Method of preventing precipitation of fumaric acid when producing maleic acid anhydride

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of preventing precipitation of fumaric acid when producing maleic acid anhydride comprising the following steps: a) absorption of maleic acid anhydride from the mixture of products obtained as a result of partial oxidation of benzene, olefins having 4 carbon atoms and n-butane, in an organic solvent or water as an absorbent, b) separation of maleic acid anhydride from the absorbent, containing fumaric acid, wherein the absorbent regenerated thus, which contains fumaric acid, is completely or partially catalytically hydrogenated and completely or partially returned to the absorption step (a), wherein fumaric acid is hydrogenated to amber acid.

EFFECT: method enables to prevent precipitation on equipment components and the resulting clogging, cleaning procedures and switching off.

16 cl, 8 ex

 

The proposed invention relates to a method of preventing deposition of fumaric acid in obtaining maleic anhydride (MA), where µa is absorbed from the mixture of primary products in an organic solvent or water as a sink, then MCA is separated from the absorber and thus regenerated absorber or its partial stream is catalytically hydronaut and completely or partially return to the stage of absorption (a).

Proposed according to the invention the method is used to improve the industrial production of maleic anhydride. The anhydride of maleic acid is a valuable source substance, component polymers or by hydrogenation of the ICA through the intermediate stage of succinic acid anhydride (YAK) is used to obtain gamma-butyrolactone (GBL), butanediol (BDO) and tetrahydrofuran (THF).

The anhydride of maleic acid can be obtained by partial oxidation of hydrocarbons, such as butane or benzene. Of the exhaust gas partial oxidation containing the anhydride of maleic acid, the desired product is usually absorbed in the solvent. Along with MCA absorb the following, contained in the exhaust gas oxidation components, such as, for example, water. Water interacts with the anhydride of maleic acid to obtain the maleic acid to Ara, in turn, isomerized to fumaric acid. Fumaric acid is very poorly soluble in water or organic solvents by dikilitas, which forms a precipitate and this can clog the equipment, such as, for example, columns, exchangers, pumps, pipes, etc.

In modern technology, there are already proposals to avoid such obstructions caused fumaric acid.

So, in the international patent application WO 96/29323 describe what the absorber containing fumaric acid, washed with water extractant, so as to avoid the sediment. The disadvantage of this method is the high costs that are necessary to mix the wash water in an industrial plant for producing dicarboxylic acids having 4 carbon atoms, or derivatives thereof, and again split phase. Besides the inevitable loss of valuable product and solvent makes the process is not economical. In addition, due to the additional water supply to the process is further enhanced by the formation of fumaric acid.

Proceeding from this prior art, the basis of the proposed invention is to prevent deposition on the details of the equipment and as a result of this contamination, finishing and cleaning work, as well as disable when a method of producing dicarboxylic which the slot, having 4 carbon atoms, and/or their derivatives.

The solution to this problem is a method of preventing deposition of fumaric acid in obtaining maleic anhydride with the following stages:

a) absorption of maleic anhydride from a mixture of starting materials in an organic solvent or water as a sink,

b) separating maleic anhydride from the absorber,

moreover, the regenerated thus absorber fully or partially catalytically hydronaut and completely or partially return to the stage of absorption (a). Preferably the partial flow hydronaut and fully return to the stage of absorption (a).

Proposed according to the invention, the method prevents the above-mentioned disadvantages by means of what is contained in the absorber fumaric acid hydronaut with hydrogen to produce succinic acid. In an unexpected way in the presence of solid fumaric acid reaches high selectively at low pressures and small quantities of used catalyst. Even deposition fumaric acid, already educated in the pipes or other parts, again separated.

Proposed according to the invention a method of hydrogenation may include the additional step, which includes obtaining the ICA by casting the oxidation of suitable hydrocarbons. Suitable flow of hydrocarbons are benzene, olefins having 4 carbon atoms (for example, n-butenes, the flow of raffinate having 4 carbon atoms) or n-butane. Particularly preferably used n-butane, as it is cheap, cheap used stuff. Methods partial oxidation of n-butane describe, for example, in Ullmann''s Encyclopedia of Industrial Chemistry, 6thEdition, Electronic Release, Maleic and Fumaric Acids-Maleic Anhydride.

Thus obtained reaction release, the mixture of ingredients is then absorbed in water or preferably in a suitable organic solvent as an absorber or a mixture thereof, and the organic solvent at atmospheric pressure preferably is at least 30°C higher boiling point than the MCA.

