset at a height of 100 mm above the lower edge of the glass cylinder was used, the temperature control valve in the pipeline for the selection of a pure melt (adjustment selected flow was set at a value of 11.5°C.

Analysis of the liquid phase (mother liquor)is withdrawn from the filter is ment pipe, gave the content of glyoxal 1365 masses. ppm (calculated on the weight of the mother liquor).

Analysis of molten kristalliset selected from the cycle of melting, showed the content of glyoxal less than 0.1 mass. ppm (in terms of mass of kristalliset).

Thus, both the above values are calculated enrichment factor AndGlyconstituting a > 13650.

2. Was repeated experiment 11.1, however, the introduction of impurities glyoxal produced by purchased from the firm Aldrich and stored at 25°C. the aqueous solution, which according to their own analysis contained glyoxal 40% of its mass (calculated on the Monomeric glyoxal). The introduction of impurities in the acrylic acid was accompanied by a slight sediment, which probably can explain the high-molecular compound poorly soluble in the acrylic acid polyglycolide (or their hydrates). Therefore, it was filtered and obtained as a filtrate acrylic acid containing an admixture of 1877 mol. ppm glyoxal. It was treated as in experiment 11.1. The experimentally determined thus enrichment factor AndGly(calculated on the Monomeric glyoxal) was > 14720.

Provisional application for U.S. patent no. 61/084109, filed July 28, 2008, and No. 61/091900, filed August 26, 2008, included in this C the turnout through literary references. Taking into account the above technical solution, there are numerous changes and deviations given invention. Therefore, we can assume that this invention, in the framework of the appended claims, may be implemented differently than described therein.

1. The method of separation of acrylic acid contained as a main product, and glyoxal contained as a by-product, in a mixture of products of partial heterogeneously catalyzed vapor-phase oxidation compounds, precursor of acrylic acid, containing 3 carbon atoms, which are the liquid phase P, which is at least 70% of its mass consists of acrylic acid, and also, in terms of molar quantity contained in acrylic acid, contains at least 200 mol. ppm of glyoxal, characterized in that the Department of glyoxal from acrylic acid from the liquid phase P is carried out by crystallization, and acrylic acid accumulates in the formed product of crystallization, and glyoxal in the mother solution, the remaining crystallization.

2. The method according to claim 1, characterized in that the liquid phase P, in terms of the contained molar amount of acrylic acid contains at least 300 mol. ppm glyoxal.

3. The method according to claim 1, characterized in that the liquid phase of the RPO at least 75% of its mass consists of acrylic acid.

4. The method according to claim 1, characterized in that
connection-precursor, containing 3 carbon atoms, represents propylene.

5. The method according to claim 1, characterized in that
connection-precursor, containing 3 carbon atoms, represents acrolein.

6. The method according to claim 1, characterized in that
connection-precursor, containing 3 carbon atoms, represents propane.

7. The method according to claim 1, characterized in that
connection-precursor, containing 3 carbon atoms, represents glycerin.

8. The method according to claim 1, characterized in that the partial heterogeneously catalyzed vapor-phase oxidation
join the predecessor to 3 carbon atoms use the original gaseous reaction mixture, which, in terms of the contained molar amount of coupling the predecessor to 3 carbon atoms, contains ≥ 200 mol. ppm, compounds with 2 carbon atoms.

9. The method according to claim 1, characterized in that the partial heterogeneously catalyzed vapor-phase oxidation
join the predecessor to 3 carbon atoms use the original gaseous reaction mixture, which, in terms of the contained molar amount of coupling the predecessor to 3 carbon atoms, contains ≥ 300 mol. ppm, compounds with 2 carbon atoms.

10. The method according to claim 8, characterized those who, the source of the gaseous reaction mixture contains from 4 to about 20. %.
join the predecessor to 3 carbon atoms.

11. The method according to claim 8, characterized in that the source of the gaseous reaction mixture contains ≥ 1 wt. % of water vapor.

12. The method according to claim 8, characterized in that the source of the gaseous reaction mixture contains ≥ 2 wt. % of water vapor.

13. The method according to claim 1, characterized in that the liquid phase P was obtained from a gaseous mixture of products of partial heterogeneously catalyzed vapor-phase oxidation by use of at least one crystallization thermal separation processes.

