The method of obtaining acetic acid by carbonylation

 

(57) Abstract:

Acetic acid is obtained by carbonyliron methanol and/or its reactive derivative in the liquid phase in the presence of iridium carbonylation catalyst, methyliodide of socializaton and promoter, and in the liquid reaction mixture maintain a water content of not more than 6.5 wt.% water, the concentration of acetate in the range 1-35 wt.% concentration under the conditions within 4-20 wt.%. The promoter chosen from the group consisting of ruthenium, osmium, rhenium, cadmium, mercury, zinc, gallium, indium, tungsten. The molar ratio of promoter : iridium equal to (0.5 to 15) : 1. Preferably the concentration of the iridium catalyst 400-3000 ppm, and the concentration of ruthenium promoter - 400-4000 ppm. As a result of application of an improved catalyst increases the reaction rate and the yield of acetic acid. 11 C.p. f-crystals, 11 tab., 8 Il.

The present invention relates to a method for producing acetic acid, in particular to a method for producing acetic acid by carbonyliron in the presence of an iridium catalyst and methyliodide of socializaton.

Obtaining carboxylic acids by means catalyzed by iridium carbonylation known and OPI, 0618183 and 0657386.

In the United Kingdom patents 1234121, USA 3772380 and Germany 1767150 describes how catalyzed by iridium carbonylation, the implementation of which is not used promoters as provided by the present invention.

In the European patent 0618184 describes how carbonylation with obtaining carboxylic acids and/or their esters in the presence of iridium catalyst. The reaction mixture is characterized as containing from 0 (not including) up to 10% water, from 0 (not including) 10% of halogenated socializaton, 2-40% of ester and carboxylic acid as the solvent. In the European patent 0618184 not described the use of the promoter.

In the European patent 0618183 describes how carbonylation with obtaining carboxylic acids, for example acetic acid, in the presence of iridium and rhodium compounds.

In the European patent 0657386 describes a method for the solution of the iridium catalyst and its use in the carbonylation reaction with obtaining acetic acid.

In the European patent 0643034 describes how carbonylation of methanol and/or its reactive derivative in the presence of acetic acid, the iridium catalyst, under the conditions, water hence xperiment with batch and continuous processes. In the experiments with continuous processes, the concentration of water is only 6.8 wt.%.

Therefore, there remains a need in the development of an improved method catalyzed by iridium carbonylation.

Thus, in accordance with the present invention offers a method of obtaining acetic acid, comprising (1) a continuous feed of methanol and/or its reactive derivative and carbon monoxide in a carbonylation reactor for, which contains the liquid reaction mixture comprising iridium carbonylation catalyst, methyliodide socialization, water in limited concentrations, acetic acid, methyl acetate and at least one promoter; (2) the introduction of methanol and/or its reactive derivative in contact with carbon monoxide in a liquid reaction mixture with obtaining acetic acid and (3) allocation of acetic acid from the liquid reaction mixture, characterized in that during the reaction in the liquid reaction mixture is continuously support (a) the water concentration is not more than 6.5 weight. %, (b) the concentration of acetate in the range 1-35 wt.% and (C) concentration under the conditions within 4-20 wt.%.

The present image is idcol reaction medium, includes concentrations in some water, methyliodide and acetate. This provides several technical advantages.

Thus, in accordance with the present invention the reaction rate of the carbonylation increases with decreasing concentration of water in the liquid reaction mixture from level greater than 6.5 wt.%, passes through a maximum when the concentration of water is not more than 6.5 wt.% and then decreases as it approaches the water concentration to very low values. Consequently, the rate of carbonylation reaction in the method according to the present invention is generally greater than that achieved when the concentration of water in excess of 6.5 wt.% (under other equal parameters, excluding fluctuations in the concentration of water, which can be compensated by varying the concentration of acetic acid). The water concentration at which the rate of carbonylation is maximum with increasing concentration of methyl acetate in the liquid reaction mixture increases. I believe that the water concentration at which the rate of carbonylation is a maximum with increasing concentration under the conditions in the liquid reaction mixture is reduced.

In addition, it was found that the accelerating effect of the promoter in matched with the invention increases. As noted below, it was found that the maximum rate of carbonylation in the relationship between the rate of carbonylation and water concentration of the positive effect of the promoter in accordance with the present invention, such as ruthenium, is the greatest. That is, it was found that the positive effect of the promoter in accordance with the present invention, such as ruthenium, is greatest when the concentration of water, which provides the maximum rate of carbonylation under any given concentrations of acetate and under the conditions. In the process according to the invention the concentration of water does not exceed 6.5 wt.%.

