RU2319689C2 - Method of production of acetic acid (versions), bubble column for the method realization - Google Patents

Abstract

FIELD: chemical industry; other industries; methods and devices for production of acetic acid.

SUBSTANCE: invention is pertaining to the production process of the acetic acid by carbonylation of methanol by carbon monoxide in the bubble reactor with fluidized heterogeneous catalyst. Carbonylation reaction is conducted at concentration of the solid catalyst of no less than 100 kg/m³ in terms of the volume of the reaction system. Catalyst is formed with the help vinylpyridine resin with the complex of rhodium deposited on it. Partial pressure of the carbon monoxide in the reactor is between 1.0 and 2.5 MPa, at that the degree of exhaustion of carbon monoxide is between 3 and 15 % of the theoretical reaction volume of carbon monoxide and reduced speed of the liquid is in the interval between 0.2 and 1.0 m/s. Promoter is methyl iodide, and acetic acid and methyl acetate are used in the capacity of the dissolvent. Concentration of water in the reactor makes from 2 up to 10 mass %. The bubble cylindrical reactor column used for realization of the method has the ratio its length L to the diameter D of no less than 8 and is equipped with the external line of circulation and the heat exchanger, which is built in the line of circulation. Besides, the bubble column has the holes used for injection of carbon monoxide, which are located at least on two levels, and also has the narrowed section in the lower part of the cylindrical reactor with the inner diameter from 30 up to 70 % from the rest part of the cylindrical reactor. The hole for injection of carbon monoxide is located in the upper part of the narrowed section for fluidization of the solid catalyst, while other hole for injection of carbon monoxide is located near to the coupling of the reactor and the outer line of circulation located on the bottom of the narrow section for separation and fluidization of the solid catalyst in the outer line of circulation. Technical result of the invention is improvement of the technological form of the production process with the increased yield of the end product.

EFFECT: invention ensures improvement of the technological form of the production process with the increased yield of the end product.

22 cl, 4 tbl, 4 dwg

Description

Technical field

This invention relates to a method for producing acetic acid. More specifically, the present invention relates to a method for producing acetic acid by carbonylation of methanol with carbon monoxide in a bubble column reactor in the presence of a solid catalyst, the reaction being carried out at a high concentration of catalyst.

State of the art

The so-called "Monsanto Process" is well known for producing acetic acid, in which methanol and carbon monoxide (CO) react with each other in the presence of a noble metal catalyst. This method was originally developed in order to use a homogeneous catalytic reaction, where methanol and carbon monoxide react with each other in a reaction solution prepared by dissolving the rhodium and methyl iodide compounds, respectively, as a metal catalyst and promoter in an acetic acid solution that also contains water (Japanese Patent No. 47-3334). A modified method has been developed in order to use a heterogeneous catalytic reaction using a solid catalyst in the form of a rhodium compound (Japanese published patent application No. 63-253047). However, a homogeneous catalytic reaction is not adapted to a high reaction rate due to the low solubility of the metal catalyst in the solvent, so a huge reactor may inevitably be needed. In addition, the water in the reaction solution must be contained in a certain ratio in order to increase the reaction rate, and the selectivity of acetic acid, and the preliminary precipitation of the dissolved catalyst and, therefore, this increases the hydrolysis of methyl iodide, which serves as a promoter, reducing the yield and causing corrosion reaction apparatuses. For this and other reasons, a method was developed using a heterogeneous catalytic reaction, because he is relatively free from such problems.

Methanol carbonylation used in a heterogeneous catalytic reaction typically involves the use of acetic acid as a solvent. More precisely, methanol and carbon monoxide react with each other under pressure and at high temperature in the reactor in the presence of a solid catalyst - a compound of rhodium and a promoter - methyl iodide. The liquid reaction product extracted from the reactor results in a separation of the system, which typically includes distillation means for separating and collecting the produced acetic acid, while the remaining solution resulting from the separation is returned to the reactor. At this stage of the process, a two-phase system or heterogeneous system is located in a reactor in which the reaction solution contains acetic acid, methanol and methyl iodide as the main components among the particles of a solid catalyst (more precisely, a three-phase system containing CO bubbles). Note that the reaction solution also contains methyl acetate, dimethyl ether, hydroiodic acid and water, which are by-products of the reaction in addition to the main components described above. Particles of an insoluble resin containing a pyridine ring in the molecular structure and a rhodium complex are commonly used for solid catalysts.

A mechanically agitated continuous reactor (CSTR) is adapted to agitate the reaction solution by means of a stirrer, or a bubble column reactor is adapted to agitate the reaction solution using bubbles that can be used for the carbonylation reaction with a heterogeneous catalyst.

When a mechanically agitated continuous reactor is used, the solid catalyst particles are mixed and suspended in the reaction solution, and liquid methanol and CO gas are injected through the bottom as starting reaction materials and react with each other. Such a continuous reactor with mechanical stirring or a mixer such as a slurry reactor is accompanied by the problem of increasing the rate of CO loss, because the residence time of CO gas in the liquid is relatively short and, as soon as CO exits the liquid, moving into the gas phase in the reactor, it can be difficult dissolved in liquid again. This is additionally accompanied by the problem of the separation of the catalyst and the lifetime of the latter, because it is structurally difficult to extract only the reaction solution from the reactor, not allowing the solid catalyst to be carried away from the reactor and the catalyst particles to become smaller particles under the action of the mixer.

On the contrary, the bubbler reactor has the advantage of being free from the above difficulties and, since it is a cylindrical reactor, it is possible to provide a long residence time for the gaseous CO passing through it. When such a bubble column reactor is used, the cylindrical reactor is filled with a reaction solvent and a solid catalyst, and liquid methanol is fed through the bottom as a starting reagent, while gaseous CO is injected upward from the bottom. The injected gaseous CO forms bubbles, rising in the liquid contained in the cylindrical reactor, and the catalyst particles are also involved in the upward movement in the cylindrical reactor under the action of the gas lift and are dispersed in the liquid. As a result, the carbonylation reaction proceeds. Then, unreacted gaseous CO and the reaction solution, which contains the solid catalyst, are separated by a separator located at the top of the cylindrical reactor when they arrive there. Unreacted CO gas is collected and part of the reaction solution is taken from the top of the separator as a liquid reaction product that does not contain a solid catalyst, while the remaining part of the reaction solution that contains a solid catalyst is returned to the bottom of the cylindrical reactor by circulation under its own weight and fed again to the cylindrical reactor to complete the circulation. In known methods for carrying out a carbonylation reaction using such a bubble column reactor, gaseous CO is injected into the liquid contained in the cylindrical reactor by a jet using a nozzle located at the bottom of the cylindrical reactor in order to drive the solid catalyst particles in the reactor (Japanese published patent application No. 6-340242).

More specifically, in the aforementioned reaction step, carbon monoxide is blown into the liquid reaction mixture (containing solid catalyst particles in the case of a heterogeneous catalytic reaction) in the reactor, and gaseous components, including unreacted carbon monoxide, are recovered from the top of the reactor as off-gas. The liquid reaction mixture that has reacted is separated from the solid catalyst particles and recovered from the reactor so as to be directed to an evaporation column or evaporation vessel. In the case of the evaporation column, carbon monoxide and light components in the form of gases that were dissolved in the liquid are separated as waste gas as a result of the operation of the evaporation column, and the remaining liquid mixture is separated into crude acetic acid, which must be purified to obtain the final product, acetic acid, through successive steps, including a distillation step, and circulation of the fraction to be fed back to the reactor for circulation. In the case of an evaporation vessel, the liquid reaction mixture is separated into a gas fraction containing components that correspond to the exhaust gas, the aforementioned crude acetic acid fraction and the residual liquid fraction during a single evaporation, in which the gas fraction is purified in a subsequent distillation step and the liquid fraction is returned to the reactor . The off-gas and the circulating fraction will be obtained together with the purified acetic acid fraction, which is the final product, also in successive steps including a distillation step.