Containing the anhydride of maleic acid gas stream from the partial oxidation can be mixed with the solvent (absorbent) in a variety of ways at a pressure (absolute) of 0.8 to 10 bar and temperatures from 50 to 300°C at one or more stages of absorption: (i) the introduction of a gas stream in a solvent (for example, through a nozzle for introducing a gas or gas rings), (ii) the introduction of solvent into the gas stream and (iii) contact of the jet between the current upward gas flow and current down solvent in tray or Packed column. In vcentre options you can use the apparatus for getpagesize, well-known specialist in this field. When applying solvent (absorber) have to pay attention to, especially when getting μa, so that it does not interact with the educt used µa. Suitable absorbers are: tricresylphosphate, dibutylated, butylmalonate, high molecular weight waxes, aromatic hydrocarbons with molecular weight between 150 and 400 and a boiling point above 140°C, such as, for example, dibenzoylbenzene; alkylphenate and dialkyl phthalates with alkyl groups having from 1 to 18 carbon atoms, such as dimethylphthalate, diethylphthalate, dibutyl phthalate, di-n-propietat and di-ISO-propietat, undecimated, vondelstraat, methylphthalic, ethylphthalate, butylphthalate, n-propietat or ISO-propietat; complex dialkyl ethers having from 1 to 4 carbon atoms, other aromatic and aliphatic dicarboxylic acids, such as complex dimethyl ether dimethyl-2,3-naphthalene-dicarboxylic acid, dimethyl ether complex dimethyl-1,4-cyclohexane-dicarboxylic acid; complex alkalemia esters having from 1 to 4 carbon atoms, other aromatic and aliphatic dicarboxylic acids, for example dimethyl ether complex of 2,3-naphthalene-dicarboxylic acid, dimethyl ether complex of 1,4-cyclohexane-dicarboxylic acid, long-chain fatty acids having, for example, from 4 to 30 carbon atoms, high-boiling ethers, such as simple dimethyl ether of polyethylene glycol, for example a simple tetraethylethylenediamine ether.

Preferred is the use of phthalates.

The solution obtained after processing the absorber has, in General, the content of the ICA from about 5 to 400 grams per liter.

The flow of exhaust gas remaining after processing the absorber contains along with water first of all by-products of the preceding partial oxidation, such as carbon monoxide, carbon dioxide, neprevyshenie butane, acetic acid and acrylic acid. The flow of exhaust gas contains almost no µa.

Then dissolved µa removed or separated from the absorber. This can occur when the use of hydrogen at or not more than 10% above the pressure subsequent hydrogenation µa to THF, BDO or GBL preferably at temperatures from 100 to 250°C and pressure (absolute) from 0.8 to 30 bar. In the Stripping column see the temperature profile, which is obtained from the boiling points of the ICA at the top and almost not containing µa absorber in the bottom of the column at the proper pressure column and the prescribed dilution with carrier gas (hydrogen). To prevent loss of solvent above the flow of raw MCA can be a distillation in which ADCI.

An alternative to the preferred distillate with hydrogen can be separated MCA dissolved in the absorber, in the distillation setup with pressure, in General, from 0.01 to 5 bar and temperatures from 65 to 300°C. And the distillation can be conducted in one stage or several stages, for example, in a distillation apparatus (separating devices) with a single stage or multiple stages, such as, for example, columns with multiple stages of separation, such as distillation columns, Packed columns, plate bubble cap columns or Packed columns.

Thus, the anhydride of maleic acid is removed from the absorber in a vacuum or pressures, which correspond to the pressure hydrogenation or constitute not more than 10% above this pressure.

Regenerated, driven away from the lower part of the distillation or Stripping columns, almost not containing µa absorber serves then as proposed according to the invention, the hydrogenation and hydronaut on the hydrogenation catalyst preferably at temperatures from 20 to 300°C., particularly preferably from 60 to 270°C., and particularly preferably from 100 to 250°C and at pressures (absolute value) is preferably from 0.1 to 300 bar, particularly preferably at from 0.5 to 50 bar, particularly preferably from 0.8 to 20 bar.

The content in the regen is new at the stage b) absorber fumaric acid (the total number of homogeneous dissolved and suspended fumaric acid) before proposed according to the invention stage hydrogenation is usually from 0.01 up to 5% of the mass. Most often returned to the absorber has the content of fumaric acid between 0.02 and 2 wt.%. The molar amount of hydrogen for proposed according to the invention stage of the hydrogenation, in General, is chosen so that there is at least one mol of hydrogen to one mole of fumaric acid. However, the excess hydrogen is not critical. Moreover, hydrogen can be dissolved, in addition may be hydrogen gas. After proposed according to the invention stage of the hydrogenation of the content of fumaric acid, as a rule, is below 0.1 wt.%, preferably below 0.05 wt.%. The content of fumaric acid should only be so high that at a given temperature was attended by the homogeneous solution.

Proposed according to the invention the method can be performed periodically, semi-continuous or continuous. Preferred is continuous.

The hydrogenation takes place in the liquid phase heterogeneous catalysts that can be firmly placed or suspended, and preferred are firmly located catalysts (catalysts for fixed bed).

Preferably used catalysts contain at least one metal from the seventh, eighth, ninth, tenth or eleventh group PE iadicicco table of the elements or their compounds, such as, for example, the oxides. More preferably used according to the invention, the catalysts contain at least one element selected from the group consisting of rhenium, iron, ruthenium, cobalt, rhodium, iridium, Nickel, palladium, platinum, copper and gold. Most preferably used according to the invention, the catalysts contain at least one element selected from the group consisting of Nickel, palladium, platinum, ruthenium and copper. Even more preferably used according to the invention, the catalysts contain palladium, platinum, ruthenium or Nickel.