Moreover, in the method according to the present invention the process when the water concentration is not more than 6.5 wt.% you can simplify the allocation of acetic acid from the reaction mixture withdrawn from the reactor for carbonylation, reducing the amount of water that must be separated from acetic acid; separating water from the acetic acid is part of the allocation process associated with intensive energy consumption, therefore reducing the concentration of water leads to simplification of the process and/or sizebritney may provide process at low concentrations of the iridium catalyst while maintaining the rate of carbonylation. The advantage of this is to reduce the rate of formation of by-products such as propionic acid.

Water can be formed in situ in the liquid reaction mixture, for example, due to the esterification reaction between methanol reagent and the resulting acetic acid. A small amount of water may be released through hydrogenation of methanol to form methane and water. Water can be introduced into the carbonylation reactor for in conjunction with other components of the liquid reaction mixture or separately. Water can be separated from other components of the reaction mixture withdrawn from the reactor, and can be returned to the cycle in controlled amounts to maintain the desired concentration of water in the liquid reaction mixture. The concentration of water in the liquid reaction mixture does not exceed about 6.5 wt.%, that is, it is less than or equal to 6.5 wt.%, preferably not more than 6 wt.%. The preferred water concentration is at least 0.1 wt.%, more preferably at least 1 wt.%.

In the method according to the present invention is suitable reactive derivatives of methanol include methyl acetate, dimethyl ether and methyliodide. As reagents in the method according to the invention can be ispaat methanol and/or methyl acetate. At least some amount of methanol and/or reactive derivative due to the response obtained with acetic acid or solvent is converted into acetate, which is therefore contained in the liquid reaction mixture. In the method according to the present invention, the preferred concentration of methyl acetate in the liquid reaction mixture is 1-30 wt.%, more preferably 5 to 25 weight. %. It was found that with increasing concentration of acetate reaction rate of carbonylation increases, and the selectivity for products such as propionic acid and carbon dioxide decreases. However, with increasing concentration of methyl acetate quantity, which must be returned to the reactor for carbonylation from the stage of selection of acetic acid increases. In addition, excessively high concentrations of acetate may have a negative influence on the phase separation of the aqueous and methyliodide phases at the stage of selection of acetic acid. Moreover, an excessively high concentration of acetate may have undesirable influence on the reaction rate of the carbonylation by reducing the partial pressure of carbon monoxide at about the preferred concentration methyliodide of socializaton in the liquid reaction mixture is 5-16 weight. %. With increasing concentration of methyliodide of socializaton the rate of formation of by-products such as propionic acid, carbon dioxide and methane decreases. The increase in the rate of carbonylation, due to the increased concentration under the conditions, at low water concentrations greater than at higher water concentrations. Moreover, with increasing concentration under the conditions it is possible to simplify the phase separation of the aqueous and methyliodide phases at the stage of selection of acetic acid. However, increasing the concentration under the conditions at a certain total pressure in the reactor for carbonylation can cause an undesirable reduction in the partial pressure of carbon monoxide.

According to a preferred variant implementation of the method according to the present invention, the concentration of iridium carbonylation catalyst in the liquid reaction mixture is 400-5000 ppm in terms of iridium, more preferably 500-3000 ppm in terms of iridium and most preferably 700-3000 ppm in terms of iridium. In the method according to the present invention with increasing concentrations of iridium reaction rate of carbonylation increases.

Iridium catalyst in Zhidkin mixture. The iridium catalyst can be added to the liquid reaction mixture for the reaction of carbonyl in any acceptable form, in which it dissolves in the liquid reaction mixture or can pass into the soluble form. Examples of acceptable iridectomies compounds that can be added to the liquid reaction mixture, include IrCl3, IrI3, IrBr3, [Ir(CO)2I]2, [Ir(CO)2Cl]2, [Ir(CO)2Br]2, [Ir(CO)2I2]-H+, [Ir(CO)2Br2]-H+, [Ir(CO)2I4]-H+,