As described above, in the process of producing acetic acid, the off-gas is vented at each of the process steps, including the reaction step and subsequent separation and purification steps. The recovered exhaust gas contains not only methane and hydrogen, which are formed as a result of the reaction, and unreacted carbon monoxide, but also methyl iodide, which serves as a promoter, acetic acid, which serves as a crude product, a solvent, and other volatile substances, such as methyl acetate. For this reason, usually these useful substances are collected and returned to the reactor before the exhaust gas is burned in the waste incinerator. The gas absorption operation is usually used in order to collect useful substances from the exhaust gas and the resulting acetic acid or semi-finished products, methanol is partially used as an absorbing liquid for the gas absorption process. When the produced acetic acid is partially used as an absorbing liquid, a diffusion step is necessary to separate useful substances absorbed in acetic acid from the latter after using the latter as an absorbing liquid. The use of one of the raw materials, methanol, as the absorbing liquid provides the advantage that methanol, which was used as the absorbing liquid, can be introduced into the reactor as a result of any processing. In addition, while any efforts to cool acetic acid to improve absorption efficiency are futile due to the relatively high melting point (17 ° C) of acetic acid, methanol is preferred because it is not associated with such a problem.

Disclosure of invention

When a heterogeneous reaction using a solid catalyst is carried out in a column reactor, moving particles of the solid catalyst are likely to be blocked at the bottom of the cylindrical reactor when the concentration of the particles of the solid catalyst is high, although this problem does not occur until the concentration of the particles of the solid catalyst remains low. Further, as the reaction liquid containing the solid catalyst moves to the bottom of the cylindrical reactor under forced circulation, the circulation circuit may become clogged by the deposited particles of the solid catalyst in the circulation circuit, greatly complicating the operation. If the circulation circuit is not clogged, the solid catalyst can agglomerate in places, reducing the efficiency of producing acetic acid from the above reaction and activating side reactions.

Thus, known methods for producing acetic acid by carbonylation of methanol through a heterogeneous catalytic reaction using a solid catalyst are problematic, including that they must be carried out at a relatively low concentration of catalyst and require the use of bulky equipment to carry out the process when acetic acid is to be produced at a given speed. Thus, it is an object of the present invention to provide a method for producing acetic acid that is free from the difficulty of sticking solid catalyst particles in a reactor and clogging with precipitated solid catalyst particles in the circulation loop, so that the production efficiency of acetic acid can be reduced due to local agglomeration of the solid catalyst , and the operation for producing acetic acid can be reliably carried out only for a long period of time when catalyst concentration. The present invention is also the development of a reactor for use in this way.

Meanwhile, according to this invention, a method that involves a high concentration of catalyst, the rate at which gaseous CO is purged, is also high, and therefore the rate at which off-gas is generated is high compared to known methods. Since absorption using the starting material of methanol as the absorbing liquid is carried out to collect useful substances from the exhaust gas, the feed rate of methanol as the absorbing liquid obviously increases. However, if methanol is used to absorb the exhaust gas at a rate that is higher than the rate at which methanol is fed into the reactor as a starting material, the excess methanol needs to be simply dumped because it cannot be used as raw material. Therefore, such a high feed rate of methanol is uneconomical. In other words, it is desirable that the rate at which methanol is used to absorb gas is lower than the rate at which methanol is fed into the reactor. Thus, it should be taken into account that the efficiency of the exhaust gas absorption operation is very important for the method of producing acetic acid when methanol is used as a liquid absorbent. Thus, another objective of the present invention is to increase the efficiency of absorption of exhaust gases.

The invention provides a method for producing acetic acid by carbonylation of methanol with carbon monoxide (CO) by heterogeneous catalysis in a bubble column reactor, in which the carbonylation reaction is carried out at a concentration of solid catalyst of not less than 100 kg / m ³ , calculated on the volume of the reaction system. The solid catalyst includes a catalytic metal complex located on particles of resin. The catalytic metal usually contains 0.3 to 2.0 wt.%, Mainly 0.6 to 1.0 wt.% Of the resin particles.

According to the invention, the productivity of the carbonylation reaction increases when the concentration of the solid catalyst is not less than 100 kg / m ³ in terms of the volume of the reaction system, therefore a relatively small reactor can be used to reduce the industrial cost for the reaction. The concentration of solid catalyst is the average concentration of catalyst both in the main body of the reactor and in the circulation system.

In an aspect of the present invention, in the method according to the invention, where a concentration of solid catalyst of at least 100 kg / m ^{3 is} used, calculated on the volume of the reaction system, the partial pressure of carbon monoxide in the reactor is between 1.0 and 2.5 MPa and the degree of exhaustion of carbon monoxide is between 3 and 15% of the theoretical reaction volume of carbon monoxide, while the reduced liquid velocity is between 0.2 and 1.0 m / s.

With such a high concentration of catalyst, the partial pressure of carbon monoxide in the reactor is maintained between 1.0 and 2.5 MPa, mainly between 1.7 and 2.2 MPa, in order to maintain the mass transfer constant Kla (capacitive coefficient of the liquid phase) of the CO gas between gas and liquid, which controls the rate of the carbonylation reaction using CO, not less than a predetermined value (for example, not less than 700). The total reaction productivity decreases markedly when the partial pressure of carbon monoxide is not higher than 1.0, although the reaction rate does not noticeably increase when the partial pressure of carbon monoxide exceeds 2.5 MPa. Thus, basically, the reaction pressure can be maintained within the economic range between 1.5 and 5.9 MPa, preferably between 3.0 and 4.5 MPa, when the partial pressure of carbon monoxide is maintained within the above-defined range.

Carbon monoxide is supplied in excess to provide a suitable Kla value, and values between 3 and 15%, preferably between 5 and 10%, are selected for the rate of exhaustion of carbon monoxide (ratio of excess carbon monoxide to theoretical reaction volume of carbon monoxide). While the value improves significantly when the exhaustion rate is not lower than 3%, an exhaustion rate in excess of 15% is not preferable from an economic point of view. Because CO gas is supplied in excess, the gas lift effect is improved and promotes uniform fluidization of the solid catalyst.

In addition, the reduced velocity of the reaction liquid that rises in the reactor is maintained between 0.2 and 1.0 m / s to maintain a uniform dispersion state of the catalyst particles having a high concentration, so as to prevent a drop in productivity in the production of acetic acid and adverse reactions that contribute to the localization of the solid catalyst caused by insufficient circulation rate.

It is undesirable for the reduced fluid velocity to be higher than 1 m / s because the depletion number of the excess CO gas increases and the residence time of the CO gas becomes ineffective. In this case, to avoid these problems, you can significantly increase the reactor. If, on the other hand, the reduced liquid velocity for the reaction liquid is lower than 0.2 m / s, then the catalyst will be distributed unevenly in order to increase localized reactions, which will lead to an increase in side reactions and a decrease in catalyst lifetime.

Similarly, the reduced gas velocity for CO gas is preferred between 2 and 8 cm / s. The expression used for the reduced gas velocity refers to the average of the reduced gas velocity in the gas channel in the bottom section of the reactor and in its analog at the top of the reactor. When the reduced gas velocity is in the range defined above, the solid catalyst is uniformly dispersed in the reactor due to this velocity and the gas lift effect for CO gas is increased in the reactor so that the necessary circulation / fluidization level of the solid catalyst can be maintained on a stable basis.

According to the invention, the bubble column reactor, which is used to produce acetic acid by a heterogeneous carbonylation reaction, preferably has a ratio of length L to diameter D or L / D of at least 8, because it is necessary to provide a sufficiently long temporary gas / liquid contact and a sufficiently high level of circulation / fluidization in order to achieve a noticeable reaction efficiency. For a reactor having an L / D of at least 8, it is possible to establish a uniform circulation flow of a suspension of solid catalyst at a speed not lower than the aforementioned 0.2 m / s, because the gas delay volume in the reaction zone (lift section) increases, producing a sufficiently large the difference in density between the reaction zone and the liquid drop zone (drop zone). While either an external circulation system or an internal circulation system can be used for the bubble column reactor, it is desirable to include a heat exchanger in the circulation path in order to remove the heat generated by the reaction when using an external circulation system.