Fit is especially at least one heterogeneous catalyst, it is possible to apply at least one of the above metals (active metal) in the form of a metal itself, in the form of a Raney catalyst and/or printed on plain media. If you apply two or more active metals, they may be present separately or in the form of alloy. When it is possible to use at least one metal as such and at least one other metal in the form of a Raney catalyst or at least one metal as such and at least one other metal applied to at least one carrier or at least one metal in the form of a Raney catalyst and at least, one of the CSOs other metal, deposited on at least one carrier or at least one metal as such and at least one other metal in the form of a Raney catalyst and at least one other metal applied to at least one media device.

The hydrogenation catalyst used in the form of molded articles, preferably in the form of Strakhov, ribbed Strakhov, tablets, rings, balls or gravel.

Applied catalysts can also be, for example, so-called catalyst deposition. Such catalysts can be obtained by the fact that their catalytically active components are precipitated from salt solutions, in particular solutions of their nitrates and/or acetates, for example, by adding solutions of alkali metal and/or alkaline earth metal and/or carbonates, such as insoluble hydroxides, oxide hydrates, basic salts or carbonates, the obtained precipitates are then dried and then they are turned by calcination at temperatures of in General from 300 to 700°C., especially from 400 to 600°C., into the corresponding oxides, mixed oxides and/or mixed-valence oxides that restore by treatment with hydrogen or gases containing hydrogen, at temperatures of from 50 to 700°C., especially from 100 to 400°C., to the corresponding metal and/or oxide compounds lower is largely oxidized and transferred to own a catalytically active form. And restore, as a rule, up until no longer formed any water. Upon receipt of the catalyst deposition, which contain material media, the precipitation of the catalytically active components can occur in the presence of the respective materials of the carrier. The catalytically active components can precipitate preferably simultaneously with the materials of the carrier from the corresponding salt solutions.

Preferably used hydrogenation catalysts which contain a catalytic hydrogenation metals or metal compounds deposited on the material of the carrier.

Besides the above-mentioned catalysts deposition, which in addition to the catalytically active components contain additional material media, for proposed according to the invention the method is suitable, in General, the materials of the carrier, in which components with catalytic-hydrogenation step is applied to the material of the carrier, for example, by impregnation.

The method of applying the catalytically active metal on the carrier is generally not critical and can be done in a variety of ways. The catalytically active metals can be applied to these materials carriers, for example, by impregnation with solutions or suspensions of the salts or oxides of the respective elements, drying and posleduyushego the recovery of metal compounds to the corresponding metals or compounds of lower oxidation state by using a reducing agent, preferably hydrogen or complex hydrides. The next opportunity of applying the catalytically active metals to these media is that the media is impregnated with solutions of salts, easily degradable thermally, for example, using nitrates or easily degradable thermally complex compounds, such as carbonyl-complexes or hydrido-complexes of the catalytically active metal and impregnated so the media is heated to temperatures from 300 to 600°C for thermal decomposition of the adsorbed metal compounds. This thermal decomposition is preferably in a protective gas atmosphere. Suitable protective gases are, for example, nitrogen, carbon dioxide, hydrogen or noble gases. You can also precipitate a catalytically active metal on the carrier for the catalyst by thermal spray or flame spraying. The content of catalytically active metals to these catalysts on a carrier is in principle not critical to the success of proposed according to the invention method. In General, a higher content of catalytically active metals lead these catalysts on the medium to higher volume conversion-time than the lower. In General, applied catalysts on a carrier, the content of catalytically active metals in which the ranges from 0.01 to 90 wt.%, preferably from 0.1 to 40 wt.%, calculated on the total weight of the catalyst. As these contents are related to the whole catalyst, including the material of the carrier, and a variety of media materials have very different specific weight and specific surface, it is also possible that these data may be understated or overstated without negative impact on the outcome of the proposed according to the invention method. Of course, you can also apply a few of catalytically active metals on the appropriate material medium. In addition, the catalytically active metals can be applied to a carrier, for example, by methods described in the German patent application DE-A 2519817, European patent applications EP-A 1477219 or EP-A 0285420. According to the above-mentioned sources in the catalysts, the catalytically active metals are present in the form of alloys, which receive heat treatment and/or recovery, for example, by impregnation of the material of the carrier salt or complex of the aforementioned metals.

Based on the toxicity of chromium catalysts preferably used catalysts containing chromium. Of course for use in proposed according to the invention the method is technically suitable and appropriate well-known specialist in this field, chromium catalysts, sredstv is E. this but not getting the desired benefits in particular the production of a technical nature and terms of the environment.

Activating a catalyst deposition and catalyst on the carrier may occur in situ in the beginning of the reaction due to the present hydrogen. Preferably the catalysts are activated separately before applying them.

As materials of the carriers, as for catalyst deposition, and catalysts on the media, you can apply the oxides of aluminum and titanium, zirconium dioxide, silicon dioxide, clays, such as montmorillonite, bentonite, silicates, such as, for example, silicates of magnesium or aluminum, zeolites, such as, for example, a structure type ZSM-5 or ZSM-10, or activated carbon. The preferred media materials are aluminum oxide, titanium dioxide, silicon dioxide, zirconium dioxide and activated carbon. Of course also as carriers for catalysts used in proposed according to the invention the method can serve as a mixture of different materials carriers. Also suitable are metal media on which the besieged catalytic hydrogenation metals, such as copper, which is precipitated, for example, palladium, platinum or ruthenium from the corresponding metal salts dissolved in water.