[Ir(CH3)I3(CO)2]-H+Ir4(CO)12, IrCl33H2O, IrBr33H2O Ir4(CO)12, iridium metal, Ir2O3, IrO2, Ir(acac)(CO)2, Ir(acac)3acetate iridium [Ir3O(OAc)6(H2O)3] [OAc] and hexachloroiridium acid [H2IrCl6] preferably does not contain chloride complexes of iridium such as acetates, oxalates and acetoacetates, which are soluble in one or more components of the reaction mixture for carbonylation, such as water, alcohol and/or carboxylic acid. Especially preferred raw iridium acetate, which can be used in acetic kiloo least one promoter. Suitable promoters are preferably selected from the group comprising ruthenium, osmium, rhenium, cadmium, mercury, zinc, gallium, indium and tungsten, the preferred ruthenium and osmium and most preferred ruthenium. In a preferred embodiment, the promoter contained in an effective amount up to the limit of its solubility in the liquid reaction mixture and/or any liquid process streams returned to the carbonylation reactor for from the stage of selection of acetic acid. Acceptable content promoter in the liquid reaction mixture corresponds to a molar ratio of promoter and iridium (0,5-15):1. As noted above, it was found that the positive effect of promoter such as ruthenium, is greatest when the concentration of water, which provides the maximum rate of carbonylation in any preselected concentration of acetate and under the conditions. The corresponding concentration of the promoter is 400-5000 parts/million

The promoter can be any suitable promoter metallsoderjasimi compound which is soluble in the liquid reaction mixture. Such a promoter can be added to the liquid reaction mixture for the reaction of carbonyl in l is storemay form. Examples of acceptable ruteniysoderzhaschim compounds that can be used as sources of promoter include chloride, ruthenium (III) chloride trihydrate ruthenium (III) chloride, ruthenium (IV) bromide, ruthenium (III), ruthenium metal, the oxides of ruthenium formate, ruthenium(111), [Ru(CO)3I3]-H+, [Ru(CO)2I2]n, [Ru(CO)4I2], [Ru(CO)3I2I2, Tetra(Aceto)chloroethene (II, III) acetate, ruthenium (III) propionate, ruthenium (III) butyrate ruthenium (III), PENTACARBONYL ruthenium, tributenetherlands and mixed haloalkanes ruthenium, such as dimer dichlorocarbanilide (II) dimer dibromodicyanobutane (II), and other romanialaisia complexes, such as tetrachlorobis(4-Zimen)tirutani (II), tetrachlorobis(benzene)tirutani (II), dichloro(cycloocta-1,5-diene) ruthenium (II) polymer and Tris(acetylacetonate)ruthenium (III).

Examples of suitable oslistarray compounds which can be used as sources of promoter include the hydrate and the anhydrous chloride of osmium (III), osmium metal, osmium tetroxide, trioctyldodecyl, [Os(CO)4I2] , [Os(CO)3I2]2, [Os(CO)3I3]-H+, pentachlor- - nitrotoluene and smiling is XY.

Examples of suitable registergui compounds which can be used as sources of promoter include Re2(CO)10, Re(CO)5Cl, Re(CO)5Br, Re(CO)5I, ReCl3xH2O, [Re(CO)4I]2, [Re(CO)4I2]-H+and ReCl5yH2O.

Examples suitable for use of cadmium-containing compounds include Cd(OAc)2, CdI2, CdBr2, CdCl2Cd(OH)2and cadmium acetylacetonate.

Examples of suitable mercury-containing compounds which can be used as sources of promoter are Hg(OAc)2, HgI2, HgBr2, HgCl2Hg2I2and Hg2Cl2.

Examples of suitable zinc-containing compounds which can be used as sources of promoter, are Zn(OAc)2, Zn(OH)2, ZnI2, ZnBr2, ZnCl2and zinc acetylacetonate.

Examples of suitable geliysoderzhaschih compounds which can be used as sources of promoter include gallium acetylacetonate, gallium acetate, GaCl3, Gabr data member3, GaI2, Ga2Cl4and Ga(OH)3.

Examples of suitable indiadelhi compounds, Cl3, InBr3, InI2, InI and In(OH)3.

Examples of suitable tungsten-containing compounds which can be used as sources of promoter, are W(CO)6, WCl4, WCl6, WBr5WI2C9H12W(CO)3and any chlorine-, bromine - or iodirovannoi connection tungsten.

In a preferred embodiment, iridium - and promotersthe connection free of impurities that form or produce in situ the ionic iodides, can ingibiruet the course of the reaction, for example, salts of alkali, alkaline-earth metals or other metals. The concentration of ionic contaminants, such as (a) the corrosion products of metals, particularly Nickel, iron and chromium, and (b) phosphines or nitrogen-containing compounds or ligands that can quaternization in situ in the liquid reaction mixture should be maintained at a minimum level, because they have an undesirable influence on the course of the reaction, separating into a liquid reaction mixture of the I-that is adversely affecting the reaction rate. Some polluting the corrosion products of metals, such as molybdenum, less sensitive, as installed, to the selection of the I--preferably less than 250 ppm of the I-.