In another aspect of the present invention according to the invention, where in the method a concentration of solid catalyst of at least 100 kg / m ^{3 is} used per unit reaction volume, carbon monoxide is injected into the reactor by blowing into openings located at multiple levels.

Because carbon monoxide is injected into the reactor by blowing into holes located at numerous levels, the solid catalyst is fluidized and evenly distributed very efficiently when compared with the location at the same level, so that it is possible to work with a reaction system with a high concentration of solid catalyst of at least 100 kg / m ³ . Therefore, it is possible to reduce the size of the reactor.

The solid catalyst includes a catalytic metal complex located on particles of resin. The catalytic metal usually contains 0.3-2.0 wt.%, Mainly 0.6-1.0 wt.% From the resin particles.

The solid catalyst in the reactor can fluidize and evenly distribute even more efficiently when at least one carbon monoxide stream purged into openings at multiple levels is used as carbon monoxide purged into the holes to fluidize the solid catalyst and at least another stream carbon monoxide, blown into openings located at numerous levels, is used as a hole for blowing carbon monoxide, to create mobility of solid of catalyst in the reactor bottom. When the carbon monoxide purge port used to create mobility of the solid catalyst is located at the bottom of the reactor, this prevents the solid catalyst from settling on the bottom of the reactor. When, on the other hand, the carbon monoxide purge hole used to fluidize the solid catalyst is located in an appropriate place above the carbon monoxide purge hole used to create mobility of the solid catalyst, it is possible to move the catalyst upward in the reactor by using a gas lift effect that increases when the CO gas purged rises into a cylindrical reactor and disperses in a liquid in order to efficiently fluidize the solid catalyst. While it is preferable to position at least the carbon monoxide purge hole used to fluidize the solid catalyst and at least the carbon monoxide purge hole used to create mobility of the solid catalyst at appropriate levels, numerous purge holes can be located for fluidizing the solid catalyst and / or for mobilizing the solid catalyst where necessary.

When the carbon monoxide purge port is located at numerous levels in the manner described above, it is possible to reliably and stably perform the acetic acid production operation when the solid catalyst is used in such high concentrations that conventional bubble reaction columns having one or more carbon monoxide purge ports, located at a single level, can not work. In particular, solid catalyst deposition and blockage of the circulation line are effectively prevented when a bubble column is used with an external circulation system to circulate / supply a reaction liquid that contains a solid catalyst at the bottom of the reactor using an external circulation line and an opening for blowing carbon monoxide used to create the mobility of the solid catalyst is located near the connection of the reactor and the circulation line (i.e. the initial circulation section), cat Roe is at the bottom of the reactor and is capable of blocking the flow of solid catalyst particles.

In another aspect of the present invention, there is provided a method for producing acetic acid by carbonylation of methanol through carbon monoxide in the presence of a solid metal catalyst and characterized in that it comprises:

a reaction step leading to a carbonylation reaction by suspending a solid metal catalyst in a liquid reaction mixture containing an organic solvent composed of methanol, methyl iodide, acetic acid and / or methyl acetate and a small amount of water, and blowing gaseous carbon monoxide into the liquid reaction mixture;

the first separation stage of separation and removal of the liquid reaction mixture and gas from the reaction;

the second separation stage of conducting instant distillation by introducing a liquid reaction mixture separated in the first separation stage into the evaporation column and at the same time separating the exhaust gas and the light liquid fraction flowing from the upper section of the column and the crude fraction of acetic acid flowing from the middle section of the column and circulation fraction flowing from the bottom of the column;

the third separation stage, introducing a portion of the light liquid fraction and the crude fraction of acetic acid separated in the second separation stage into a distillation system and thereby separating the exhaust gas, the product of the acetic acid fraction, the heavy fraction and the circulation fraction;

the circulation stage of returning to the reactor the separated light liquid fraction and the circulation fraction separated in the second separation stage and the circulation fraction separated in the third separation stage;

a first absorption step of conducting gas absorption for the exhaust gas separated in the first separation step using methanol as an absorbing liquid;

the second absorption stage of gas absorption for the exhaust gas separated in the second separation stage and the exhaust gas separated in the third separation stage using methanol as an absorbing liquid at a pressure lower than in the first absorption stage;

a stage of exhaustion of the exhaust gas leaving the system after the first absorption stage of the exhaust gas leaving the second absorption stage, and a heavy fraction separated in the third stage;

that methanol, which stabilizes at a temperature of 10 to 25 ° C., is used as an absorbing liquid in the first and second absorption stages and separated so as to use 50-80 wt.% of all methanol used in the two absorption stages in the second absorption stage, and methanol, leaving after two absorption stages, is used as the raw material methanol in the reaction stage.

In another aspect of the present invention, there is provided a method for producing acetic acid by carbonylation of methanol through carbon monoxide in the presence of a solid metal catalyst and characterized in that it comprises:

a reaction step leading to a carbonylation reaction by suspending a solid metal catalyst in a liquid reaction mixture containing an organic solvent composed of methanol, methyl iodide, acetic acid and / or methyl acetate and a small amount of water and a purged carbon monoxide gas in the liquid reaction mixture;

the first separation stage of separation and removal of the liquid reaction mixture and gas from the reaction;

a second separation step for conducting flash evaporation by introducing a liquid reaction mixture separated in the first separation step into an evaporation tank while separating the gas fraction flowing from the upper section of the column and the liquid fraction flowing from the lower section of the column;

the third separation stage of the initial gas fraction separated in the second separation stage in the distillation system, and the separation of the exhaust gas, the product of the acetic acid fraction, the heavy fraction and the circulation fraction;

a circulation step of returning to the reactor a separated light liquid fraction separated in a second separation step and a circulation fraction separated in a third separation step;

a first absorption step for conducting gas absorption for the exhaust gas separated in the first separation step using methanol as an absorbent liquid;

the second absorption stage of gas absorption for the pelvis, separated in the third separation stage, using methanol as an absorbing liquid at a pressure lower than in the first absorption stage;

a stage of exhaustion of the exhaust gas leaving the system after the first absorption stage, exhaust gas leaving the second absorption stage, and a heavy fraction separated in the third stage;

that methanol, which stabilizes at a temperature of 10 to 25 ° C, is used as an absorbing liquid in the first and second absorption stages and separated so as to use 50-80 wt.% of all methanol used in the two absorption stages in the second absorption stage , and methanol, leaving after two absorption stages, is used as the raw material methanol in the reaction stage.

Brief Description of the Drawings

Figure 1 is a schematic diagram of a sample of a bubble column reaction column that can be used for the method for producing acetic acid according to the invention;

figure 2 is a schematic diagram of another sample of a bubble column reaction column, which can be used for the method of producing acetic acid, according to the invention;

figure 3 is a schematic diagram of another structural embodiment of a method for producing acetic acid according to the invention;

4 is a schematic diagram of another structural embodiment of the method for producing acetic acid according to the invention.

The best way of carrying out the invention

The present invention will be described with reference to the accompanying drawings, which illustrate a preferred embodiment of the invention.

Figure 1 is a schematic diagram of another sample of a bubble column reaction column provided with an external circulation system that can be used for the method of producing acetic acid according to the invention. When acetic acid is produced using such a reactor, firstly, the solid catalyst is loaded into the cylindrical traction section 12 of the reactor 11. The solid catalyst, which is mainly used to produce acetic acid, contains a rhodium complex based on a resin having pores and a network structure . For example, the use of a solid catalyst in which rhodium metal is made using vinyl pyridine resin is particularly preferred. Next, a mixture of a solution of methanol, which is a reaction raw material, a reaction solvent and a promoter are loaded into a reactor that is already filled with a solid catalyst. The reaction solvent may be selected from various known solvents. As a rule, it is preferable to use an organic solvent containing carbonyl groups having two or more carbon atoms as a reaction solvent. The use of acetic acid and methyl acetate is particularly preferred. An alkyl iodide, for example methyl iodide, is usually used as a promoter.