14. The method according to item 13, wherein the at least one non-thermal crystallization method of separating includes at least one separation from the group, including absorption, partial condensation, fractional condensation, distillation, distillation and desorption.

15. The method according to item 13, wherein the rich content of glyoxal, the mother liquor remaining in the crystallization, return at least one of the crystallization thermal methods of separation.

16. The method according to item 15, wherein the rich content of glyoxal, the mother liquor remaining in the crystallization, return to the process of fractional condensation of the gaseous mixture of products heterogeneously catalyzed vapor-phase oxidation.

17. The method according to claim 1, characterized in that the crystallization separation is produced using a suspension crystallization.

18. The method according to 17, characterized in that formed during this suspension crystallization suspension crystallized and the remaining mother liquor separated from each other in the wash column.

19. The method according to p, characterized in that the washing column this suspension crystallized washed melt crystals of acrylic acid, separated in the wash column previously.

20. The method according to claim 1, characterized in that it comprises the following stages of the process:
a) crystallization of acrylic acid from the liquid phase P;
b) separating the crystals of acrylic acid from remaining in the crystallization mother liquor;
c) at least partial melting separated in stage (b) crystals of acrylic acid;
d) at least a partial refund of molten crystals of acrylic acid from stage c) at stage b) and/or on a stage).

21. The method according to claim 1, characterized in that the liquid phase P, in terms of the contained acrylic acid contains from 0.2 to 30 wt. % water.

22. The method according to claim 1, characterized in that to obtain the liquid phase P of acrylic acid and glyoxal contained in a gaseous mixture of products is transferred to water in the liquid phase, the aqueous liquid phase using azeotropic distillation to remove at least a partial amount of water, and remains liquid phase P.

23. The method according to claim 1, characterized in that the liquid phase P contains glyoxal at least 50 mol. % in the form of Monomeric glyoxal monohydrate and/or Monomeric glyoxal dihydrate.

24. The method according to claim 1, characterized in that the gaseous mixture of products, in terms of the contained molar amount of acrylic acid, contains at least 200 mol. ppm glyoxal.

25. The method according to claim 1, characterized in that within the liquid phase P is contained in a gaseous mixture of products of acrylic acid transfer in the condensed phase, and while it remains gaseous residual gas at least partially return to the stage partial heterogeneously catalyzed vapor-phase oxidation of compounds of the predecessor to 3 carbon atoms.



 

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32 cl, 3 tbl, 4 dwg, 6 ex

FIELD: chemistry.

SUBSTANCE: described is a method of making catalytically active geometric moulded articles K, which contain as active mass, a multi-element oxide I with general stoichiometric formula (I): [BinZ1bOx]p[BicMo12FedZ2eZ3fZ4gZ5hZ6iOy]1 (I), according to which Z1 denotes tungsten or tungsten and molybdenum, under the condition that the amount of tungsten is at least 10 mol % of the total molar amount Z1, Z2 denotes an element or multiple elements selected from a group which includes nickel and cobalt, Z3 denotes an element or multiple elements selected from a group which includes alkali metals, alkali-earth metals and gallium, Z4 denotes an element or multiple elements selected from a group which includes zinc, phosphorus, arsenic, boron, antimony, tin, cerium, vanadium and chromium, Z5 denotes an element or multiple elements selected from a group which includes silicon, aluminium, titanium, tungsten and zirconium, Z6 denotes an element or multiple elements selected from a group which includes copper, silver, gold, yttrium, lanthanum and lanthanides, a is a number from 0.1 to 3, b is a number from 0.1 to 10, d is a number from 0.01 to 5, e is a number from 1 to 10, f is a number from 0.01 to 2, g is a number from 0 to 5, h is a number from 0 to 10, i is a number from 0 to 1, p is a number from 0.05 to 6, and x, y are respectively numbers defined by valence and number of atoms other than oxygen atoms in formula (1), wherein a fine mixed oxide BiaZ'bOx is formed in form of a starting mass A1, the particle diameter d50A1 of which satisfies the condition 1mcmd50A1100mcm, using sources, other than oxygen, of elements of the component part T of the multi-element oxide I, represented by [BicMo12FedZ2cZ3fZ4gZ5hZ6iOy]i, a homogeneous aqueous mixture M is formed in an aqueous medium, wherein: each of the sources used when forming the aqueous mixture M passes through a dispersion degree Q, characterised by that the particle diameter corresponds to d90Q5mcm, and the aqueous mixture M contains bismuth, molybdenum, iron, Z2, Z3, Z4, Z3 and Z6 in the stoichiometric formula (I*): BicMo12FedZ2cZ3fZ4gZ5hZ6i (I*); from the aqueous mixture M, by drying and controlling the dispersion degree d90A2, a fine starting mass A2 is formed, the particle diameter d90A2 of which satisfies the condition400mcmd90A210mcm; the starting mass A1 is mixed with starting mass A2 or the starting mass A1, starting mass A2 and a fine auxiliary moulding agent are mixed to obtain a fine starting mass A3, which contains elements of the multi-element oxide I other than oxygen that are introduced therein through starting mass A1 and A2, in stoichiometric formula (1**): [BiaZ'b]p[BicMo12FedZ2eZ3fZ4gZ5hZ6i]l (I**);geometric moulded articles V are formed from the fine starting mass A3; the moulded articles V undergo heat treatment at high temperature to obtain catalytically active geometric moulded articles K, wherein the stoichiometric coefficient "c" lies in the range 0<c≤0.8.

