The method of obtaining acetic acid and/or methyl acetate and method for improving the stability and/or prevent deactivation of the catalyst upon receipt of acetic acid and/or methyl acetate

 

The invention relates to a method for producing acetic acid and/or methyl acetate in the liquid phase, in the presence of carbon monoxide and the catalytic system, and to a method of increasing the stability and lifetime of the used catalyst. At the first stage in the conditions of the carbonylation of methanol flows through the reaction of isomerization of methylformate with the formation of acetic acid and/or methyl acetate. The catalytic system comprises at least one halogenated promoter and at least one catalytic compound based on iridium. In the second stage, called stage flash evaporation, carry out partial evaporation obtained at the first stage of the reaction medium in the separator. In coming out of the separator Nisporeni liquid fraction support the total content of formic acid and methylformate at least equal to 1 wt.%, preferably from 1 to 50 wt.%, more preferably from 1 to 30 wt.%, with respect to this liquid fraction. The invention allows to obtain acetic acid and/or methyl acetate in the increased stability of the catalytic system, even at low values of water content and extremely low pressures of carbon monoxide in the reaction zone. Those who decontamination in the reaction zone. 2 N. and 19 C.p. f-crystals, 3 tables.

The technical field to which the invention relates

The present invention relates to a method of improving the stability and/or prevent deactivation of the catalyst in the ways of producing acetic acid and/or acetate, as well as a complete method for producing acetic acid and/or acetate, which includes this method.

More specifically, the object of the present invention is an improved method, which can improve the stability and/or to prevent deactivation of the catalyst in the implementation of the methods of obtaining acetic acid and/or methyl acetate by isomerization of methylformate and, if necessary, by carbonylation of methanol in the presence of a catalytic system containing at least one halogenated promoter and at least one connection based on iridium.

The invention relates also to the special conditions in which this method of stabilization is applicable particularly advantageous way.

The level of technology

In the industrial production of known and different methods are used to obtain acetic acid, including a method based on the reaction of the carb is I one of the reagents, in the presence of a homogeneous catalytic system. Another approach to obtaining acetic acid is isomerization of methylformate. This reaction is usually carried out in the presence of a catalytic system in a homogeneous phase. Finally, according to another method performed simultaneously carbonylation of methanol and isomerization of methylformate.

By itself, the way carbonylation using rhodium widely known in the industrial production and is the subject of many publications and inventions, such as disclosed in U.S. patent No. 3769329 and No. 3813428.

In the European patent document No. 618183, 618184 and 785919, 759022 describes how to carbonylation in the presence of catalytic systems on the basis of iridium, which optionally contains rhodium.

Industrial used method carbonylation using iridium and ruthenium described in the European patent document No. 643034.

Relatively recently in the patent document France No. 2746794 and in the international application WO 97/35829 was a new approach, which provides for the reaction of isomerization of methylformate in the presence of iridium.

In parallel, in patent document France No. 2746795 and in the international application WO 97/35828 what I isomerization reactions of methylformate and the carbonylation reaction of methanol.

These different modes of production of acetic acid is usually carried out continuously in plants that contain three main zones. The first zone corresponds to the reaction zone and contains the reactor under pressure, in which the carbonyl and/or isomerization in the liquid phase. The second zone is a zone of separation of the formed acid. This operation is performed by the partial evaporation of the reaction mixture in the evaporation apparatus of the instant action, which hereinafter for brevity referred to as an evaporator and in which is supported a pressure lower than in the reactor. The vaporized portion is then sent to the third area where cleaned obtained acetic acid. This area contains various distillation columns, in which the received acetic acid is separated from the water, reagents and by-products. The remainder of the mixture in liquid form at the exit of the evaporation zone contains a catalyst and is directed by the recirculated back to the reactor.

Professionals in this field know that the units for production of acetic acid and/or methylformate second area is usually the place where it can happen decontamination and/or evaporation of the catalyst of the independence of the m partial pressure of carbon monoxide in this area and are compounded by a factor of low water content. In U.S. patent No. 5237097 the proposed solution is the introduction of carbon monoxide in the feed to the evaporator the liquid to sustain in the evaporator sufficient partial pressure.