Next, a mixture of a methanol solution, which is a reaction raw material, a reaction solvent and a promoter are supplied from the bottom of the draft section 12 of the reactor 11, which is already filled with methanol, a solvent and a solid catalyst, and at the same time, CO gas is also injected through the bottom and rises. Because the injected CO gas rises like bubbles in the fluid contained in the traction section 12, the catalyst also moves upward in the cylindrical reactor using the gas lift effect. At this time, the partial pressure of carbon monoxide in the reactor is maintained between 1.0 and 2.5 MPa, preferably between 1.7 and 2.2 MPa, and the degree of depletion of carbon monoxide is between 3 and 15%, preferably between 5 and 10%, from the theoretical reaction volume of carbon monoxide. At the same time, the operating conditions are preferably chosen so that the reduced gas velocity (the average of the reduced gas velocity in the gas channel in the bottom section of the reactor and in its analog at the top of the reactor) of gaseous carbon monoxide is kept between 2 and 8 cm / s. The reported average carbon monoxide gas velocity affects the stable circulation of the catalyst and the Kla value. The circulating velocity of the liquid may fall below 0.2 m / s and / or less than 2 m / s and / or a noticeably large Kla value cannot be obtained below the performance at which the reduced average velocity of gaseous carbon monoxide is less than 2 m / s. On the other hand, carbon monoxide will be wasted to a large extent and the external pressure of the reactor will increase, making the reaction uneconomical, while the reduced average velocity of gaseous carbon monoxide will exceed 8 m / s.

The methanol carbonylation reaction with carbon monoxide is improved to produce acetic acid at a reaction temperature and a total reaction pressure that are between 170 and 190 ° C. and between 3.0 and 4.5 MPa, respectively. At the same time, methanol can partially react with methanol and / or an acetic acid derivative to alternately produce dimethyl ether, methyl acetate, water and so on as by-products. Note that the reaction rate will noticeably decrease in order to reduce productivity when the concentration of water in the reactor drops to 2 wt.%. On the other hand, the dynamic load of the apparatus for separating the product of acetic acid from the reaction solution increases, and the concentration of corrosive hydroiodic acid also increases when the concentration of water in the reactor exceeds 10% by weight. Then, bulky equipment would be required, which consequently reduces the efficiency of obtaining acetic acid. Therefore, the concentration of water in the reactor is controlled so that it is between 2 and 10 wt.%.

Using a separator section 13 located at the top of the reactor 11, a reaction solution containing a solid catalyst that rises in the traction section 12 is then partially removed from the upper part of the separator 13 as a liquid reaction product that does not contain any solid catalyst, while the remaining reaction solution that contains the solid catalyst is returned to the bottom of the reactor through the drop section of the liquid 14, so that it enters the cylindrical reactor again and continues to circulate. The reduced fluid velocity of the reaction solution, which rises into the reactor, is controlled so as to be between 0.2 and 1.0 m / s. With this arrangement, the solid catalyst is dispersed evenly and the necessary level of circulation / fluidization of the solid catalyst can be maintained on a stable basis. In addition, it is preferable to place the heat exchanger 15 in the fall zone 14, which acts as an external circulation line for the removal of heat generated, because the methanol carbonylation reaction is exothermic. The excessively supplied CO gas leaves the upper section of the separator 13 as exhaust gas and is supplied to the device for absorbing the exhaust gas 16, where it is washed with the liquid reaction raw material and fed to the reactor.

The liquid reaction product separated by separator 13 is then fed to the evaporation column 17, where the light fraction containing mainly methyl iodide, methyl acetate and water, the fraction containing mainly acetic acid, and the heavy fraction containing rhodium catalyst, acetic acid, methyl acetate, methyl iodide, water and methanol, respectively, exit from the upper section, the middle section and the bottom of the section of the evaporation column 17 to separate from each other. From the effluent fractions, the heavy components are returned to the reactor for circulation. However, heavy components include nitrogen-containing compounds, such as pyridine compounds, which are obtained as decomposition products of the vinyl pyridine resin and are released from the latter to a small extent, and if such compounds accumulate in the circulation liquid, they cause the separation of complex rhodium ions and, accordingly, a decrease in the efficiency of the catalyst . Therefore, it is preferable to process at least part of the heavy components with the nitrogen-containing compound withdrawing device 18 in order to get rid of any nitrogen-containing compounds that can cause the rhodium complex ions to detach. A device filled with an ion-exchange resin can be suitably used for such a nitrogen-containing compound 18. The gas components (mainly CO gas) dissolved in the light fraction are absorbed by methanol, which is fed to the device for absorbing the discharged gas and delivered to the reactor.

Figure 2 is a schematic diagram of another sample of a bubble column reaction vessel, also provided with an external circulation system that can be used for the method of producing acetic acid according to the invention. The reactor 21 has a cylindrical reaction section (traction section 22), where a reaction solution containing gaseous carbon monoxide and a solid catalyst and a narrowed section 28 provided at the bottom of the reactor, whose inner diameter is from 30 to 70% of the traction section 22, rises. 23 is located at the top of the traction portion 22 and is adapted to collect unreacted gaseous carbon monoxide from a reaction solution that contains gaseous carbon monoxide and solid catalysis p, and at the same time separates the liquid reaction product which contains no solid catalyst, and the reaction solution which contains the remainder of the solid catalyst. A liquid downflow zone (liquid drop section 24) for circulating the separated reaction solution that contains the remaining solid catalyst is bound at the end to the bottom of the separator section 23 and at the opposite end to the bottom of the reactor 21 to feed the reaction liquid back into the cylindrical reaction section. The heat exchanger 25 is located in the middle of the fall zone 24 to remove heat generated in the methanol carbonylation reaction, which is an exothermic reaction. The ratio of the length L to the diameter D or L / D of the reactor is preferably at least 8, because it is necessary to provide a sufficiently long temporary gas / liquid contact and a sufficiently high level of circulation / fluidization to achieve a sufficiently high reaction efficiency.

The first inlet for carbon monoxide 26 and the second inlet for carbon monoxide 27 are equipped as an inlet for injecting carbon monoxide so as to fluidize the solid catalyst in the reactor and create mobility of the solid catalyst in the lower part of the reactor, respectively. Each of the injection inlets may be in the form of a simple tube with a nozzle having a gas injection hole before the end of the tube and a ring shape or a branch pipe having gas injection holes located on the outer wall of the tube or some other shape. While it is preferable to have at least an inlet for injecting carbon monoxide so as to fluidize the solid catalyst and at least an inlet for injecting carbon monoxide to create mobility of the solid catalyst at appropriate levels, numerous inlets for injecting can be located to fluidize the solid catalyst in the reactor and create mobility of the solid catalyst where necessary.

In the reactor of FIG. 2, a second inlet for injecting carbon monoxide 27, which is used to mobilize the solid catalyst, is located at the junction with the restriction section 28, which is located at the bottom of the reactor, where the solid catalyst has the property to settle and clog the circulation line and external circulation line, node (initial circulation section) located near the lower end of the narrowing section 28. On the other hand, the first inlet for injection of carbon monoxide 26 for fluidization of solid the isator is located in the upper part of the restriction section 28 above the second inlet for injection of carbon monoxide 27. A suitable position for the first inlet for carbon monoxide 26 can be selected as a function of the cross section of the reactor 21, the concentration of solid catalyst, operating conditions of the reactor and other factors.