Carbon monoxide as a reactant may be almost pure or may contain inert impurities such as carbon dioxide, methane, nitrogen, noble gases, water and C1-C4paraffin hydrocarbons. The content of hydrogen in the carbon monoxide and released in situ due to the reaction of conversion of water gas is preferably maintained at a low level, as its presence can lead to the formation of hydrogenation products. Thus edocfile less than 0.5 mol.% and most preferably less than 0.3 mol.%, and/or preferred partial pressure of hydrogen in the carbonylation reactor for less than 1 bar, more preferably less than 0.5 bar and most preferably less than 0.3 bar. Acceptable partial pressure of carbon monoxide in the reactor is 1-70 bar, preferably 1-35 bar, more preferably 1-15 bar.

Total acceptable overpressure during the carbonylation reaction is 10-200 bar, preferably 15-100 bar, more preferably 15-50 bar. Acceptable temperature of the carbonylation reaction is in the range of 100-300oC, preferably in the range of 150-220oC.

The method according to the present invention preferably takes place by carrying out a continuous process.

The resulting acetic acid can recover from a liquid reaction mixture removed from the carbonylation reactor for vapor and/or liquid and the release of acetic acid from the outgoing material. Acetic acid is preferable to recover from a liquid reaction mixture by continuous removal of liquid reaction mixture from the reactor for carbonylation and the release of acetic acid from the withdrawn liquid reaction mixture by implementing one or from the other components of the liquid reaction mixture, such as iridium catalyst, methyliodide socialization, promoter, methyl acetate, unreacted methanol, water and acetic acid solvent, which can be returned to the reactor to maintain their concentrations in the liquid reaction mixture. To preserve the stability of the iridium catalyst in the implementation stage of the allocation received acetic acid water concentration in process streams containing iridium carbonylation catalyst returned to the reactor for carbonylation, you should maintain at least 0.5 wt.%.

Especially preferred liquid reaction mixture comprises about 5 wt.% water, about 7 wt.% methyliodide of socializaton, about 15 weight. % acetate, iridium catalyst at a concentration in the range of 400-3000 ppm in terms of iridium, which achieves the rate of the carbonylation reaction in the range of 10-40 mol/l/h at the reaction temperature of the carbonylation approximately 189oC, the excess pressure of the carbonylation reaction 22-30 bar and a partial pressure of carbon monoxide 4-12 bar, ruthenium promoter at a concentration in the range of 400-4000 ppm in terms of ruthenium, which provides the m acetic acid. To achieve a higher or lower speed, you can use a higher or lower concentration of the catalyst and/or a higher or lower temperature and/or higher or lower partial pressure of carbon monoxide.

Further, the invention is illustrated using the following examples, without limiting its scope, with reference to Fig. 1-6, showing the influence of water concentration on the rate of carbonylation in the experiments conducted in the autoclave periodic processes. In Fig. 7 presents a schematic of the setup used to illustrate the method according to the present invention during the continuous process. In Fig. 8 shows the effect of water concentration on the rate of carbonylation reactor continuous action.

Experiments with periodic carbonyliron

To illustrate the essence of the present invention conducted the following experiments with periodic processes. The reaction components were loaded into the autoclave together with so many carbonyliron reagent (methyl acetate), which is completely consumed during the reaction. In the course carbonyliron of acetate and water consumption were equivalent to these parameters when carbonyliron methanol.

Control the speed of the carbonylation reaction and calculate the concentration of the reaction components during experiment allows to determine the rate of the carbonylation reaction, which should be expected in the case of a continuous carbonylation process while maintaining a stable state of the liquid reaction mixture, which is identical to the entire reaction mixture, calculated at any given time during the experiment with periodic process. In experiments with periodic processes, the term "reaction mixture" refers to all mixture components in the autoclave in a cold degassed condition. In the following experiments with continuous processes, the liquid reaction mixture was analyzed. The fundamental difference between the experiments with batch and continuous processes is that in experiments with periodic processes in the calculations of the concentrations of the components were not taken into account the separation of the reaction components between the liquid and gaseous phases. Because of this separation, the concentration of the reaction components contained in the liquid phase during the reaction in a periodic process in the reaction conditions was similar, but not identical,as methyliodide and acetate, was characterized by a lesser concentration in the liquid reaction mixture than in the whole of the reaction mixture, whereas the concentration of water in these two variants was comparable. Thus, the speed calculated in the experiment with periodic process, for a total reaction mixture should be similar to the speed in a continuous process with the liquid mixture, which is similar to the entire reaction mixture is a batch process. In addition, the trends that were observed in experiments with periodic processes at varying variables of process parameters such as the concentration of water, were comparable with the trends that were observed in experiments with continuous processes. All experiments with batch carbonylation was performed using 300 ml of zirconium autoclave equipped with a stirrer Dispersimax (trademark), a device for input of liquid catalyst and coil refrigerators. The gas in the autoclave was filed from the tank to compensate for changes in pressure, and the gas produced to maintain in the autoclave constant pressure. At some point during the reaction speed of the gas absorption ispoljzovalosj degassed mixture in the reactor per hour (mol/l/h) at a particular composition of the reaction mixture throughout the reaction mixture in terms of the amount of cold degassed mixture).