In patent document France No. 2726556 and in the international application WO 96/14286 describes how the introduction of carbon monoxide in the effluent from the evaporator the liquid fraction for the regeneration of the catalyst, directed by recirculated back to the reactor.

In the European patent document EP 0616997 and the appropriate divisional application EP 0786447 proposed improved method of producing acetic acid by carbonylation catalyst containing iridium. The improvement lies in the fact that in coming out of the evaporator liquid fraction support the water content of below 0.5 wt.% in order to stabilize the catalyst present in this fraction.

In the known solutions related to the prior art, do not offer any improvement in stabilization of the catalyst in producing acetic acid and/or methyl acetate by isomerization of methylformate and, in necessary cases, the carbonylation of methanol with iridium in the catalyst.

The creators of the us is and can be solved by maintaining sufficient total content of formic acid and methylformate in coming out of the evaporator liquid fraction. This condition is sufficient even when there is a particularly low content of water in this part of the installation and even when the water content is below 0.5 wt.% in relation to Nisporeni liquid fraction and even with almost complete absence in the environment of carbon monoxide. Before this, the experts believed that to ensure the stability of the catalyst requires a relatively high water content, at least above 0.5 wt.%, and what the minimum content of carbon monoxide allows to stabilize the catalyst.

The invention

Thus, in accordance with its first aspect the present invention is directed to improved methods for obtaining acetic acid and/or methyl acetate using a catalyst system based on iridium, with improvements designed to improve stability and/or prevent deactivation of the catalyst.

The proposed method of stabilization can significantly reduce the water content in the reaction medium, and in the evaporation zone, which gives a considerable advantage in economic terms, as it allows to reduce costs for the final recovery of the obtained product. Thus, this stabilization ka is the Etat, which contains improvements aimed at stabilizing the catalyst, and according to which use is also particularly low content of water.

According to the second aspect of the invention relates to a complete method for producing acetic acid and/or methyl acetate in satisfactory conditions for both stabilization of the catalyst, and water content that gives double benefit in economic terms compared with the known methods.

More specifically, in the first of these aspects, the invention relates to a method of improving the stability and/or preventing deactivation of the catalyst in the ways of producing acetic acid and/or methyl acetate, according to which the exercise in the first phase, called the reaction stage, in the liquid phase, in the presence of carbon monoxide and the catalytic system containing at least one halogenated promoter and at least one catalytic compound based on iridium, at least the reaction of isomerization of methylformate, and in the second stage, called stage flash evaporation, carry out partial evaporation obtained at the first stage of the reaction medium in the separator, called separator is idcol fraction of the total content of formic acid and methylformate at least equal to 1 wt.% this liquid fraction, preferably from 1 to 50 wt.%, more preferably from 1 to 30 wt.% this liquid fraction.

In accordance with its second aspect the invention relates to a method of obtaining acetic acid and/or methyl acetate, containing the first stage, called the reaction stage, which is carried out in liquid phase, in the presence of carbon monoxide and the catalytic system containing at least one halogenated promoter and at least one catalytic compound based on iridium, at least the reaction of isomerization of methylformate, at least the reaction of isomerization of methylformate, and the second stage, called stage flash evaporation and providing partial evaporation obtained at the first stage of the reaction medium in the separator, called separator evaporator. According to this method is printed from the specified separator evaporator Nisporeni liquid fraction support the total content of formic acid and methylformate at least equal to 1 wt.% this liquid fraction.

According to this method, the water content of the effluent from the evaporator liquid fraction of support, mostly below 5 wt.%, preferably below 2 wt.% and even Bolo has a way of stabilizing and maintaining the activity of the catalyst and the full method of obtaining acetic acid and/or acetate, refer to the processes of production of acetic acid and/or acetate, in which the reaction is carried out in the first reaction stage, necessarily includes the reaction of isomerization of methylformate in the liquid phase in the presence of carbon monoxide and the catalytic system containing at least one halogenated promoter and at least one catalytic compound based on iridium.