When acetic acid is produced using a bubble column reactor with an external circulation system, as shown in FIG. 2, the solid catalyst is first filled into the cylindrical traction portion 22 of reactor 21. The solid catalyst, which is mainly used to produce acetic acid, contains a rhodium complex supported to a base resin having pores and a mesh structure. For example, the use of a solid catalyst in which rhodium metal is applied to a vinyl pyridine resin is particularly preferred. The catalytic metal typically contains 0.3-2.0 wt.% Of the base resin. Next, a mixture of a methanol solution, which is a reaction raw material, a reaction solvent and a promoter, is poured into a reactor that is already filled with a solid catalyst. The reaction solvent may be selected from various known solvents. As a rule, it is preferable to use an organic solvent containing carbonyl groups having two or more carbon atoms as a reaction solvent. The use of acetic acid and methyl acetate is particularly preferred. An alkyl iodide, for example methyl iodide, is usually used as a promoter.

Next, a mixture from a methanol solution, which is a reaction raw material, a reaction solvent and a promoter are supplied from the bottom of the traction section 22 of the reactor 21, which is filled with methanol, a solvent and a solid catalyst, while CO gas is also injected through the first monoxide inlet carbon 26 and a second inlet for carbon monoxide 27. The gas injected through these inlets of CO rises like bubbles in the fluid contained in the traction portion 22, and the catalyst also moves towards x in a cylindrical reactor by gas lift effect.

From a reaction solution containing CO gas and a solid catalyst that rises in the traction portion 22, unreacted CO gas is collected as off-gas, while a liquid reaction product that does not contain a solid catalyst is separated from the remaining reaction solution that contains a solid catalyst in the separator section 23 located in the upper part of the reactor 21. The liquid reaction product, which does not contain a solid catalyst, is then fed to the stage of purification of acetic acid, while the reaction The solution that contains the solid catalyst is returned to the bottom of the reactor through the drop section 24, so that it again enters the cylindrical reactor for circulation.

At the same time, any excess heat generated in the methanol carbonylation reaction, which is an exothermic reaction, is removed by means of a heat exchanger 25, which is located in the middle of the liquid drop section 24 of the external circulation line.

In this bubble column design, the first carbon monoxide injection inlet 26 located at the top of the restriction section 28 mainly fluidizes the solid catalyst, while the second carbon monoxide inlet 27 located near the lower assembly of the restriction section 28 and the external circulation line, mainly creates the mobility of the solid catalyst in the lower part of the reactor, where the solid catalyst has the property to precipitate and clog the circulation line, and loosens flui disintegrates the solid catalyst in the liquid drop section. While the flow rate of CO gas, leading to each of the inlets for the injection of carbon monoxide, can be accordingly adjusted in a range that allows the reaction to be carried out on a stable basis, depending on the concentration of the solid catalyst, operating conditions, etc., the ratio the flow rate of CO gas leading to the inlet for injecting carbon monoxide, which fluidizes the solid catalyst to the flow rate of CO gas leading to the inlet for injecting carbon monoxide, cat which creates the mobility of the solid catalyst, should preferably be in the range between 70:30 and 90:10.

Taking into account the operating conditions of the bubble column reaction, the methanol carbonylation reaction is improved to produce acetic acid at the reaction temperature, total reaction pressure and partial pressure of carbon monoxide between 170 and 190 ° C, between 1.5 and 6.0 MPa and between 1.0 and 2.5 MPa, respectively. At the same time, methanol can partially react with methanol and / or the produced acetic acid alternately produces dimethyl ether, methyl acetate, water, and so on, as by-products.

Figure 3 is a schematic diagram of another structural embodiment of a method for producing acetic acid according to the invention. Referring to FIG. 3, reactor 1 includes a vertical cylindrical column 1a having a closed bottom and an open top of a separator 1b having a diameter larger than the diameter of column 1a and mounted to column 1a. The lower edge of the separator is held in close contact with the outer surface of the upper wall of the column, forming a closed inner space in the reactor and outlining an annular cavity 31 between the outer surface of the upper wall of the column and the inner surface of the lower part of the separator. In the column, a solid / liquid mixture is formed from particles of a rhodium-containing solid catalyst suspended in a liquid reaction composition containing methanol, which is a reaction raw material, methyl iodide, which is a promoter, an organic solvent is acetic acid and / or methyl acetate and a small amount of water (2- 10 wt.%). Next, the gas / liquid interaction operation in the bubble column is carried out in the form of blowing gaseous carbon monoxide into a solid / liquid mixture from the bottom of the column. Thus, the synthesis of acetic acid by carbonylation of methanol continues in the reactor at the reaction temperature and reaction pressure between 170 and 190 ° C and between 3.5 and 4.5 MPa, respectively. At the bottom of the column is a liquid inlet 33 for introducing a liquid reaction composition in addition to a gas inlet 32 for blowing carbon monoxide gas so that the liquid reaction composition is continuously introduced and forms an upward flow of solid / liquid mixture in the column. Further, as a result, an upward flow of the mixture is formed, which contains three phases - gas / liquid / solid phase, to obtain acetic acid, while bubbles of gaseous carbon monoxide are forced to rise in the upward flow of the mixture and connect with it. When the ascending stream in the column, which contains three phases, enters the separator, the particles of the solid catalyst and the bubbles of gaseous carbon monoxide are separated from the liquid reaction composition. This will be described in detail below. From the upward flow in the column, which contains three phases - gas / liquid / solid phase, solid catalyst particles are discharged from the upper end of the column and circulated back to the lower part of the column using cavity 31 and external circulation line 34. On the other hand, the liquid reaction the composition and bubbles are separated from the solid catalyst particles at the top of the column, the liquid reaction composition flows through the liquid outlet 35 located in the upper part of the side wall of the separator. The separation wall 36, having a diameter larger than the diameter of the column and smaller than the diameter of the separator, is located in the separator to prevent solid catalyst particles separated from the liquid reaction composition from merging through the liquid product outlet. Because the liquid reaction composition forms a free surface in the separator, the bubbles contained in the liquid reaction composition are separated from the latter, forming the region of the gas phase above the free surface, and eventually escape through the gas outlet 37 located in the upper part of the separator (first separation stage). In addition, a baffle 38 is located opposite the open upper end of the column in the separator so as to prevent droplets of the liquid reaction composition from entering the gas outlet together with bubble gas separated from the liquid reaction composition and exiting through the gas outlet. A cooling device 39 is located in the middle of the external circulation line 34 to remove the heat generated by the reaction and to maintain the internal temperature in the reactor at a constant level.

The liquid reaction composition, which flows through the outlet for the liquid 35 of the reactor, reaches the evaporator column 2, the external pressure of which is substantially maintained at atmospheric pressure through the lower inlet 41 of the evaporator column, and is separated into an exhaust gas and a light liquid fraction which flows through the upper outlet of the column 42, a crude fraction of acetic acid that flows through the middle outlet of the column 43, and a circulation fraction that flows through the lower outlet one hole of the column 44 (second separation stage). The flue gas contains carbon monoxide, which dissolves in the liquid reaction composition, converting methyl iodide to the gas phase, while the liquid light fraction mainly contains methyl acetate, acetic acid and water. If necessary, excess water is separated from the light liquid fraction using an oil / water separator (not shown). Subsequently, part of the light liquid fraction is fed downstream to distillation system 3, while the remaining part of the light liquid fraction is returned to reactor 1. At the same time, the crude acetic acid fraction contains water, methyl iodide, propionic acid and other reaction by-products in addition to acetic acid, all of them are mainly fed downstream to the distillation system 3. The circulation fraction contains nitrogen compounds, a rhodium complex and so on, which are separated from the solid catalyst particles and in addition Acetic acid, methyl acetate, methyl iodide, water and methanol are returned to reactor 1, although part of the circulated fraction can be bypassed through a nitrogen extraction column (not shown) in order to remove nitrogen compounds. The remainder of the light liquid fraction and the crude acetic acid fraction are fed into the distillation system 3, divided into the exhaust gas, the product of the acetic acid fraction, the heavy fraction, which is burned using the incinerator 4 (and contains propionic acid and other reaction by-products) and a circulation fraction (mainly containing acetic acid, water and methanol) that are returned to reactor 1 (third separation stage).