During the reaction the concentration of acetate was calculated by the original composition, assuming that each mole of consumed carbon monoxide spent one mol of acetate. Organic components in the space of the autoclave above the liquid in the calculation was not accepted.

In each experiment with periodic carbonyliron catalyst, H2IrCl6dissolved in portions a mixture of acetic acid/water liquid contents of the reactor were loaded into the device for input of liquid. If used, the promoter, was introduced into the autoclave together with a portion (10 g) in acetic acid component. Then, the autoclave was tested on the pressure with nitrogen, the pressure is discharged through gas sampling and blew the carbon monoxide several times (3 times at a pressure 3-10 bar). The remaining liquid components of the reaction mixture were loaded into the autoclave through the hole to enter the liquid. Then in the autoclave with carbon monoxide created excessive pressure (usually 6 bar) and with stirring (1500 rpm), the contents were heated to the reaction temperature (190oC). Next, a flow of carbon monoxide from the tank to compensate for the change in total pressure gauge pressure surface is blithedale 15 min) catalyst was injected using a higher pressure of carbon monoxide. The concentration of iridium specified for these experiments with periodic processes, due to the input efficiency of the catalyst is equal to 92%. Gas supply from the tank to compensate for the pressure change during the whole experiment the excess pressure in the reactor was maintained at a constant level (0.5 bar). The absorption of gas from the tank to compensate for the pressure change over the course of the experiment was measured using the device for removing and write data. The reaction temperature is maintained at the desired reaction temperature with an accuracy of 1oC using a heating jacket connected to a regulating system Eurotherm (trademark). In addition, the excess heat of reaction was removed with coiled refrigerators. Each experiment was performed before the termination of the gas absorption. Then the capacity to compensate for the change in pressure was off and the reactor was rapidly cooled using coiled refrigerators.

H2IrCl6(aqueous solution from 22.2% (weight/weight) Ir) was supplied by Johnson Matthey. Acetic acid was obtained by carbonyliron mixed raw materials methanol/methyl acetate; it consisted of very small amounts of propionic acid and its predecessors. Methyl is(CO)12(firm STREM) and iodine (company Aldrich, 37, 655-8) and stored until use in an atmosphere of carbon monoxide in the tube Slinka placed in the freezer.

In examples 1-12 illustrate the effect of the water concentration, expressed in wt.%, the rate of the carbonylation reaction conducted using the iridium catalyst promoted with ruthenium (at a molar ratio of ruthenium:iridium approximately 2:1), at 190oC and total pressure of 28 bar. The composition of the feed materials listed in table. 1. The data rate when the estimated concentrations of acetate in the whole reaction mixture (as defined above, in a cold degassed liquid) equal to 30, 25, 20, 15, 10, 7,5 and 5 wt.%, presented in table. 2. The rate of carbonylation was calculated at different concentrations of acetate and water, and the data in accordance with the present invention (concentration of water is not more than 6.5 weight. % from the reaction mixture as a whole, cold degassed liquid) in the table is separated from the comparative data (black line). Based on these data, it was assumed that a continuous carbonylation process should be conducted in a sustainable mode using the liquid reaction mixture, the solid fuel at the same speed achieved carbonylation.

In Fig. 1 and 2 graphically shows some data from a table. 2, illustrating the effect of water concentration on the rate of carbonylation of methanol catalyzed by iridium/ruthenium respectively at 30 and 15 wt.% methyl acetate.

In Fig. 3 shows the data from table. 2 for different concentrations of acetate: 5, 7, 5, 10 and 15 wt.%.

Further experiments were carried out without ruthenium promoter. The experiments And To demonstrate the influence of water concentration (expressed in weight% the weight of the entire reaction mixture, cold degassed liquid) on the rate of carbonylation reactions conducted using only the iridium catalyst, without ruthenium promoter, at 190oC and under a total pressure of 28 bar. The composition of the feed materials listed in table. 3. The data rate when the estimated concentration of acetate, equal 30, 25, 20, 15, 10, 7,5 and 5 wt.% (expressed in wt.% from all of the reaction mixture, cold degassed liquid), are presented in table. 4.