The most preferred proposed coz the ACLs to the invention catalysts are the catalysts on a carrier, which contain Nickel, platinum and/or palladium, with the most preferred carriers are activated carbon, alumina, titanium dioxide and/or silicon dioxide, or a mixture thereof.

Used according to the invention the heterogeneous catalyst can be applied as a suspension of catalyst and/or as a fixed catalyst proposed according to the invention method.

Proposed according to the invention stage hydrogenation is preferably carried out in one or more separate reactors. In the preferred embodiment, to a separate reactor for hydrogenation stage hydrogenation proposed according to the invention method serves exhaust gas-hydrogen from the hydrogenation of ICA to obtain YAK, GBL, THF and/or BDO.

However, proposed according to the invention, the hydrogenation can also occur within a Stripping column to separate µa from the absorber. In a particular embodiment, a Stripping column, preferably at the bottom, where the concentration of MCA is already below 1 wt.%, has a fixed catalyst, for example, in the form of a catalytic nozzles.

If the framework proposed according to the invention method stage hydrogenation is carried out with at least one suspension catalyst, hydronaut preferably, ENISA least one reactor mixing at least one bubble column and/or bubble column with nozzles or in combination of two or more identical or different reactors.

The concept of "different reactors" means various types of reactors, and reactors of the same type, which differ, for example, by its geometry, such as, for example, its size and/or its cross-section, and/or hydrogenation conditions in the reactors.

According to the proposed method is used, at least one hydrogenation reactor, which is selected from the group consisting of tubular reactors, shaft reactors, reactors with internal heat output, shell-and-tube reactors, and reactors with fluidized bed.

Moreover, at the stage hydrogenation employing multiple reactors connected in parallel or sequentially.

If the framework proposed according to the invention method, the hydrogenation is carried out with at least one fixed catalyst, it is preferably used at least one tubular reactor, such as, for example, at least one shaft reactor and/or at least one shell-and-tube reactor, and a reactor can be operated in the mode of settling tank or reactor with irrigated catalyst bed. When using two or more reactors can exploiter the VAT, at least one mode of the tank and at least one mode of operation with irrigated catalyst bed.

If as a catalyst under hydrogenation proposed according to the invention, a method is used heterogeneous catalyst as a suspension catalyst, it is separated after hydrogenation, preferably through at least one stage of filtration. Separated thus the catalyst can be returned to the stage hydrogenation.

Released during the hydrogenation of heat, as a rule, do not remove. However, if necessary, it can take from used according to the invention the reactor from the inside, for example, through cooling coils and/or externally, for example, through at least one heat exchanger.

If the hydrogenation is performed on at least one suspended catalyst, the processing time is in General from 0.01 to 10 hours, for example, from 0.5 to 5 h, preferably from 0.5 to 2 h and especially preferably from 0.1 to 1 o'clock And insignificant use according to the invention the main reactor and an additional reactor, or an additional and other reactors. For all of these embodiments, the total processing time is in the above areas.

If the framework proposed in accordance with the invention, a method is proposed according to ISO is retenu stage hydrogenation is conducted in a continuous way, at least one fixed catalyst, the load of catalyst (kg inflow/liter of catalyst × h) is, in General, from 0.05 to 1000, preferably from 0.1 to 500, and particularly preferably from 0.5 to 100. Moreover, the insignificant, the use according to the invention the main reactor and an additional reactor, or an additional and other reactors. For all of these embodiments, the total load is within the above areas. Under the influx understand the return absorber containing fumaric acid.

Others present in the inflow components are primarily those that are at the stage of absorption is also absorbed by the solvent. Mention should be made of, for example, maleic acid, MCA, alkyl substituted derivatives of maleic acid, acrylic acid, methacrylic acid and acetic acid. In addition, there are the products of hydrogenation of proposed according to the invention method, such as succinic acid anhydride and succinic acid. Besides, there are other compounds that can be formed from the solvent, and they may depend on the nature of the solvent. If used, for example, phthalates, along with the anhydride of phthalic acid and its complex monoamine also possible esters of the aforementioned acids.

To remove high-boiling comp is required, such as, for example, succinic acid, in a particular embodiment, can be subjected to fractional distillation stream is recycled to the absorber after stage hydrogenation and before returning to the stage of absorption (a).

In addition, succinic acid, which was formed by proposed according to the invention, the hydrogenation can be removed as such or in the form of an anhydride of succinic acid from the absorber methods known in the art, for example by partial condensation, condensation, distillation and steam, similar to the above-mentioned Stripping ISA.

Proposed according to the invention the method is explained in more detail using the following examples.

Examples:

Comparative example 1

1A) test equipment

Used equipment consists of a supply to melt µa supply of water before the circulation pump, distillation column heated bottom and reverse separator for separating maleic anhydride (MA) between the two heat exchangers, and pressure regulator. Due to concomitant heating temperature in all parts of the equipment is at least 70°C.