The waste gas is removed from the reactor 1, the evaporation column 2 and the distillation system 3. Since such exhaust gas contains gasified methyl iodide and an organic solvent in addition to unreacted carbon monoxide, useful substances are collected in absorption columns 5 and 6, and the remaining substances are burned in an incinerator 4. Since the exhaust gas leaving the reactor 1 increases the pressure, it is processed in a high-pressure absorption column 5, inside which a pressure of 3 to 5 MPa is created (first absorption stage). On the other hand, the offgas escaping from the evaporator column 2 and the distillation system 3 essentially shows atmospheric pressure so that it is processed in a low pressure (atmospheric pressure) absorption column 6 (second absorption stage). Using a high pressure absorption column and a low pressure absorption column in parallel, all of the feed methanol can be effectively used as an absorbent to absorb the beneficial substances contained in the exhaust gas. While the off-gas that is processed in the high pressure absorption column 5 can be further processed in the low pressure absorption column 6, the cost of assembly and installation when such an arrangement is used must be taken into account.

Figure 4 is a schematic diagram of another structural embodiment of the method for producing acetic acid according to the invention. The arrangement in Fig. 4 differs from the arrangement in Fig. 3, in which the liquid reaction composition flowing out from the reactor 1 enters the evaporation tank 8 through the inlet 81, where a single evaporation takes place instead of a single distillation. More specifically, the liquid reaction composition is vaporized into an evaporation tank under reduced pressure and is separated into a gas fraction and a liquid fraction from the remaining liquid (second separation stage). The gas fraction contains carbon monoxide, which does not react, but dissolves in the liquid reaction composition, and methyl iodide, as well as crude acetic acid, which must be purified to obtain acetic acid in the subsequent distillation step, and part of the organic solvent, and by-products that flow through the upper outlet 82 of the evaporation tank and enter the distillation system 3. Therefore, the non-exhausted gas is released from the evaporation tank 8. On the other hand, liquid the fraction contains an organic solvent, heavy substances and nitrogen compounds flowing out from the solid catalyst particles, which flows through the lower outlet 83 of the evaporation tank and returns to the reactor 1. In other cases, the arrangement in FIG. 4 is similar to that in FIG. 3.

Raw methanol is used as an absorbing liquid in absorption columns 5 and 6. Using raw methanol makes the usual diffusion step superfluous and methanol, which is used as an absorbing liquid, can be sent to the reaction column without treatment. The temperature of methanol, which is used in the absorption columns 5 and 6, is regulated from 10 to 25 ° C (usually cooled by a cooling device 7) to improve the efficiency of absorption of beneficial substances contained in the exhaust gas. Absorption efficiency decreases when the temperature of methanol exceeds 25 ° C. For example, in the absorption and removal of methyl iodide from the off-gas, losses typically exceed 0.1% when the temperature exceeds 25 ° C. On the other hand, when the temperature of methanol is lower than 10 ° C, the temperature of the lubricating-cooling emulsion is also forced to decrease to an uneconomical increase in the cost of the process.

The methanol used as the absorbing liquid is distributed in the high pressure column 5 and in the low pressure column 6. The losses of methyl iodide and methanol that flows from the system can be minimized when 50-80%, and more preferably 55-70% of the total methanol, which flows through the absorption columns is distributed in the low pressure column (distribution coefficient of the low pressure column). Because the ratio of the exhaust gas flow rate from the reactor 1 to the exhaust gas flow rate from the evaporator column 2 and the distillation system 3 is approximately between 1.5: 1 and 1: 1.5, the ratio of the absorbing liquid flow rate to the exhaust gas flow rate is between 1 / 1.0 and 1 / 0.25 in the high pressure absorption column and between 1 / 0.2 and 1 / 0.4 in the low pressure absorption column.

In the case of methanol carbonylation by the heterogeneous catalysis reaction taking place in reactor 1, since acetic acid, which is a reaction product and / or methyl acetate, which is a by-product of the reaction, are used as solvents, the solubility of the catalyst, which is the rhodium complex, does not create problems as in the case of homogeneous catalysis. In other words, there is no need for the presence of a significant amount of water. It is usually necessary that the water contains only 2-10 wt.%. On the other hand, a rhodium complex supported on insoluble particles of a resin containing a pyridine ring in the molecular structure is used as a metal catalyst. More specifically, a catalyst can be used in which the rhodium complex [Rh (CO) ₂ I ₂ ] ^- is deposited by ion exchange on a pyridine resin, the pyridine portion of which is converted to a quaternary ammonium salt using an alkyl iodide. However, when the process for producing acetic acid has been carried out for a long time, a problem may arise in that the pyridine backbone of the pyridine resin, which is converted to a quaternary ammonium salt, can be partially released from the resin and dissolved in the liquid phase. The carbonyl complex of rhodium can then accompany the pyridine skeleton (nitrogen-containing compound), which is released from the resin and becomes the contents of the liquid reaction mixture. The carbonyl complex of rhodium trapped in the liquid reaction mixture is precipitated in an evaporation column (evaporation tank) as a result of a decrease in pressure and condensation. Therefore, the circulation fraction from the evaporation column, which is recycled to the reactor, should preferably be partially discharged to the nitrogen removal column in order to avoid the accumulation of nitrogen-containing compounds in the liquid reaction mixture. Regarding the type of reactor, the bubble column shown in FIGS. 3 and 4 is preferred. For a conventional stirred tank reactor, the problem is that the resin particles that serve as supports for the solid metal catalyst can easily break. Further, it is not easy to separate the solid catalyst particles from the liquid reaction mixture, unlike the bubble column reactor. From this point of view, in the case of a bubble column reactor, the solid catalyst particles can easily be separated from the liquid reaction mixture if the liquid is removed from the aforementioned catalyst particle layer (which is created due to the upward flow in the reactor), therefore, the solid catalyst particles are less susceptible to mechanical shock and, therefore, the resin particles are almost not destroyed. In the bubble column reactor shown in FIG. 3, which is adapted to circulate solid catalyst particles, the resin layer rises above the upper portion of the traction section, while the upper surface of the resin layer does not form, and the solid catalyst particles roll off from the upper portion of the traction section without further growth and, consequently, the upper surface of the resin layer is formed there, since the diameter of the reactor increases sharply in the separator in order to reduce the rate of upward fluid flow. As a result, the solid catalyst particles are separated from the liquid reaction mixture.

In the bubble column reactor, the concentration of suspended solid catalyst particles must be kept lower than in the stirred reactor in order to uniformly disperse the solid catalyst particles in the liquid reaction mixture. Therefore, it has disadvantages, for example, the reaction rate is limited. However, in the bubble column reactor shown in FIG. 3, which is adapted to circulate solid catalyst particles, the solid catalyst particles are forced to circulate from top to bottom in the column using an external circulation loop, so that the solid catalyst particles can very effectively contact the liquid reaction mixture even when the concentration of suspended particles of the solid catalyst is increased. Because carbon monoxide gas is blown through the traction section, there is an internal difference in density between the inner traction section and the external circulation line, so that there is a flow of free circulating particles of solid catalyst. The circulation will be highly uniform when the profile and position of the hole for injecting carbon monoxide and the profile and position of the hole for injecting liquid reaction mixture are approximately located in order to support the movement of solid catalyst particles in the lower portion of the traction section.

Now the present invention will be described further using examples (example 1, 2 and comparative examples 1-3).