Data mapping table. 4 only for iridium and table. 2 for iridium/ruthenium graphically shown in Fig. 4 and 5.

Comparison of the accelerating effect of ruthenium at 30 wt.% methyl acetate and various concentrations in the 2, 4 and 5 and Fig. 1-5 shows that lowering the concentration of water from more than 6.5 wt.% the rate of carbonylation increased, passing through a maximum, and then, when approaching the water concentration to a very low level, it decreased in the case of catalytic systems as with iridium and iridium/ruthenium. It is also obvious that with decreasing concentration of water as ruthenium promoter was more efficient in speeding up the ruthenium was found to be most effective when observed maximum reaction rate, which was achieved at a concentration of water is not more than 6.5 wt.%. At lower concentrations of water and 30% of the acetate reaction rate decreased simultaneously with the weakening of the accelerating effect of ruthenium.

Fig. 5 and table. 6 (comparison of experiments a, B, G and C with examples 1, 2, 3 and 7) illustrate the same point, but at a lower concentration of methyl acetate, equal to 15 wt.%.

In Fig. 3 shows that the method according to the present invention by reducing the concentration of acetate from 15 to 5 wt.% the estimated concentration of acetate in the entire reaction mixture at the optimum concentration of the water in terms of speed of reaction is shifted to a lower value.

From table. 2 and 4 Ocala 5.4 mol/l/h, when the calculated concentration of acetate 5 weight. % throughout the reaction mixture and the relatively low concentration of water equal to 2 wt.% (see example 3), observed a relatively high rate of carbonylation equal to 11.7 mol/l/h, i.e., the acceleration of the ruthenium in these conditions was large (increasing the speed at 117%), even with 2 wt.% water. Similarly, the relatively high rate of 19.2 mol/l/h was observed at 3.2 wt.% water and 10 wt.% methyl acetate (example 3).

Conducted additional experiments with periodic processes 13-16 and M the composition of the feed materials listed in table. 1 and 3. The results of the experiment M are given in table. 4, for example, 13 - in table. 2, and for examples 14-16 - in table. 7.

Experiment M demonstrates the effect of increasing concentrations methyliodide of socializaton in the case of reactions catalyzed only iridium, without promoter. From the comparison with experiment in table 3. 4 one can see that increasing the concentration under the conditions has a positive effect on the reaction rate, especially at low concentrations of water. Example 13 (PL. 2) shows the effect of increasing concentrations methyliodide of socializaton from about 8 to 12 weight. % in the case of accelerated ruthenium, katalia at low concentrations of water with increasing concentration under the conditions of 8 to 12%, the effect of accelerating the ruthenium increased (cf. experiment 3 example 7), as shown in the table. 8. The effect of increasing concentrations under the conditions of 8 to 12 wt.% 15% methyl acetate is also reflected in graphic form in Fig. 6.

Comparison of experiment 3 with experiment M (27% increase in the reaction rate when the change of concentration under the conditions of 8 to 12%) and example 7 with example 13 (58% increase in the reaction rate when the change of concentration under the conditions of 8 to 12%) shows that under these conditions promoted by ruthenium-iridium catalyst was found to be more sensitive to the concentration under the conditions than apromotional catalyst.

Examples 14-16 illustrate the effect of water concentration at various concentrations of acetate in the case of the molar ratio of ruthenium:iridium approximately 5: 1 and 8% under the conditions. These examples also demonstrate an additional positive effect on the reaction rate increasing molar ratio of ruthenium:iridium from about 2:1 (examples 1-12) to 5:1.

Examples of reactor for continuous carbonylation

To illustrate the essence of the present invention, experiments were conducted using the carbonylation reactor for continuous operation and liquid the spacecraft contained equipped with a stirrer reactor (1) for carbonyl Stripping capacity (2) and two distillation columns (3, 4), all of this equipment was made of zirconium 702. It also included two of the Packed scrubber for flue gas: optional explicilty scrubber (not shown) and methanol scrubber (5), made of stainless steel.

In the process of technical grade methanol, which is used for washing the flue gas was carbonyliron in a 6-liter reactor (1) in the presence of iridium catalyst for carbonylation and promoter under pressure 24,0-30,0 bar and at a temperature 181-195oC. the Reactor (1) was equipped with a propeller stirrer (6) and holder with reflector (not shown) providing a homogeneous mixture of liquid and gaseous reagents. Carbon monoxide is fed into the reactor from the original installation or from a thick-walled flask through a bubbler (7), mounted below the agitator (6). With the aim to minimize the access of iron in the reactor carbon monoxide was passed through a carbon filter (not shown). The temperature of the reaction liquid in the reactor can be maintained at a constant level using a shirt (not shown), which circulated hot oil. The liquid reaction mixture issledovania line (9) with a constant flow were taken under high pressure inert gases. They were passed through a refrigerator (not shown) and then through the valve (10), where the excess pressure fell to 1.48 bar, with subsequent supply to the scrubber system.