EFFECT: described is a method for heterogeneously catalysed partial gas-phase oxidation of an alkane, alkanol, alkanal, alkene and/or alkenal containing 3-6 carbon atoms in a catalyst bed, wherein the catalyst bed contains catalytically active moulded articles which can be made using said method.

15 cl, 3 tbl, 13 ex

FIELD: chemistry.

SUBSTANCE: invention relates to methods of producing catalytic moulded articles and use thereof. Described is a method of making catalytically active geometric moulded articles K, which contain as active mass, a multi-element oxide I with general stoichiometric formula (I): [BilWbOx]a[Mo12Z1cZ2dFeeZ3fZ4gZ5hOy]l (I), in which Z1 denotes an element or multiple elements selected from a group which includes nickel and cobalt, Z2 denotes an element or multiple elements selected from a group which includes alkali metals, alkali-earth metals and thallium, Z3 denotes an element or multiple elements selected from a group which includes zinc, phosphorus, arsenic, boron, antimony, tin, cerium, vanadium, chromium and bismuth, Z denotes an element or multiple elements selected from a group which includes silicon, aluminium, titanium, tungsten and zirconium, Z5 denotes an element or multiple elements selected from a group which includes copper, silver, gold, yttrium, lanthanum and lanthanides, a is a number from 0.1 to 3, b is a number from 0.1 to 10, c is a number from 1 to 10, d is a number from 0.01 to 2, e is a number from 0.01 to 5, f is a number from 0 to 5, g is a number from 0 to 10, h is a number from 0 to 1, and x, y are respectively defined by valence and number of atoms other than oxygen in formula (I), wherein a fine mixed oxide BilWbOx is formed in form of a starting mass A1, the particle diameter d50A1 of which satisfies the condition 1 mcm ≤ d50A1 ≤10 mcm; a homogeneous aqueous mixture M is formed in an aqueous medium using sources, other than oxygen, of elements of the component part T=[Mo12ZlcZ2dFeeZ3fZ4gZ5hOy]l of the multi-element oxide I, wherein: each of the sources used when forming the aqueous mixture M passes through a dispersion degree Q, which corresponds to particle diameter d90Q ≤ 5 mcm, and the aqueous mixture M contains molybdenum, Z1, Z2, iron, Z3, Z4 and Z5 in the stoichiometric formula (I*): Mo12ZlcZ2dFecZ3fZ49Z5h (I*); from the aqueous mixture M, by drying and controlling the dispersion degree, a fine starting mass A2 is formed, the particle diameter d90A2 of which satisfies the condition 200 mcm ≥ d90A2 ≥ 20 mcm; the starting mass A1 is mixed with starting mass A2 or the starting mass A1, starting mass A2 and a fine auxiliary moulding agent are mixed to obtain a fine starting mass A3, which contains elements of the multi-element oxide I other than oxygen that are introduced therein through starting mass A1 and A2, in stoichiometric formula (1**): [BilWb]a[Mo12ZlcZ2dFeeZ3fZ4gZ5h]i (I**); geometric moulded articles V are formed from the fine starting mass A3, and the moulded articles V undergo heat treatment at high temperature to obtain catalytically active geometric moulded articles K, wherein the product F:(d50A1)0,7(d90A2)1,5(a1) is ≥820.