In each example, acetic acid was obtained experimentally using an experimental bubble column reactor with an external circulation system, as shown in Fig. 1 (height - 15 m, internal diameter of the reactor - 150 mm). After filling the reactor with a predetermined amount of catalyst (vinylpyridine ion exchange resin bearing a rhodium catalyst, 0.85 wt.% Rhodium relative to the resin, density 1.2, average particle size 0.45 mm), the traction section 12 was filled with acetic acid using a pipe, injecting fluid. Therefore, CO is injected so as to force it to flow upward from the bottom of the traction portion 12 at a predetermined flow rate to cause the onset of circulation of acetic acid and catalyst, and at the same time, part of the acetic acid is discharged by introducing CO from the separator section 13 by pipe systems. Excess gaseous CO is removed through the top of the separator section 13. The internal pressure in the reactor was maintained at a predetermined level using a control valve, and the temperature inside the cylindrical reactor was raised to a predetermined level using a heater, while acetic acid and a solid catalyst were induced to circulation. Then, the reaction feeds were introduced using the pipe system at a constant rate and the discharged reaction liquid was removed from the separator section 13 using the pipe system.

In each of the examples, the experiment was carried out following the above procedure under the conditions listed in Table 1. The Kla value was observed and the total reaction productivity (rate of production of acetic acid per unit volume of reaction volume kmol / h / m ³ ) achieved in the experiments was compared. The performance achieved in experiment 1 was used as a reference (score 10) and the achievements in various examples were evaluated on a relative basis. Table 1 also shows the results.

Table 1 The concentration of solid catalyst (kg / m ³ ) CO partial pressure
(MPa) Volumetric flow
With
(%) Reduced fluid velocity
(m / s) Example 1 280 1.8 7 0.30 Example 2 280 1.8 fifteen 0.40 Compare approx. 1 280 1.8 2 0.25 Compare approx. 2 280 0.9 5 0.20 Compare approx. 3 90 1.8 5 0.15

(continued)

Kla value (1 / hour) The total reaction rate (acetic acid kmol / h) / m ³ Example 1 1000-5000 10 Example 2 1500-5500 12 Compare approx. 1 300-4500 7 Compare approx. 2 500-4500 3 Compare approx. 3 500-4500 3

(Example 3)

Acetic acid was obtained using an experimental bubble column reactor with an external circulation system, as shown in FIG. 2 (height — 15 m, internal diameter of the reactor — 150 m). A pre-calculated amount of catalyst (vinylpyridine ion exchange resin bearing a rhodium catalyst, 0.85 wt.% Rhodium, relative to the resin, density 1.2, average particle size 0.45 mm) was loaded into the reactor 21 in order to make the concentration of solid catalyst on unit reaction volume equal to 135 kg / m ³ . Acetic acid was then poured into the traction section 22 through a fluid injection tube, and then carbon monoxide (CO) was injected through the carbon monoxide injection hole so as to direct the flow upward as a jet stream with a pre-calculated flow rate to induce acetic acid circulation and catalyst. At the same time, part of the acetic acid that spills out due to the introduction of CO is discharged from the separator section 23 using a pipe system. Excess CO gas is discharged through the top of the separator section 23. The internal pressure in the reactor is maintained at a predetermined level by means of a control valve and the internal temperature of the cylindrical reactor is raised to a predetermined level by means of a heater, while acetic acid and the solid catalyst induce circulation. Then, the reaction feed is introduced into the reactor using a pipe system at a constant rate, and the poured reaction liquid is withdrawn from the separator section 23 using a pipe system.

The first level carbon monoxide injection hole is located on the upper part of the narrowed section and the second level carbon monoxide injection hole is located below the first level carbon monoxide injection hole and near the connection of the narrowed section and the circulation line located in the lower part of the narrowed section. The branched pipeline of the gas distributor is suitable for blowing holes. CO gas is introduced at a flow rate of 340 NL / min from the first stage carbon monoxide injection port and at a flow rate of 86 NL / min from the second stage carbon monoxide injection port. The reaction proceeded stably when acetic acid was produced under the above conditions.

(Comparative example 4)

Acetic acid was obtained as in Example 3, except that one hole from the branched pipe of the gas distributor was placed on the top of the narrowed section and gaseous CO was introduced at a flow rate of 340 NL / min. As a result, the volume of the circulating substance gradually decreased due to the deposition of the solid catalyst, and, therefore, the reaction proceeded unstably. At the same time, gas accumulates under the solid in the liquid drop zone as a result of the short path, so that the occurrence of circulation takes a long time.

(Example 4)

Acetic acid was synthetically synthesized by methanol carbonylation using the flow chart shown in FIG. Acetic acid and methyl iodide were placed in reactor 1, respectively 10 kg and 2 kg, and the pyridine resin, which was converted into a quaternary ammonium salt, and the rhodium carbonyl complex [Rh (CO) ₂ I ₂ ] ^were added to the reactor to prepare a solid catalyst containing rhodium. Subsequently, methanol was supplied through a liquid inlet 33 using absorption columns 5 and 6 at a rate of 5.3 kg / min, while carbon monoxide was supplied through a gas inlet at a speed of 4.2 l / min. The liquid reaction mixture that flowed out from reactor 1 was continuously cleaned in the evaporation column 2 and distillation column 3 to obtain the final product of acetic acid, and the circulating fraction that flowed from the two columns was returned to the liquid inlet of the reactor 1. Table 2 shows operating conditions of the reactor 1, the evaporation column 2 and the distillation column 3. The exhaust gas from the reactor 1 was forced to pass through the absorption column at high pressure 5, while the exhaust gas from the evaporation column 2 and the column Distillation 3 was passed through the absorption column at low pressure 6, before being burned together with the heavy fraction from the distillation column 3 in the combustion furnace 4. After the operation became stable, the temperature of methanol, which was used as the liquid absorbent, was the distribution coefficient of the absorption column at low pressure varied. Then, the ratio between the collected methyl iodide and the loss of methanol and carbon monoxide was observed by measuring the flow rate using a flow meter and analyzing the composition using gas chromatography. The results are shown in table 3.

table 2 Temperature,
° C Pressure
MPa Flow rate
kg / h Reactor Inside 180 4.0 Flue gas 0.78 Evaporation column Column bottom 141 0.27 Receiving tank 46 0.20 Flue gas 0.75 Distillation column Column bottom 148 0.24 Receiving tank fifty 0.24 Flue gas 0.01 Table 3 Absorbent liquid Pace.,
° C Distribution coefficient Expiration rate
(%) CH ₃ I Absor fluid With Methanol twenty 60 0,07 0.5 90 Methanol twenty fifty 0.50 0.6 90 Methanol twenty 80 0.10 0.5 91 Methanol twenty 40 1,50 0.7 90 Methanol twenty 90 1.00 0.7 92 Methanol 25 60 0.08 0.5 90 Methanol 10 60 0.06 0.5 90 Methanol 40 60 0.30 0.6 91 Acetic acid 25 60 0.05 0.2 92

Claims (24)