According to a preferred variant embodiment of the invention in each of its two aspects of this reaction is the isomerization of methylformate carried out simultaneously with the reaction of the carbonylation of methanol, with the specified carbonylation of methanol can occur through absorption of carbon monoxide introduced to the reaction stage.

According to another preferred variant of the invention, the method of stabilizing and maintaining the activity of the catalyst according to the invention is carried out by controlling the water content in the liquid fraction leaving the evaporator. This content is supported mainly below 5 wt.%, preferably below 2 wt.% this liquid fraction leaving the evaporator.

As mentioned above, you can get better results on stability kacestvennoe advantage in comparison with known methods of the prior art, as also mentioned above.

According to a particularly preferred variant of the invention, a method of obtaining acetic acid and/or methyl acetate, except for the first stage, called the reaction stage and the second stage, called stage evaporation, contains the third stage, called stage of the treatment and recovery of acetic acid and/or methyl acetate from the vaporized fractions obtained during the partial evaporation.

During this phase, acetic acid and/or methyl acetate is separated from the light compounds such as water, formic acid, using a variety of means known to specialists in this field.

According to a particularly preferred variant of the invention, the formic acid is separated from acetic acid by reactive distillation by supplying methanol to the bottom of the distillation column, and discharge of treated acetic acid from the base of the column, and a mixture of methanol with methylformate from the head of the column.

In the subsequent description will be particularly defined optimal conditions for both reaction medium and a liquid medium outlet of the evaporator. These conditions are valid as for a method of stabilizing and maintaining the CA activity is sanija in the case when not given the opposite instructions, the term “reaction” describes the complex reactions that occur in the reaction zone. It covers isomerization reactions and, in necessary cases, carbonylation, and all equilibrium state, which take place in the reaction zone.

Under the reaction temperature is meant the temperature at which the reaction stage.

In General the reaction is carried out at a temperature of from 150 to 250C. In particular, the reaction temperature is in the range from 175 to 210C. Preferably the temperature range is 175 to 200C.

The total pressure at which the reaction is carried out, in the General case above atmospheric pressure. In particular, the optimal value of the pressure does not exceed 200105PA, and preferably it is less than or equal to 50105PA. Pressure is expressed in Pascals absolute and measured in hot conditions, i.e. in the temperature reaction conditions.

The partial pressure of carbon monoxide is preferably kept in the range from 0.510 PA 15

Information confirming the possibility of carrying out the invention

Next will be described catalytic system.

In terms of implementation of the invention can be used all soluble compounds of iridium or its compounds, which are able to dissolve in the reaction medium. As non-limiting examples include iridium in the metallic state, simple salts of this metal, oxides and coordination complexes.

Of iridium salts typically use halogen compounds of iridium. In particular, as halogen choose chlorine, bromine or iodine, of which the latter is preferred. Thus, in the method according to the invention can be used compounds such as IrI3, GVG3, Irl3, IrI34H2O IrI4, GVG34H2O.

In the method according to the invention can be used oxides, selected from the group consisting of IrO2Ir2O3HN2O.

As for the soluble coordination complexes of iridium, the most frequently used compounds containing the gene chosen by chlorine, bromine or, most preferably iodine. Not excluded the use of soluble iridium complexes, the ligands are selected from, for example, organo-phosphorus or organo-nitrogen compounds.

Among well-known specialists in the field of coordination complexes, the most suitable for implementing the method according to the invention, it is possible to specify, as non-limiting examples, the following connections: Ir4(CO)12, Ir(CO)2I-2Q+, Ir(CO)2Br-2Q+, Ir(CO)2Cl-2Q+; in these formulas, Q may represent, in particular, hydrogen, group, NR4PR4R, is selected among hydrogen and/or hydrocarbon radical.