The recirculation flow of 3 l/h of dibutyl phthalate is heated at a pressure of 1.2 bar before distillation column up to 200°C, and after the pressure regulating conduct in distil anionwu column. When the pressure in the column 0.2 bar absolute temperature in the lower part 230°C. After cooling to 90°With the recirculation flow taken through an overflow tube in the lower part of the column, in the loop add about 0.3 kg/h of MCA in the form of a melt, and about 15 g/h of water. MCA and most of the water is distilled off via the top part of the column with reflux 1 (distillate). The distillate consists of mainly MCA, as well as minor quantities of water and maleic acid. The tool is further for 4 days. With daily sampling, visual inspection, and gas chromatography analysis shows that the device is formed of the suspended solid matter in the form of fumaric acid. After 4 days clogged the pressure regulator and the device stops. After unloading cycle in pipelines and heat exchangers are deposits of fumaric acid.

Example 2

2A) test equipment

Used equipment 2A) differs from the test apparatus 1A) of comparative example 1 built after the overflow tube of the lower part of the column and before connected to the column heat exchanger tubular reactor, heated or cooled by oil (10 ml), which is filled with 3 mm strangle catalyst consisting of 5 wt.% palladium on charcoal, and flows in a mode with orosa the th layer of the catalyst.

When is usually equal to the test conditions and proportions in contrast to comparative example 1 in a reactor at a temperature of about 180°With introducing a stream of hydrogen of about 0.5 l/H. the Device is operated within 10 days. At this time there is no clogging. Daily samples by visual assessment and gas chromatographic analysis did not show any solids. In the distillate along with MCA are also the anhydride of succinic acid, maleic acid and succinic acid.

Proposed according to the invention examples 3-5

Repeat proposed according to the invention example 2, and example 3 instead of palladium on charcoal is used to 0.15 wt.% palladium on aluminum oxide in example 4 to 10 wt.% Nickel on charcoal in example 5 to 0.15 wt.% platinum on alumina. In all the examples get the same effect, as proposed according to the invention example 2.

Example 6

Repeat proposed according to the invention example 2, but in the first three days in the reactor do not add hydrogen. Samples from circulation after 2 days show the content of solids in fumaric acid. After 3 days, as proposed according to the invention example 2, introducing hydrogen in an amount of about 0.5 l/H. With the new sampling the next day by visual estimation or gathermate the specific analysis of fumaric acid were not detected.

This example shows that when proposed according to the invention also can be gidrirovanii once formed fumaric acid, which could secede.

Comparative example 7

7a) test equipment

Used equipment working under pressure, consists of a supply to melt µa supply of water before the circulation pump and working with hydrogen Stripping column (Stripping column) for separation of the ICA between the two heat exchangers, and pressure regulator. Due to concomitant heating temperature in all parts of the equipment is at least 70°C.

The recirculation flow of 1.5 l/h of dibutyl phthalate is introduced into the Stripping column at a temperature of 200°C by regulating pressure of about 10 bar absolute). In the lower part of the Stripping columns, filled with rings process (5 mm), at a pressure of 9 bar (absolute) pump 1.5 Nm3/h of hydrogen at a temperature of about 150°C. After cooling to 90°With the recirculation flow taken through an overflow tube in the lower part of the Stripping columns, add in a cycle of about 0.1 kg/h of MCA in the form of a melt, and about 5 g/h of water. The product from the top of the Stripping column (hydrogen, µa and a small amount of dibutyl phthalate) hydronaut catalyst copper/aluminum oxide at temperatures of from 230 to 260°C and a pressure of 9 bar t is ovcata reactor in a known manner to obtain a THF.

After a period working 6 days the device was stopped due to blockage in the heat exchanger after the overflow tube in the lower part of the Stripping column. After unloading cycle in pipelines and heat exchangers are deposits of fumaric acid.

Example 8

8A) test equipment

Used equipment 8A) is different from the test apparatus 7a) of comparative example 7 that in the lower part of the Stripping tower ring process replace 50 ml of 0.15 wt.% palladium on aluminium oxide.

When is usually equal to the test conditions and proportions as in comparative example 7, the device is operated within 10 days. At this time there is no clogging. Daily samples do not detect solids. Subsequent hydrogenation to obtain a THF no negative impact as a result of hydrogenation of fumaric acid in circulation dibutyl phthalate, i.e. succinic acid or anhydride of succinic acid have no harm.

1. The way to prevent sediment fumaric acid in obtaining maleic anhydride with the following stages:
a) absorption of maleic anhydride from the mixture of products obtained by partial oxidation of benzene, olefins having 4 carbon atoms or n-butane, in an organic solvent or water is used as absorber,
b) separating maleic anhydride from the absorber containing fumaric acid,
moreover, the regenerated thus the absorber containing fumaric acid, fully or partially catalytically hydronaut and completely or partially return to the stage of absorption (a), when fumaric acid is subjected to hydrogenation to succinic acid.

2. The method according to claim 1, wherein the succinic acid after hydrogenation is separated from the absorber, regenerierung at the stage b).

3. The method according to claim 1 or 2, characterized in that a partial stream of the regenerated absorbent hydronaut, and this partially hydrogenated stream is fully return.

4. The method according to claim 1 or 2, characterized in that used hydrogenation catalyst containing at least one of the metals of the seventh, eighth, ninth, tenth or eleventh group of the periodic table of elements.

5. The method according to claim 1 or 2, characterized in that hydronaut at a temperature of from 20 to 300°C and a pressure of from 0.1 to 300 bar.