EFFECT: described is a method for heterogeneously catalysed partial gas-phase oxidation of an alkane, alkanol, alkanal, alkene and/or alkenal containing 3-6 carbon atoms in a catalyst bed, wherein the catalyst bed contains catalytically active moulded articles made using said method.

15 cl, 8 dwg, 10 tbl, 2 ex

FIELD: process engineering.

SUBSTANCE: invention relates to plate-reactor, method of its fabrication and method of producing reaction product. Reactor comprises reaction chamber for interaction of initial gases, multiple heat-exchange plates arranged side by side in reaction chamber and device to feed heat racier in said heat-exchange plates. Every said heat-exchange plates comprises multiple heat-exchange tubes interconnected along periphery or edges of cross-section outline. Note here that design distance between surfaces of said plates as-measured in direction perpendicular to the plate. Surfaces consisting of axes of said plates are equidistant relative to aforesaid plane to make 5-50 mm while departure of actual distance between surface from design magnitude makes -0.6 to plus 2.0 mm.

EFFECT: ruled out abrupt increase in reaction rate, easy distribution of catalyst, decreased pressure losses, eliminated catalyst damages, high efficiency.

31 cl, 43 dwg, 6 tbl, 13 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of using gas-phase partial oxidation on a heterogeneous catalyst of acrolein into acrylic acid and methacrolein into methacrylic acid on a fixed catalyst bed lying in a shell-and-tube reactor in reaction tubes of a vertical bundle of reaction tubes enclosed in the reactor shell, when both ends of each of the reaction tubes are open and each reaction tube, through its top end, tightly enters a through-hole which is tightly built into the top part of the reactor shell of an upper tube sheet, and through its bottom end, tightly enters a through hole which is tightly built into the bottom part of the reactor shell of a lower tube sheet, wherein the outer surface of the reaction tubes, the upper and lower tube sheets, as well as the reactor shell together bound the space which surrounds the reaction tubes, wherein each of the two tube sheets is closed by a reactor cover having at least one hole, when in order to put into operation, a starting gaseous reaction mixture containing ≥3 vol. % acrolein or methacrolein and also molecular oxygen is fed into the reaction tubes of the shell-and-tube reactor through at least one hole, denoted hereafter as E, in one of the two reactor covers, and the gaseous product mixture containing acrylic acid or methacrylic acid, which is formed as a result of gas-phase partial oxidation of acrolein or methacrolein into acrylic acid or methacrylic acid by passing through a fixed catalyst bed lying in the reaction tubes, is removed through at least one hole in the other reactor cover, wherein at least one liquid heat carrier is fed from the side of the shell to the reaction tubes of the shell-and-tube reactor, the movement of the liquid heat carrier being such that each of the surfaces of both tube shells facing each other is covered by the liquid heat carrier, and wherein at least one liquid heat carrier enters the space surrounding the reaction tubes with temperature Twin and comes out of said space with temperature Twout. At the moment of use, the starting gaseous reaction mixture containing ≥3 vol. % acrolein or methacrolein is fed through at least one hole in the reactor cover, wherein temperature Twin of at least one liquid carrier which is in contact with the tube sheet closed by the reactor cover having at least one hole E, denoted hereinafter as reactor sheet E, is not lower than 290°C; the starting gaseous reaction mixture coming through at least one hole E has temperature ≤285°C and temperature of the surface of the reactor sheet E facing the reactor cover having at least one hole E, denoted hereinafter as the surface of reactor sheet E, is ≤285°C.

EFFECT: improved method.

16 cl, 4 dwg, 6 tbl, 3 ex

FIELD: process engineering.