These catalysts can be obtained by any method known to specialists in this field. For example, you can refer to European patent documents EP 657386 and 737103, which describes obtaining catalytic solutions based on iridium, suitable for implementing the method according to the invention.

It should be noted that the reaction in accordance with the invention can be implemented by means of a catalytic system, which contains only one compound of iridium, but may also contain complement the 618183.

When using a catalytic system containing rhodium atomic ratio of rhodium to iridium may vary within a wide range: from 0.01 to 99.

In the General case, the concentration of iridium or combination (iridium + rhodium in the reaction medium ranges from 0.1 to 100 mmol/l, preferably from 1 to 20 mmol/L.

The iridium compounds or mixtures (iridium + rhodium) can be added catalyst selected from the metals of group VIII of the periodic system of elements.

In addition to the above compounds, the catalytic system in accordance with the invention contains a halogenated promoter. It can be present in the form of a single halogen or in combination with other elements, such as, for example, hydrogen, methyl radical or an acetyl.

As the halogen is usually chosen chlorine, bromine or iodine, and the iodine is preferred.

As halogenated compounds, which can also be used as promoters, you can specify iodine, idiscovered acid, methyliodide, acetylide.

Preferably as a halogenated promoter use methyliodide.

According to another variant of the method according to the invention the halogenated promoter is introduced into the reaction mixture in the form of pressurizat the firm to allocate in the reaction medium, under the action of the halogen or halogen acid, a hydrocarbon radical specified halogenated promoter. The data connection or present in the environment or introduced into it for this purpose.

As non-limiting examples of suitable intermediates, you can specify a connection selected from the group consisting of methanol, dimethylether, methyl acetate or methylformate, which are used separately or in a mixture.

The number present in the reaction mixture of the halogenated promoter is preferably equal to or less than 20 wt.% with respect to the total weight of the mixture. Preferably the content of the halogenated promoter is equal to or less than 15 wt.%.

It should be noted that the promoter is injected partially or completely in the form of the intermediate product, the number of intermediate or a mixture of the promoter with the semi-product is that it allows to achieve the above values.

In addition to these compounds, the reaction medium contains water, formic acid, methylformate, methyl acetate and acetic acid with the following preferred content by weight, which preferably can withstand at the same time.

The water content in the reaction medium preferably comprising a reaction medium, preferably below 15 wt.%, more preferably below 12 wt.%.

The content of methylformate in a reaction medium, preferably below 20 wt.%.

According to a particular variant embodiment of the invention, the content of methyl acetate in the reaction medium below 40 wt.%, preferably below 20 wt.%.

The content of acetic acid in the reaction medium of at least 25 wt.%.

The way to improve stability and/or prevent deactivation of the catalyst, and a method of obtaining acetic acid and/or methyl acetate in accordance with the invention can be performed in the presence of iodide in the form of having a solubility in the reaction medium. The iodides may be introduced into the reaction medium as such or in the form of compounds which can form soluble iodides.

Under the iodides here means only ions, that is not included covalent iodides (such as halogenated promoter) or itestosterone acid.

Thus, led to a mixture of iodides such as chosen from mineral or organic iodides.

As mineral iodides, you can specify mainly the iodides of alkaline-earth or alkali metals, the latter are preferred. Among them may be named potassium iodide, the e contain at least organo-phosphate group and/or at least one organo-nitrogen group, which reacts with compounds based on iodine for producing ions containing the halogen. As an example, you can specify iodide tetraphenylporphine, iodide N-methyldiethylamine.

As compounds capable of forming soluble in the reaction medium, the iodides, can be called, for example, carboxylates, hydroxides of alkaline or alkaline-earth metals such as lithium acetate, potassium and sodium.

It should be noted that the iodides may be of different origin, different from the above.

For example, these compounds can be formed from impurities such as alkali or alkaline-earth metals, which are present in the source materials used to prepare the catalyst solution.

The iodides may also be formed in the reaction of the corrosion of metals.