The liquid reaction mixture were taken from the reactor for carbonylation through the lower part of the stilling well (11) and sent to the Stripping tank (2) with simultaneous regulation of the liquid level in the reactor. In the Stripping vessel overpressure of the liquid reaction mixture instantly dropped to 1.48 bar. The resulting mixture of steam with the liquid separated, and rich catalyst fluid return line (12) and through the pump (13) in the reactor, and the steam was passed through demister (14) and then sent in the form of steam directly into the column (3) for the removal of light fractions. This demister consisted of two parts. The first was a net section of demister and the second nozzle section. This second section is optional washed with water material withdrawn from the head of the column for distillation of light fractions. To remove corrosion products of metals from flowing return liquid fraction from the Stripping capacity of the flow re-circulating catalyst) provided the resin layer (25) of the ion-exchange removal products is rivali below 100 hours/million

Section allocation received acetic acid this installation consisted of a distillation column (3) for the removal of light fractions with 36 plates and drying distillation column (4) with 28 plates. Both were made of Zirconia with / tube sheet plates of polytetrafluoroethylene.

Distillation column (3) worked under the same pressure, and Stripping capacity (approximately 1,48 bar), powered by steam. Below the point of power is 3 plates.

Distillation column (4) worked under pressure in the cylinder (1.8 bar) with the power fluid supplied to the 20th plate, counting from the bottom. The pressure maintained by diversion (26) of the flow of carbon monoxide in the head of the column. To minimize heat losses of the column was supplied mains electric heaters and double insulation. Network electric regulating the temperature level similar to the process temperature at a given point inside the column.

The upper straps of the distillation column (3) was passed through a refrigerator (15); exhaust gas of low pressure was supplied by a line (16) in the scrubber system, and the condensed liquid was dropped into the sump (17). This fluid performance, the EOS, while the lighter aqueous layer was separated. A number returned in the upper part of the column in the form of phlegmy, another part is not necessarily used for washing Stripping vessel, and thence sent to the reactor. The remainder of the aqueous phase was returned to the reactor via a pump (13) for the recycling of the catalyst. The distillation column (3) there was a thermosiphon boiler with electric heater (not shown) and adjusting the load of the boiler on a couple of the temperature of the liquid. Crude acetic acid was removed from the reboiler through line 18 and subjected to Stripping in the evaporator (19).

This evaporator was made of zirconium 702 and worked under atmospheric pressure with load regulation of the boiler on a couple of the fluid level. The main part of the material introduced into the evaporator, removed from the head of the evaporator in the form of steam and are condensed with the subsequent injection pump (20) in a drying column (4). Raw materials in the drying column can also be submitted in the form of steam. The bottom stream from the evaporator return line (21) in the reaction system.

In addition, instead of the evaporator of the distillation column (3) can operate with steam extraction from the lower portion through the drain well.

Suchilin is patelnie on a pair of temperature on the plate 8. The top zipper was a single-phase material. Some material from the head used for irrigation of this distillation column, and the rest was returned to the reactor. The resulting dry acetic acid were taken from the lower part of the column through line (22). The concentration of propionic acid in the resulting dry acetic acid withdrawn from the bottom of the drying column, served as an indicator of the speed of propionic acid as a by-product. For the reaction with idiscovered acid on the plate 6 of this column was filed methanol.

Departing from columns (3, 4) low-pressure gas was first passed through coolers (23) for off-gas low pressure, and the condensed liquid is returned to the sump (17). The resulting steam is combined with the waste high-pressure gas having a reduced pressure, followed by submission to the basis of the methanol scrubber (5).

Methanol scrubber (5) for off-gas contained nozzle from knitted mesh". Removal under the conditions of flow of the exhaust gas used chilled methanol. Product washing with methanol, the exhaust from the scrubber, combined with fresh methanol and submitted to have observal pressure in the Stripping vessel, and analyzed with subsequent discharge through the vent into the atmosphere.

Before the methanol scrubber exhaust gas (high pressure, low pressure or mixed) can pass through explicilty scrubber (not shown). This scrubber was identical to the methanol scrubber, but he held the nozzle in the form of "knitted mesh" alloy Hastelloy B2 and for flushing gas used approximately 10% received acetic acid. Product washing then returned to the Stripping tank. In the case of explicitating scrubber for washing flue gas low pressure refrigerators were not involved.