6. The method according to claim 1 or 2, characterized in that at least one hydrogenation reactor selected from the group consisting of tubular reactors, shaft reactors, reactors with internal heat output, shell-and-tube reactors and fluidized bed.

7. The method according to claim 1 or 2, characterized in that on the stage Gadirov the Oia apply several reactors, connected in parallel or sequentially.

8. The method according to claim 1 or 2, characterized in that the material of the carrier of the hydrogenation catalyst is selected from oxides of aluminum and titanium, zirconium dioxide, silicon dioxide, clays, montmorillonites, bentonites, silicates, zeolites, activated carbon or mixtures thereof.

9. The method according to claim 1 or 2, characterized in that the hydrogenation catalyst contains one or more of the following metals selected from rhenium, iron, ruthenium, rhodium, iridium, Nickel, palladium, platinum, copper and gold or their compounds.

10. The method according to claim 1 or 2, characterized in that the hydrogenation catalyst used in the form of molded articles, preferably in the form of Strakhov, ribbed Strakhov, tablets, rings, balls or gravel.

11. The method according to claim 1 or 2, characterized in that the anhydride of maleic acid is removed in stage b) of the absorber with the help of hydrogen.

12. The method according to claim 1 or 2, characterized in that the anhydride of maleic acid in stage (b) by distillation is separated from the sink.

13. The method according to claim 1 or 2, characterized in that the absorber is chosen from the group consisting of tricresylphosphate, dibutylamine, high molecular weight waxes, aromatic hydrocarbons with molecular weight between 150 and 400 and a boiling point above 140°C, preferably of dibenzoylbenzene, complex dialkylamino esters have the General from 1 to 4 carbon atoms in the alkyl, aromatic and aliphatic dicarboxylic acids, preferably dimethyl ether complex of 2,3-naphthalene-dicarboxylic acid and/or dimethyl ether complex of 1,4-cyclohexane-dicarboxylic acid, methyl esters of long chain fatty acids having from 14 to 30 carbon atoms, high-boiling ethers, preferably simple dimethyl ether of polyethylene glycol, preferably of tetraethyleneglycol, and alkylphenate and diallylphthalate with alkyl groups having from 1 to 18 carbon atoms, preferably from the group of dimethylphthalate, diethylphthalate, dibutyl phthalate, di-n-properplace and di-ISO-properplace, underinflate, vondelstraat, metalplate, utilitate, butylphthalate, n-properplace and ISO-properplace.

14. The method according to claim 1 or 2, characterized in that the anhydride of maleic acid is removed from the absorber in a vacuum or pressures, which correspond to the pressure hydrogenation or constitute not more than 10% above this pressure.

15. The method according to claim 1 or 2, characterized in that the method is carried out periodically, semi-continuous or continuously, preferably continuously.

16. The method according to claim 1 or 2, characterized in that the separation of maleic anhydride occurs by partial condensation, condensation, steam or distillation.



 

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9 cl, 46 tbl, 36 ex

FIELD: physics; operation.

SUBSTANCE: invention relates to the chemical industry, particularly to the automatic control systems and can be used for temperature support of the reaction mixture in chemical reactors. The system of automatic temperature profile support in the reactor with distributed constants in maleic anhydride production contains two control systems: cascade automatic control system (ACS) of coolant temperature control in the reactor and ACS of benzene-air mixture fed to the reactor where the correction signal is inleted according to reaction mixture temperature. The correction signal represents the sum of the signals about reaction mixture temperature in the measurement points positioned along the reactor height multiplied to the weight factor determined intuitively or from optimization problem solution. Then the correction signal is compared with assignment signal on the functional generator serving as algebraic adder. The invention allows to increase the temperature support accuracy in the reactor at maleic anhydride production.

EFFECT: increasing of the temperature support accuracy in the reactor.

2 cl, 2 dwg

The invention relates to a method for producing a cyclic anhydride or a nitride of hydrocarbon and oxygen-containing gas in the presence of an appropriate catalyst, in particular to a method of reducing or eliminating the risk of explosion or fire in the headspace of the reactor system, in which there is a formation of the anhydride, or nitrile of hydrocarbon and oxygen

The invention relates to a method for obtaining succinic anhydride used in the production of pharmaceuticals, insecticides, as a hardener of epoxy resins, in analytical chemistry

The invention relates to organic synthesis

The invention relates to a method for producing succinic anhydride, which can find application in the chemical industry

The invention relates to anhydrides of dibasic acids, in particular to an improved method for producing anhydride, endo-norbornene-2,3-dicarboxylic acid, which is used for the synthesis of unsaturated polyesters, alkyd resins

FIELD: chemistry.

SUBSTANCE: method of synthesis of manganese (II) fumarate through direct reaction of metal with acid is presented. The process is carried out in a vertical type bead mill with mass ratio of beads to the reaction mixture equal to 1:1, and the liquid phase is a solution of fumaric acid in an organic solvent with content of acid of 0.70-1.80 mol/kg. Manganese is taken in stoichiometric amount with acid or in deficiency of up to 5%. The process is started by loading the liquid phase solvent and acid and preparation of the acid solution in a bead mill, after which metal is loaded and the process is carried out at temperature ranging from 25 to 35°C while preventing spontaneous increase of temperature through forced cooling and controlling through sample taking and determination of manganese salt in the samples and residual amount of acid until attaining values close to calculated values during quantitative conversion of the reagent in deficiency. After that stirring and cooling are stopped. The suspension of the reaction mixture is separated from the glass beads, cooled to temperature between 5.2 and 6.2°C and filtered. The filtering residue is washed with the liquid phase solvent, cooled to approximately the same temperature, and taken for purification by recrystallisation. The filtrate and the washing solvent are returned to the repeated process.