The way to improve stability and/or prevent deactivation of the catalyst, and a method of obtaining acetic acid and/or methyl acetate in accordance with the invention is preferably carried out in the presence of corrosion of metals when the content is below a few hundred ppm (M. D.), preferably below 200 m D. Corrosion metals are iron, Nickel is local methods, such as, for example, selective deposition, liquid-phase extraction, transmission through the ion exchange resin.

Next will be described the conditions in the zone of the evaporator.

Optimal temperature is maintained between 80With up to 200With a total pressure of from 0 to 20105PA in absolute Pascals.

The components present in the liquid phase at the outlet of the evaporator, are identical to those contained in the reaction medium described above.

The main distinguishing feature of the invention consists in maintaining the overall content of formic acid and methylformate at least equal to 1 wt.% coming out of the evaporator liquid fraction, preferably from 1 to 50 wt.%, more preferably from 1 to 30 wt.%.

The optimal relationship of the various components in percentage by weight relative to the effluent from the evaporator liquid fraction is kept preferably at the same time and comprise the following values:

- the content of the halogenated promoter is below 20 wt.%, preferably below 15 wt.%,

- the water content is below 5 wt.%, preferably below 2 wt.%, moreover, in accordance with special advantages variant implementation of the stability of the cat is edocfile below 12 wt.%,

- the content of methylformate support below 20 wt.%,

according to a specific example of implementation, the acetate content of less than 40 wt.%, preferably below 20 wt.%,

the content of acetic acid of at least 25 wt.%.

Coming out of the evaporator Neispravna the liquid fraction may contain iodides in the form ionic compounds, soluble in this fraction (specified in the description of the reaction medium).

The content of carbon monoxide in the evaporator is not zero. Carbon monoxide can come from subject to evaporation of the reaction medium in the form of dissolved or captured stream FROM. In addition, it can be injected directly into the liquid fraction leaving the evaporator and directed to the recirculation system into the reactor. In any case, the partial pressure of carbon monoxide in the evaporation zone below the partial pressure of carbon monoxide, which is maintained in the reaction zone.

When implementing the above method of producing acetic acid or acetate these two products contained in the effluent from the evaporator the gas phase is separated from the light compounds, water, formic acid and other contaminants, for example, by fractional distillation in one the circulation back into the reactor.

In the preferred embodiment of formic acid is separated from acetic acid by reactive distillation with feed of methanol in the lower part of the distillation column. This formed mailformat mainly directed by recirculated back to the reactor and treated thus acetic acid lead away from the base of the column.

In General, advantages of the invention are particularly advantageous manner during continuous operation of the process.

The following examples are purely illustrative and in no case not restrictive.

EXAMPLES

I - stability Tests

I-1. Used equipment

All experiments were conducted in resistant to high pressures transparent tube length of 16 cm and an inner diameter of 0.7 cm, which creates a total volume of 6 ml

This tube is equipped with:

input for gas supply, allowing purge gas to the arch of the tube, in the General case, carbon monoxide,

- means for heating the tube by means of an electric furnace temperature control,

- means for shaking using the tilt table.

I-2. Preparation of the reaction mass.

*Preparation of the catalyst solution by buggenum by heating to 150C, under pressure of carbon monoxide 5010 PA within 4 h of the thus Obtained catalyst solution contains approximately 2.6% of iridium (or 26000 memorial plaques or mg/kg).

*Preparation of the reaction mixture to test for stability by weighing and mixing of the various components:

- acetic acid, methyl acetate, under the conditions,

catalytic solution, taking into account bring them the amount of acetic acid,

and, for experiments 1-10, formic acid and methylformate.

*Thus prepared reaction mass (initial composition) were analyzed.

I-3. General description of the process

The tube gave 4 g of the reaction mass, shook the tube and blew three times relevant gas, then the tube was left under the pressure of this gas value of 2.2105PA.