1. The method of producing acetic acid by carbonylation of methanol with carbon monoxide (CO) by carrying out a heterogeneous catalysis reaction in a bubble column reactor with fluidization of a heterogeneous catalyst equipped with an external circulation circuit, characterized in that the carbonylation reaction is carried out at a concentration of solid catalyst of not less than 100 kg / m ³ based on the volume of the reaction system, said catalyst is formed by a carrier - vinylpyridine resin, coated with rhodium complex in which the partial pressure of carbon monoxide in the reactor is between 1.0 and 2.5 MPa and the degree of exhaustion of carbon monoxide is between 3 and 15% of the theoretical reaction volume of carbon monoxide, while the reduced liquid velocity is between 0.2 and 1.0 m / s. 2. The method according to claim 1, in which the partial pressure of carbon monoxide in the reactor is maintained between 1.7 and 2.2 MPa. 3. The method according to claim 1, in which the degree of exhaustion of carbon monoxide is between 5 and 10% of the theoretical reaction volume. 4. The method according to claim 1, in which methyl iodide is used as a promoter. 5. The method according to any one of claims 1 to 3, in which acetic acid and methyl acetate are used as a solvent. 6. The method according to any one of claims 1 to 3, in which the concentration of water in the reactor is between 2 and 10 wt.%. 7. The method according to any one of claims 1 to 3, in which the ratio of the length L to the diameter D of the bubble column reactor or L / D is not less than 8. 8. The method according to any one of claims 1 to 3, in which the bubble column reactor has an external circulation line and a heat exchanger integrated in the circulation line. 9. The method according to any one of claims 1 to 3, in which the liquid reaction product is taken from the reaction liquid containing a solid catalyst, using a separator located in the upper part of the column, and fed to the evaporation column and a light fraction containing mainly acetic acid and the heavy fraction are extracted respectively from the upper section, the middle section and the lower section of the evaporation column and are separated from each other. 10. The method according to claim 9, in which at least part of the heavy fraction is processed using a device for removing nitrogen-containing compounds and fed to the reverse circulation in a bubble column reactor. 11. The method according to claim 1, in which carbon monoxide is injected into the reactor through the holes for the injection of carbon monoxide, located at least two levels. 12. The method according to claim 11, in which carbon monoxide is injected into the reactor through the holes for the injection of carbon monoxide, located at two levels. 13. The method according to claim 11, in which said bubble column reactor has an external circulation line, and said carbon monoxide injection holes located at least at two levels, include at least carbon monoxide injection hole located at a level required for fluidization in the reactor, and a hole for the injection of carbon monoxide, located at a different level to create the mobility of the solid catalyst in the lower part of the reactor, selection or fluidization in the external circulation line. 14. The method according to item 13, in which the bubble column reactor has a narrowed section in the lower part of the cylindrical reactor with an inner diameter ranging from 30 to 70% of the remaining part of the cylindrical reactor and a hole for the injection of carbon monoxide is located in the upper part of the narrowed section for fluidization solid catalyst, while another hole for the injection of carbon monoxide is located near the connection of the reactor and the external circulation line (input of the circulation section) located at the bottom of the narrowed section for creating mobility of the solid catalyst; and selecting or fluidizing the solid catalyst in the external circulation line. 15. The method according to any one of claims 11-14, in which the holes for the injection of carbon monoxide are branched by tubular gas distributors. 16. The method according to any one of claims 1 to 3, in which the separator is located at the top of the reactor for collecting unreacted gaseous CO, which is taken from the reaction liquid containing unreacted gaseous CO, and a solid catalyst, and removing a liquid reaction product that does not contain a solid catalyst. 17. A bubble column cylindrical reactor column for producing acetic acid by carbonylation of methanol with carbon monoxide by a heterogeneous catalysis reaction, for which the ratio of the column height to its diameter is not less than 8, equipped with an external liquid and solid phase circulation line in the reaction mass, with a closed bottom and an open top a part equipped with a separator whose diameter is larger than the diameter of the column and which includes a reflective baffle for separating particles of the solid phase and gas from the liquid, as well as it has a narrowed section in its lower part with an inner diameter ranging from 30 to 70% of the remaining part of the cylindrical reactor, characterized in that it has openings for the injection of carbon monoxide, located at least two levels. 18. A bubble column cylindrical reactor column according to claim 17, characterized in that the hole for injecting carbon monoxide is located in the upper part of the narrowed section for fluidizing the solid catalyst, while another hole for injecting carbon monoxide is located near the connection of the reactor and the external circulation line ( the input of the circulation section) located at the bottom of the narrowed section to create the mobility of the solid catalyst and the selection or fluidization of the solid catalyst in the external circulation line. 19. A method of producing acetic acid by carbonylation of methanol with carbon monoxide in the presence of a solid metal catalyst, characterized in that it includes a reaction step leading to a carbonylation reaction taking place in a pressurized bubble column reactor by suspending a solid metal catalyst in a liquid reaction mixture containing an organic solvent composed of methanol, methyl iodide, acetic acid and / or methyl acetate and a small amount of water and blown carbon monoxide gas into a liquid reaction mixture with a concentration of solid catalyst of not less than 100 kg / m ³ in terms of the volume of the reaction system; a first separation step for separating and withdrawing the liquid reaction mixture and the off-gas from the above reaction; the second separation stage of conducting instant distillation by introducing the liquid reaction mixture separated in the first separation stage into the evaporation column, while separating the exhaust gas and the light liquid fraction flowing from the upper section of the column and the crude fraction of acetic acid flowing from the middle section of the column, and a circulation fraction flowing from the bottom of the column; a third separation stage introducing a portion of the light liquid fraction and the crude acetic acid fraction separated in the aforementioned second separation stage into a distillation system, while separating the exhaust gas, the product of the acetic acid fraction, the heavy fraction and the circulation fraction; a circulation step of returning to the reactor a separated light liquid fraction and a circulation fraction separated in the aforementioned second separation stage and a circulation fraction separated in the aforementioned third separation stage; a first absorption step for conducting gas absorption for the exhaust gas separated in the first aforementioned separation step using methanol as an absorbent liquid; a second absorption stage for conducting gas absorption for the exhaust gas separated in the aforementioned second separation stage and the exhaust gas separated in the aforementioned third separation stage using methanol as an absorbing liquid at a pressure lower than in the aforementioned first absorption stage; a step of exhausting exhaust gases leaving the system after the aforementioned first absorption stage, exhaust gases leaving after the aforementioned second absorption stage, and a heavy fraction separated in the aforementioned third stage; that methanol which stabilizes at a temperature of from 10 to 25 ° C. is used as an absorbing liquid in the aforementioned first and second absorption stages and separated to use 50-80 wt.% of all methanol used in the two absorption stages in the aforementioned second absorption stage, and methanol, leaving after two absorption stages, is used as raw material methanol in the reaction stage. 20. A method of producing acetic acid by carbonylation of methanol with carbon monoxide in the presence of a solid metal catalyst, characterized in that it includes a reaction step leading to a carbonylation reaction taking place in a pressurized bubble column reactor by suspending a solid metal catalyst in a liquid reaction mixture containing an organic solvent composed of methanol, methyl iodide, acetic acid and / or methyl acetate and a small amount of water and a purged gas carbon monoxide in a liquid reaction mixture with a concentration of solid catalyst of not less than 100 kg / m ³ in terms of the volume of the reaction system; a first separation step for separating and discharging the liquid reaction mixture and off-gas from the aforementioned reaction stage; a second separation step for conducting instant distillation by introducing a liquid reaction mixture separated in the first separation step into an evaporation tank, while separating the gas fraction flowing from the upper section of the column and the light fraction flowing from the lower section of the column; the third separation stage of the initial gas fraction separated in the aforementioned second separation stage in the distillation system and the separation of the exhaust gas, the product of the acetic acid fraction, the heavy fraction and the circulation fraction; a circulation step of returning to the reactor a separated light liquid fraction separated in the aforementioned second separation stage and a circulation fraction separated in the aforementioned third separation stage; a first absorption step for conducting gas absorption for the off-gas separated in the aforementioned first separation step using methanol as an absorbent liquid; a second absorption stage for conducting gas absorption for the exhaust gas separated in the aforementioned third separation stage using methanol as an absorbing liquid at a pressure lower than in the aforementioned first absorption stage; a step of exhausting exhaust effluent gases leaving the system after the aforementioned first absorption stage, exhaust gases discharging after the aforementioned second absorption step, and a heavy fraction separated in the above third stage; that methanol, which stabilizes at a temperature of 10 to 25 ° C., is used as an absorbing liquid in the aforementioned first and second absorption stages and is separated to use 50-80 wt.% of all methanol used in the two absorption stages in the aforementioned second absorption stage, and methanol, leaving after two absorption stages, is used as raw material methanol in the reaction stage. 21. The method according to claim 19 or 20, in which the solid catalyst is formed by applying to the quaternary ammonium pyridine resin a carbonyl complex of rhodium. 22. The method according to claim 19 or 20, in which the methanol is separated to use 55-70 wt.% Incoming methanol for use in two absorption stages in the aforementioned second absorption stage. Priority on points and signs: 03/13/2003 - claims 1-10 and the sign of claim 20 "with a concentration of solid catalyst of not less than 100 kg / m ³ in terms of the volume of the reaction system"; 03/31/2003 - claims 11-22 with the exception of the aforementioned feature from paragraph 20.

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