EFFECT: method is easy to implement, the end product can be easily separated and there are no auxiliary materials which contaminate the obtained product.

2 cl, 11 ex

FIELD: chemistry.

SUBSTANCE: iron (II) fumarate can be used in different fields of chemical practice, in analytical control and in scientific research, through direct reaction of iron with fumaric acid in the presence of a catalyst, where the catalyst used is molecular iodine in amount of 0.025 to 0.1 mol/kg of the initial load, iron is taken in large excess in form of shells on the entire height of the reactor, false bottom and blade mixer, as well as in form of crushed cast iron and(or) reduced iron powder, the liquid phase solvent used is butylacetate, in which iodine and fumaric acid are at least partially dissolved, where fumaric acid is taken in amount of 0.8 to 1.2 mol/kg of the initial load, loading is done in the sequence: glass beads, liquid phase solvent, fumaric acid, iodine, and then crushed cast iron and(or) reduced iron powder; the process is started at room temperature and is carried out in a vertical type bead mill with ratio of mass of beads to mass of crushed cast iron and(or) reduced iron powder equal to 4:1, at temperature ranging from 18 to 45°C while bubbling air with flow rate of 0.95 l/min-kg of the liquid phase and using forced cooling and controlling using a sampling method until complete exhaustion of the loaded acid for formation of salt, after which stirring and cooling are stopped, the reaction mixture is separated from glass beads and unreacted crushed cast iron and(or) reduced iron powder and filtered, the residue is washed with butylacetate and taken for recrystallisation, and the filtrate and washing butylacetate are returned to the repeated process. Amount of acid used in extracting the product (without loss during purification) ranges from 89 to 96.5%, which depends on conditions for carrying out the process.

EFFECT: improved method of producing said product.

8 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing manganese (II) fumarate from manganese metal and its oxide (III) through direct reaction of the metal and its oxide Mn2O3 with an acid in the presence of a liquid phase and a stimulating iodine additive in a vertical type bead mill with glass beads as grinding agent. The metal and its oxide are loaded in molar ratio (2±0.1):1 in total amount of 7.87 to 10.93% of the mass of the load. Acid is added with 15 to 25% excess of the calculated value, equal to the number of moles of metal and twice the number of moles of metal oxide in the load. The base of the liquid phase is isoamyl alcohol, in which the iodine stimulating additive is dissolved in amount of 0.02 to 0.05 mol/kg. Glass beads are loaded first, in mass ratio to the reaction mixture of 1.35:1, and then later the liquid phase solvent, acid and stimulating additive, and after brief stirring, metal oxide and metal, stirring all the while. Taking this moment as the beginning of the process, forced cooling is introduced right away. Operating temperature is stabilised in the range 33 to 45°C and in this mode, the process is carried out until virtually quantitative conversion of metal and its oxide to the target salt, after which stirring and forced cooling are stopped. The reaction mixture is separated from the glass beads, cooled to temperature 5 to 6°C and kept at that temperature for 1 to 2 hours. The solid phase of the target salt is filtered off and washed with isoamyl on a filter cooled to approximately the same temperature, after which it is taken for purification by recrystallisation. The filtrate and the cleaning solvent, containing excess acid, the bulk of the stimulating additive and a certain amount of dissolved target salt, are returned for loading in the repeated process. The process is carried out in light temperature conditions. The target substance can be easily separated.

EFFECT: design of a low-waste method, which allows for obtaining target product from available manganese oxide with an easy to implement process.

9 ex

The invention relates to organic synthesis

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing unsaturated carboxylic anhydrides of general formula I, in which R is an unsaturated organic residue having 2-12 carbon atoms by re-anhydridising an aliphatic carboxylic anhydride through reaction with a carboxylic acid of general formula II, in which R is as defined above, in an apparatus consisting of a reaction region and a rectification column, wherein a) the reactants are fed into the reaction region in stoichiometric ratios, b) the carboxylic acid formed as a by-product is removed from the reaction mixture, c) the carboxylic anhydride of the formula I is subsequently distilled off, d) the unconverted reactants are recycled into the reaction region, e) the reaction region contains a heterogeneous catalyst and f) one or more polymerisation inhibitors are added.

EFFECT: improvement lies in that stoichiometric excess of one of the reactants is avoided, formation of secondary components is prevented and complete conversion of reactants is achieved.