SUBSTANCE: invention relates to production of catalyst for producing unsaturated aldehyde and unsaturated carboxyl acid. Proposed method comprises applying catalyst powder coating on inert substrate to produce applied catalyst wherein inert substrate features ring shape and has outer periphery bent in longitudinal direction of substrate. Note here that catalyst is produced in atmosphere of granulating chamber at application of coating to ensure absolute humidity of 0.01 and higher. Catalyst thus produced is used for gas-phase oxidation of propylene, isobutylene, tert-butyl alcohol or methyl-tert-butyl ether to produce appropriate unsaturated aldehyde, or for gas-phase oxidation of said aldehyde to produce carboxylic acid.

EFFECT: higher activity and friction stability at high yield of target product.

4 cl, 9 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method for heterogeneously catalysed partial gas-phase oxidation of propylene to acrylic acid, according to which in the first reaction zone an initial gaseous reaction mixture 1, containing propylene and molecular oxygen as reactants and at least propane as an inert diluent gas, with molar ratio O2: C3H6 ≥ 1, at a first reaction step at high temperature, is passed through at least one first catalyst layer whose active mass contains at least one polymetallic oxide based on molybdenum, iron and bismuth, wherein conversion of propylene during single passage through the first catalyst layer is ≥90 mol %, while total selectivity (SAC) of formation acrolein and acrylic aicd as a by-product is ≥80 mol %; if necessary, temperature of the gaseous mixture of reaction products obtained at the first reaction step is lowered by direct cooling, indirect cooling or direct and indirect cooling; if necessary, a secondary gas is added to said mixture in form of molecular oxygen or inert gas or molecular oxygen and inert gas, and in form of an initial gaseous reaction mixture 2, containing acrolein and molecular oxygen as reactants and at least propane as an inert diluent gas, with molar ratio molecular oxygen O2: C3H4O≥0.5, at a second reaction step at high temperature and with formation of a gaseous mixture of reaction products 2, is passed through at least one second catalyst layer whose active mass contains at least one polymetallic oxide based on molybdenum and vanadium, wherein conversion of acrolein during single passage through the second catalyst layer is ≥95 mol %, and where total selectivity (SAA) of formation of acrylic acid at both reaction steps in terms of converted propylene is ≥70 mol %, and where the initial gaseous reaction mixture 1 contains ≤3 mol % cyclopropane in terms of the molar amount of propane contained therein, and which was obtained using crude propylene consisting of at least 90 wt % propylene from at least 97 wt % propane and propylene.

EFFECT: product obtained using the disclosed method has very low content of propionic acid.

28 cl, 2 ex

FIELD: chemistry.

SUBSTANCE: in a first reaction zone, a starting reaction gas mixture 1 which contains propylene, molecular oxygen and at least one inert diluent gas molar ratio O2:C3H6≥1, at a first reaction stage at high temperature is passed through at least one first catalyst bed whose active mass contains at least one polymetal oxide based on molybdenum, iron and bismuth, wherein conversion of propylene in a single passage through the first catalyst bed is ≥90 mol %, while the total selectivity (SAC) of formation of acrolein and acrylic acid by-product is ≥80 mol %; optionally the temperature of the product gas mixture 1 obtained at the first reaction stage is reduced by direct cooling or indirect cooling or direct and indirect cooling; optionally secondary gas in the form of molecular oxygen or inert gas or molecular oxygen and inert gas is added to product gas mixture 1, and as a starting reaction gas mixture 2 which contains acrolein, molecular oxygen and at least one inert diluent gas in molar ratio O2:C3H4O≥0.5 at a second reaction stage at high temperature is passed through at least one second catalyst bed whose active mass contains at least one polymetal oxide based on molybdenum and vanadium, wherein acrolein conversion in a single passage through the second catalyst bed is ≥90% mol %. Total selectivity (SAA) of formation of acrylic acid on both reaction stages with respect to converted propylene is ≥70 mol %, after which acrylic acid contained in the product gas mixture 2 obtained at the second reaction stage in a separation zone is converted to condensed from which it is separated in a second separation zone by at least one thermal separation technique, characterised by that the starting reaction gas mixture 1 contains from 100 mol ppm to 3 mol % cyclopropane based on the molar amount of propylene contained therein, and propylene, required as the starting substance for this method, is added to the starting reaction gas mixture 1 in form of crude propylene which, based on volume thereof, contains at least 90 vol. % propylene, wherein at least one thermal separation technique in the second separation zone includes at least one technique for crystallisation separation of acrylic acid from the condensation phase.