As a gas used carbon monoxide for experiments 1, 2, 3, 4, 5, 7, 8, a, b, C, D; the air for experiments 6, 9 and 10. The tube was shaken for another 20 C. the Tube was weighed to verify the absence of leaks. Next, the tube was placed in an electric furnace and heated for the desired time before the desired temperature (130 or 150(C) without shaking, and then heating the stun is italinate test. After this was carried out by visual inspection of the tube and its contents: the type, color, sediment/sludge. Were samples required for analysis of the reaction mass before (initial stage) and after the test for stability (the final stage).

I-4. Methods of analysis

the concentration of iridium was measured by spectroscopy with inductively coupled plasma (ICP spectroscopy);

the water concentration was determined by the Karl Fischer method;

- composition of organic matter was measured by chromatography in the gaseous phase;

- stability of iridium, expressed as a percentage of the solution was calculated by the formula

error estimation stability of iridium is10%.

I-5 Results

I-5. a) stability Tests at 130

Examples 1-6 and A-D at a temperature of 130And tables a and b of the test results on the stability of the

Experiments 1-6 correspond in accordance with the invention. Conditions and results of experiments are shown in table A.

Experiments A-D are comparative examples and are not identical variants in accordance with the invention. The conditions and results of the experiments lead is Oceania. The tables contain the following data.

the composition of the reaction mixture wt.%, including the following components:

acetic acid (Asón), formic acid (HCOOH),

the acetate (Asome), methylformate (Naome),

methyliodide (SN3), water (H2O)

the iridium content in M. D. (mg/kg)

the absolute gas pressure (RNO) in 105PA

- duration of heating at 130

- the percentage of iridium in the solution after a period of heating.

Analysis of tables a and b according to the results of experiments 1-6

In further combination (formic acid + mailformat) will be called “formyl compounds”.

Examples 1 and experiments at 0.4% water

For about the same initial value content of acetate and under the conditions (11 and 2%) and in the presence of 0.4% of water, after heating for 120 min at a temperature of 130With the stability of iridium in example 1 is 95% against 31% in comparative example A.

The initial presence of 13% “formyl compounds significantly stabilizes the catalyst.

Examples 2 and In the experiments in the absence of water

In example 2, the initial value of content close to the values in example 1; in the absence of water after 15 min of heating outstay water and formyl compounds comparative example shows the stability of the catalyst up to 72%.

Example 3: experience in the absence of water

Example 3 reduction of the initial content formyl compounds” to 4.7% in the absence of water allows you to keep an excellent stability of iridium after heating at 130C for 15 min (100%).

Example 4: experience with 16.7% “formyl compounds”

In contrast to the experience 3, the initial content “formyl compounds increased to 16.7%. After 60 min of heating at 130With ensured stability of iridium 96% in the presence of only 0.3% of water.

Examples 5, C and D experiments with increased content under the conditions

These three experiment was carried out at a temperature of 130C for 120 min under an absolute pressure of 2.2105PA monoxide, which corresponds to the General conditions of the method.

In example 5, in the presence of the initial content of 5.7% “formyl compounds” and 5.1% under the conditions, the stability of iridium was 96%.

In the absence of “formyl compounds” and for essentially equivalently values of water content and acetate comparative examples C and D show:

in the case of low initial content of 1.3% under the conditions (experience With) the stability of iridium substantially addictive, known from the prior art), but doesn't achieve the value of stability obtained in experiment 5 (96%).

Example 6 in the absence of carbon monoxide

This experiment was conducted using air as the gas in the absence of CO after 60 min of heating at 130With the initial content of 5.3% “formyl compounds to keep the stability of iridium at the level of 90% compared with the values of the stability of iridium in the comparative experiments, equal:

- 31% after 120 min of heating (comparative experiences) with the initial content of iodide and methyl acetate, identical to the experience of 6,

- 27% after 120 min (comparative experience With).

I-5. b) stability Tests at 150

In the table are given the results and experiments on stability in accordance with the invention (7, 8, 9 and 10) and comparative experience (S) at 150C.

Examples 7, 8 and E at 150With a table With the results of the stability tests

The experiments were carried out in the same conditions as the previous examples, except that the heating temperature was 150Instead of 130C.