The results with different liquid reaction mixtures are given in table. 9.

Are given in table. 9 the results show the effect of varying the concentration of water from 7.1 to 2.2 wt.% on the rate of carbonylation reactions and formation of side products. From the data table. 9 you can see that with decreasing concentration of water from more than 6.5 to 6.5 wt.% or less than the receive rate of acetic acid was increased to a maximum (as in the examples of periodic processes), which in the specific conditions of examples 17-20 periodically interaction with the liquid reaction mixture approximately 18 wt.% methyl acetate, 4-10 wt.% methyliodide of socializaton and about 3 wt.% water. Examples 24-27 represented the interaction with the liquid reaction mixture to approximately 15 wt.% methyl acetate and about 5 wt.% water. These two sets of examples show that with increasing concentration of methyliodide of socializaton in the liquid reaction mixture, the temperature and/or concentration of the catalyst that was needed to maintain a given rate of reaction decreased while reducing the quantities of generated by-products.

Examples 28 and 29 illustrate the effect of variation in the liquid reaction mixture, the concentrations of water and methyl acetate content methyliodide of socializaton approximately 7 wt.%. Thus, reducing the concentration of water and the increase in the concentration of acetate, the temperature required to maintain the reaction rate, to decrease the quantity of generated by-products.

Experiments with periodic processes using zinc promoter

Experiments with periodic processes were performed as in examples 1-12, but using as a promoter of zinc instead of ruthenium. The composition downloadable mizvot, that by lowering the concentration of water, the reaction rate of the carbonylation increased and passed through a maximum when the concentration of water is not more than 6.5 wt.%.

1. The method of obtaining acetic acid, comprising (1) a continuous feed of methanol and/or its reactive derivative and carbon monoxide in a carbonylation reactor for, which contains the liquid reaction mixture comprising iridium carbonylation catalyst, methyliodide socialization, water in limited concentrations, acetic acid, methyl acetate and at least one promoter; (2) the introduction of methanol and/or its reactive derivative in contact with carbon monoxide in a liquid reaction mixture with obtaining acetic acid and (3) extraction of acetic acid from the liquid reaction mixture, characterized in that that during the interaction in the liquid reaction mixture is continuously support (a) the water concentration is not more than 6.5 wt.%, (b) the concentration of acetate in the range from 1 to 35 wt.% and (C) concentration under the conditions within 4 to 20 wt.%.

2. The method according to p. 1, in which during the interaction in the liquid reaction mixture is continuously maintain the concentration of water is not more than 6 wt.%.

3. Sposobnostey water of at least 0.1 wt.%.

4. The method according to p. 3, in which the entrance of the venue of interaction in the liquid reaction mixture is continuously maintain the concentration of water at least 1 wt.%.

5. The method according to any of the preceding paragraphs, in which the interaction between the concentration of methyl acetate in the liquid reaction mixture is continuously maintained within the range of 1 to 30 wt.%.

6. The method according to p. 5, in which during the interaction, the concentration of methyl acetate in the liquid reaction mixture is continuously maintained within the range of 5 to 25 wt.%.

7. The method according to any of the preceding paragraphs, in which the interaction between the concentration of methyl acetate in the liquid reaction mixture is continuously maintained within the range of 5 to 16 wt.%.

8. The method according to any of the preceding paragraphs, in which at least one promoter selected from the group consisting of ruthenium, osmium, rhenium, cadmium, mercury, zinc, gallium, indium and tungsten, preferably from the group consisting of ruthenium and osmium.

9. The method according to p. 8, in which the molar ratio of promoter : iridium is (0,5 - 15) : 1.

10. The method according to p. 1, in which during the interaction in the liquid reaction mixture is continuously support the contents of the device within 400 - 3000 ppm and the concentration of ruthenium promoter in the range 400 - 4000 h/million

11. The method according to any of the preceding paragraphs, in which the partial pressure of hydrogen in the carbonylation reactor for less than 1 bar, more preferably less than 0.5 bar and most preferably less than 0.3 bar.

12. The method according to any of the preceding paragraphs, in which the amount of hydrogen in the carbon monoxide as the reagent is less than 1 mol.%, more preferably less than 0.5 mol.% and most preferably less than 0.3 mol.%.

Priority points:

21.06.1995 - PP.1 and 8 (gallium, indium, osmium, ruthenium);

19.07.1995 - PP.1 and 8 (cadmium, rhenium, mercury, zinc, tungsten);

06.10.1995 - PP.9 and 10;

23.11.1995 - PP.2 - 7 and 11 - 12.

 

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