6 cl, 1 dwg, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method for continuous production of unsaturated carboxylic acid anhydrides of general formula R-C(O)-O-C(O)-R (I), in which R denotes an unsaturated organic residue having 2 to 12 carbon atoms, by re-anhydrising an aliphatic carboxylic acid anhydride with carboxylic acid of general formula r-cooh (II), in which R is as described above, in a reactor and subsequent separation of the obtained anhydride in a fractionation column with a top, middle and bottom region, where a) inert boiling oil is fed into the bottom of the column, b) reactants are fed into the reactor in stoichiometric ratio, c) carboxylic acid which is a by-product is removed from the top part of the column, d) unreacted reactants are returned into the reactor and e) a product of formula (I) is obtained through a side outlet, preferably between the middle and bottom region of the column, wherein the process is carried out in the presence of a polymerisation inhibitor.

EFFECT: complete conversion of reactants, high purity of products and significant inhibition of polymerisation.

10 cl, 2 ex, 1 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method for distillation purification of polymerisable compounds selected from monomers with at least one reactive double bond or other reactive functional groups, using boiling oil as an intermediate agent, which is a high-boiling, inert, long-term thermally stable substance, where the boiling oil is at the bottom of the fractionation column and boiling point of said oil ranges from 150 to 400°C at 1013 mbar, wherein the intermediate agent, without further purification, is returned into the apparatus and at most 10% of the intermediate agent per end product is taken out, and concentration of the polymerisable compound is reduced via heat exchange with boiling oil vapour in the direction towards the lower part of the column and thus in the direction of rising temperature. The method enables to prevent polymerisation of the end product. The invention also relates to use of boiling oil as an intermediate agent, which is a high-boiling, inert, long-term thermally stable substance with boiling point of 150-400°C at 1013 mbar, at the bottom of the fractionation column for distillation purification of polymerisable compounds selected from monomers with at least one reactive double bond or other reactive functional groups, wherein the intermediate agent, without further purification, is returned into the apparatus and at most 10% of the intermediate agent per end product is taken out, and concentration of the polymerisable compound is reduced via heat exchange with boiling oil vapour in the direction towards the lower part of the column and thus in the direction of rising temperature.

EFFECT: improved method for distillation purification of polymerisable compounds.

6 cl, 1 dwg, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method for continuous production of unsaturated carboxylic acid anhydrides of general formula R-C(O)-O-C(O)-R (I), in which R denotes an unsaturated organic residue having 2-12 carbon atoms, through reaction of a ketene of general formula R'-CR"=C=O (III), in which R' and R" are identical or different and represent hydrogen or an alkyl residue having 1-4 carbon atom, with an unsaturated carboxylic acid of general formula R-COOH (II), which the value of R is as given above, in which in an apparatus comprising a reaction zone (1) for reaction of ketene with the unsaturated carboxylic acid of general formula II, a reaction zone (2) for further reaction of the formed mixture of crude anhydride and a fractionation column with a top, a middle and a bottom region, into the still of which inert boiling oil is fed, a) the unsaturated carboxylic acid of general formula II is fed into the reaction zone (1), b) the formed mixture of crude anhydride from step a) is fed into the next reaction zone (2) lying outside or inside the column or contained in the reaction zone (1), c) the mixture of crude anhydride from step b) is purified in the fractionation column, d) the formed carboxylic acid distilled in the top part of the column and returned once more for production of ketene, e) unconverted reagents and intermediate products formed are returned to reaction zone (1) and/or (2) and f) a product of formula I is obtained between the middle and the bottom region of the fractionation column, where the process is carried out in the presence of a polymerisation inhibitor, and a heterogeneous catalyst is used in reaction zone (2).

EFFECT: method enables complete conversion of the unsaturated carboxylic acid used and obtain high-purity unsaturated anhydride and carboxylic acid.

9 cl, 1 dwg, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of increasing utilisation factor of silver during adsorption and removal of decyl iodide from acetic acid which contains decyl iodide as an impurity, by passing acetic acid through a packed layer of a cation-exchange resin at temperature 50°C or lower, where the cation-exchange resin is a macroporous-type polystyrene resin with average particle size ranging from 0.3 to 0.6 mm and average pore size from 15 to 28 nm, and where the resin has sulpho groups, and silver occupies 40-60% of the active sites of sulpho groups.

EFFECT: high utilisation factor of silver during adsorption and removal of decyl iodide from acetic acid.

FIELD: chemistry.

SUBSTANCE: method of extracting acrylic acid from a liquid phase uses acrylic acid as the main component and desired product and methacrolein as the by-product, where the liquid phase used is obtained via at least one fuzzy separation from a gaseous mixture of products of gas-phase partial oxidation on a heterogeneous catalyst of at least one tri-carbon precursor of acrylic acid, where the liquid phase is crystallised with enriched acrylic acid in the formed crystallised product and methacrolein in the residual liquid phase.

EFFECT: method enables efficient separation of methacrolein from acrylic acid.

14 cl, 1 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: method involves reacting derivative of maleic anhydride with n-aminodiphenylamine while heating to temperature not above 90°C. The derivative of maleic anhydride used is alkenyl succinic anhydride or a mixture of alkenyl succinic anhydrides of general formula: , where n=6,8,10,12,14,16,18 with molar ratio of maleic anhydride links to n-aminodiphenylamine equal to 1.0-1.05:1.0.

EFFECT: improved processing characteristics of antioxidant, characterised by low dropping point, high efficiency for emulsion-polymerised rubber and latex, protection of said rubber from thermal-oxidative ageing.

1 tbl, 7 ex

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