EFFECT: method enables to obtain the end product depleted of propionic acid.

16 cl, 1 ex

FIELD: blasting.

SUBSTANCE: in the first reaction zone A at least two gaseous supply flows are supplied, containing propane, at least one of which contains fresh propane, to produce a reaction gas A; - in the reaction zone A the reaction gas A passes through at least one layer of catalyst, in which, by means of partial heterogeneous-catalysed dehydration of propane, molecular hydrogen and propylene are produced; - molecular oxygen is supplied into the reaction zone A, which oxidises in the reaction zone A at least a part of molecular hydrogen contained in the reaction gas A to water vapour - the gas-product A is taken from the reaction zone A, containing propylene, propane, molecular hydrogen and water vapour; B) water vapour contained in the gas-product A, if necessary, fully or partially by means of direct and/or indirect cooling, is separated in the first zone of separation I by the method of condensation with preservation of the gas-product A*; C) in the reaction zone B, by supply of molecular oxygen, the gas-product A or the gas-product A* is used to supply at least into one oxidisation reactor with the reaction gas B, comprising propane, propylene and molecular hydrogen, and propylene contained in it is exposed to heterogeneous-catalysed partial oxidation in the gas phase to produce acrolein or acrylic acid or their mixture as a target product, and also the gas-product B containing non-converted propane; D) from the reaction zone B the gas-product B is released, and the target product contained in it is separated in the second separation zone II, besides, the residual gas containing propane remains; E) whenever necessary, a part of the residual gas is returned having the composition of the residual gas, as a supply flow containing propane, into the reaction zone A; F) in the zone of separation III propane contained in the residual gas that has not been returned into the reaction zone A, from which earlier, if required, water vapour contained in it has been removed, possibly, by condensation and/or using a separating membrane, molecular hydrogen contained in it has been fully or partially removed, is separated by means of absorption in an organic dissolvent (absorbent) with production of absorbate containing propane; and G) in the separation zone IV propane is separated from absorbate and returned into the reaction zone A in the form of a supply flow containing propane, besides, in the reaction zone A enough amount of molecular hydrogen is oxidised to water vapour so that this hydrogen amount oxidised in the reaction zone A to the water vapour makes from 30 to 70 mol% of molecular hydrogen amount produced in the reaction zone A, and for values of the working pressure P in each case identified at the inlet to an appropriate area, in different zones of the method under the invention the following ratios are in effect: Preaction zone A>Pseparation zone I>Preaction zone B>Pseparation zone II>Pseparation zone III>Pseparation zone IV>Preaction zone A.

EFFECT: higher yield.

27 cl, 6 ex

FIELD: chemistry.

SUBSTANCE: method of separating acrylic and benzoic acid contained in a gas mixture of products of partial oxidation into acrylic acid, during which acrylic and benzoic acid are first converted to a liquid phase from which, using a thermal separation technique, components with lower boiling point than benzoic and acrylic acid are then separated and acrylic acid is then separated from the remaining liquid phase by crystallisation. The method does not require energy consuming separation techniques. There is basically no fusion of benzoic acid into a crystal during crystallisation, which forms the basis of marked efficiency of the procedure according to the disclosed method.

EFFECT: less energy consuming separation technique.

22 cl, 1 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to method of obtaining aqueous acrylic acid from flow of gaseous material, which includes the following stages: a) supply of gaseous flow into condenser, where flow of gaseous material includes at least acrylic acid, water and formaldehyde; and b) operation of condenser and obtaining gaseous output flow, which includes non-condensed components released from the upper part of condenser, and condensed flow of aqueous acrylic acid, including acrylic acid, which is discharged from condenser mud-box, where flow of aqueous acrylic acid includes not more than 0.1 wt % of formaldehyde in terms of total weight of flow of aqueous acrylic acid. Flow, which contains (met)acrylic acid can represent flow of raw product of catalytic oxidation of at least one C2-C4-alkane or -alkene.

EFFECT: method is characterised by high concentration of (met)acrylic acid and lower concentration of formaldehyde, ie not higher than 0,1 wt %, than in aqueous (met)acrylic acid, obtained by application of separation methods known before.

8 cl, 1 dwg, 2 ex

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