Conditions and results of experiments are given in table C.

For sod is I “formyl compounds” (the initial content of 6.3% for experience 7 and 13.2% for experience 8) for the stability of iridium, which were, respectively, 93% and 99% against 40% in the comparative experience of E, which was carried out in the absence of these compounds.

Further, in the aspect of the influence of increasing temperature from 130With up to 150With, you can compare pairs of experiments 3 and 7, 2 and 8, and E in order to ascertain the stability of iridium (under equal conditions on the composition and duration):

this is a very small decrease in stability in the experiments corresponding to the invention of:

- 100%93% 100%99%

significant in the comparative experience of E:

- 72%40%.

It is convincing proof of the influence and importance formyl compounds”: formic acid and methylformate.

Examples 9 and 10 at 150With and in the absence of carbon monoxide table With

These experiments are designed to show a positive effect of a small increase in water content, as well as excellent stability of iridium in the complete absence of carbon monoxide, when there are formyl compounds”.

Compared with experiments 7 and 8 (in the presence of CO) and for the duration of the reaction 15 min in experiment 9, with ="https://img.russianpatents.com/chr/176.gif">(6) up to 150With (experiment 10) does not cause the fall of the stability of iridium (90% in experiment 6 against 93% in experiment 10), and these two experiments conducted in air with a duration of 60 minutes reaction

II - example of a complete method in accordance with the invention

Example 11

The reaction of isomerization and carbonylation with recirculation of the catalyst In the autoclave HastelloyB2 containing the catalytic solution prepared as described above for the previous examples, the method continuously introduced various components of the reaction medium: acetic acid, methylformate, methanol, methyl acetate, methyliodide and, in some cases, water. Coming out of the reactor stream is sent to the zone where the evaporated one fraction containing the product acetic acid. Neispravna fraction containing the catalyst was sent with a recirculation system in the reactor. The vaporized fraction are condensed, and it was liquid output products.

In this experience in coming out of the evaporator Nisporeni liquid fraction supported the total concentration of formic acid and methylformate 6.5% and a water content of 1%.

The composition of the reaction medium in a stable mode was determined by the HRO is>the ode to 1.3%

Methanol with 0.1%

The acetate 16,1%

Methyliodide 9,7%

Formic acid 4,3%

Mailformat 1,6%

Acetic acid is the Rest up to 100%

The concentration of iridium 2050 mg/kg (M. D.)

The temperature was kept equal to 1900,5C.

The total pressure in the reactor was kept equal to 2.4 MPa20 kPa.

The partial pressure of carbon monoxide maintained constant and the corresponding 1,05 MPa; used WITH had a purity above 99%.

Calculate the rate of formation of acetic acid during the two reactions, isomerization of methylformate and carbonylation of methanol is produced by the balance of input and output of liquid products in the zone and the evaporation zone, taken within a certain period of time (between 40 and 43 hours of operation), in relation to the flow of communications filed during the same period of time, after stabilization of the chemical regime. Calculation of the rate of carbonylation produced by the absorption of carbon monoxide by the reaction of carbonyl (balance input/output).

The obtained value of the rate of isomerization of 1,4 mol.h-1l-1the yield of acetic acid and the rate of carbonylation of 16.4 mol.) - Rev. ATA.

Parameter TOF (abbreviation of the English term Turnover Frequency frequency of turnover), calculated as the ratio of the total rate of the two reactions (17.8 mol.h-1l-1) to the concentration of catalyst in the reaction medium (0,01067 mol. l-1), reaches 1670 mol.h-1.

In this experiment, with a total duration of operation of 100 hours between the beginning and end of the experience did not reveal a loss of the catalyst due to the deposition or decontamination. This fact is established on the basis of the periodically conducted analysis of the concentration of iridium in the reaction medium and leaving the evaporator is evaporated fraction and Nisporeni liquid fraction (directed by recycling to the reactor).

Claims

1. The way to improve stability and/or prevent deactivation of the catalyst in the methods of production of acetic acid or methyl acetate, whereby in the first stage, called the reaction step is carried out in liquid phase, in the presence of carbon monoxide and the catalytic system containing at least one halogenated promoter and at least one catalytic compound based on iridium, at least the reaction of isomerization of methylformate, and viatape reaction medium in the separator, called separator evaporator, characterized in that in coming out of the separator evaporator Nisporeni liquid fraction support total content of formic acid and methylformate at least equal to 1 wt.% this liquid fraction, preferably from 1 to 50 wt.%, more preferably from 1 to 30 wt.% with respect to this liquid fraction.

2. The method according to p. 1, characterized in that it is carried out in the composition of the method of producing acetic acid and/or methyl acetate in a continuous mode.

3. The method of obtaining acetic acid and/or methyl acetate, comprising the first stage, called the reaction stage, which is carried out in liquid phase, in the presence of carbon monoxide and the catalytic system containing at least one halogenated promoter and at least one catalytic compound based on iridium, at least the reaction of isomerization of methylformate, and the second stage, called stage flash evaporation, partial evaporation obtained at the first stage of the reaction medium in the separator, called separator evaporator, characterized in that that coming from the specified separator evaporator Nisporeni liquid fraction support total retained the WMD of PP.1-3, wherein the first step further comprises the carbonylation reaction of methanol.

5. The method according to p. 1 or 4, characterized in that the specified liquid fraction support the water content below 5 wt.%, preferably below 2 wt.% in relation to a specified liquid fraction leaving the evaporator.

6. The method according to p. 5, characterized in that the specified water content support below 0.5 wt.% in relation to a specified liquid fraction leaving the evaporator.

7. The method according to any of paragraphs.1-6, characterized in that the specified second stage partial evaporation followed by a third stage of the treatment and recovery of acetic acid and/or methyl acetate from the vaporized fraction obtained at this stage partial evaporation.

8. The method according to p. 7, characterized in that the third stage of the treatment and recovery of formic acid is separated from acetic acid by reactive distillation, by supplying methanol to the bottom of the distillation column, and discharge of treated acetic acid from the base of the column, and a mixture of methanol with methylformate from the head of the column.

9. The method according to any of paragraphs.1-8, characterized in that the reaction medium of the first stage maintain the concentration of galogenirovannyie first stage maintain the concentration of formic acid, constituting less than 15 wt.%.

11. The method according to any of paragraphs.1-9, characterized in that the reaction medium of the first stage maintain the concentration of methylformate, constituting less than 20 wt.%.

12. The method according to any of paragraphs.1-11, characterized in that the reaction medium of the first stage maintain the concentration of acetate, comprising less than 40 wt.%.

13. The method according to any of paragraphs.1-12, characterized in that the reaction medium of the first stage maintain the concentration of acetic acid of at least 25 wt.%.

14. The method according to any of paragraphs.1-13, characterized in that the halogenated promoter is chosen from iodine compounds and their intermediates.

15. The method according to p. 14, characterized in that the halogenated promoter is chosen from the group consisting of iodine, methyliodide, idiscovered acid and acetylated.

16. The method according to p. 15, characterized in that the halogenated promoter is methyliodide.

17. The method according to any of paragraphs.1-16, characterized in that the catalytic system further comprises a catalytic compound based on rhodium.

18. The method according to any of paragraphs.1-17, characterized in that the total concentration of catalyst compounds or catalyst compounds sostavlyu reaction medium of the first stage using the iodides in the form ionic compounds, soluble in this medium.

20. The method according to any of paragraphs.1-19, characterized in that the reaction stage, keep the temperature from 150 to 250C, preferably from 175 to 210C, and pressures from 0 to 200105absolute PA, preferably below 50105PA.

21. The method according to any of paragraphs.1-20, characterized in that at the stage of partial evaporation keep the temperature from 80 to 200C and a pressure of from 0 to 20105absolute PA.

 

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