JP5894297B2 - Catalyst recovery using aqueous hydrogen iodide and acetic acid - Google Patents

Description

BACKGROUND OF THE INVENTION This invention relates to a process for recovering catalyst value from tar produced during the preparation of acetic anhydride by carbonylation of methyl acetate, dimethyl ether or a combination of the two. More particularly, the present invention relates to a method for recovering valuable materials that are not normally extractable from tar.

  The carbonylation process to produce acetic anhydride produces tar as a by-product. The production of tar and the problems it causes in the recovery of catalyst valuables are described, for example, in US Pat. Nos. 4,388,217 and 4,944,927, European patent applications EP0087870 and EP0008396, and publication No. 91/07372, which is described in the PCT application specification. One problem with tar formation is that tar interferes with catalyst recovery and reuse, as discussed in some of the above applications. An extraction method has been developed to separate the catalyst into the aqueous phase from the tar contained in the organic phase, such as a methyl iodide solution. However, due to the high cost of many catalyst components, there is a continuing need to improve the efficiency of methods for separating the catalyst from tar and thereby recovering the catalyst.

BRIEF SUMMARY OF THE INVENTION The present invention provides a method for recovering a catalyst from a liquid comprising catalyst and tar. In some embodiments, the method comprises subjecting the liquid to at least one aqueous solution and methyl iodide comprising acetic acid and hydrogen iodide, an aqueous phase comprising acetic acid and hydrogen iodide, and an organic phase comprising methyl iodide. Combining under conditions effective to cause formation, wherein at least a portion of the catalyst is concentrated in the aqueous phase. The method further includes feeding a liquid comprising catalyst and tar to a primary feed location on the container, feeding at least one aqueous solution comprising acetic acid to at least one aqueous feed location on the container, wherein aqueous The feed position is vertically below the main feed position, recovering at least a portion of the organic phase from the container at the organic phase recovery position, wherein the organic phase recovery position is vertically below the main feed position; and Recovering at least a portion of the aqueous phase from the container at an aqueous phase recovery position, wherein the aqueous phase recovery position is vertically above the main feed position. Optionally, this embodiment can further comprise feeding at least one liquid stream comprising methyl iodide to at least one organic feed location on the vessel, wherein the at least one organic feed location is the primary feed location. Located vertically above the position.

  In some embodiments, the method comprises, in the presence of hydrogen iodide and methyl iodide, a liquid comprising a catalyst and tar, at least one aqueous solution comprising acetic acid, an aqueous phase comprising acetic acid and hydrogen iodide, and Combining under conditions effective to cause the formation of an organic phase comprising methyl iodide, wherein at least a portion of the catalyst is concentrated in the aqueous phase, the method further comprising: catalyst and tar Feeding said liquid comprising a main feed position on said container, feeding at least one liquid stream comprising methyl iodide to at least one organic feed position on said container, wherein said at least one organic feed The at least one aqueous solution containing acetic acid is at least one aqueous feed on a container at a location vertically above the main feed location. Feeding to a location, wherein the aqueous feed location is vertically below the primary feed location, recovering at least a portion of the organic phase from a container at an organic phase recovery location, wherein the organic phase The recovery position is vertically below the main feed position, and at least a portion of the aqueous phase is recovered from the container at the aqueous phase recovery position, wherein the aqueous phase recovery position is vertically above the main feed position Including.

  In some embodiments, the liquid comprising the catalyst and tar further comprises methyl iodide, acetic acid, hydrogen iodide, or a combination of two or three thereof. In some embodiments, the combining is performed in the presence of elemental iodine. For example, the liquid comprising the catalyst and tar can include at least a portion of elemental iodine fed to the reactor.

  In some embodiments, the at least one aqueous solution comprising acetic acid comprises hydrogen iodide, but comprises a first solution that does not contain acetic acid and a second solution that contains acetic acid but does not contain hydrogen iodide. it can. In some embodiments, the at least one aqueous solution comprising acetic acid comprises at least one single solution comprising both hydrogen iodide and acetic acid.

  In some embodiments, the catalyst comprises at least one Group VIII metal. In some embodiments, the at least one Group VIII metal is rhodium.

  In some embodiments, the at least one aqueous phase recovery location is vertically above the at least one organic feed location. In some embodiments, the at least one organic phase recovery location is vertically below the at least one aqueous feed location. In some embodiments, the container includes an upper vertical trisection, a middle vertical trisection and a lower vertical trisection, and at least one aqueous feed position is in the lower vertical trisection of the container. In some embodiments, the at least one organic feed location is in the upper vertical tri-section of the container. In some embodiments, the container includes a column, and the column includes at least one reciprocating plate agitator.

  In some embodiments, 22.5% to 55% by weight of all materials fed to the container is acetic acid. In some embodiments, 0.5-10% by weight of all materials fed to the container is hydrogen iodide.

Brief Description of Drawings
FIG. 1 is a graph showing rhodium extraction efficiency using aqueous solutions having various acetic acid and hydrogen iodide concentrations. The data is shown in Table 2B. The acetic acid concentration of the composition is shown on the x-axis. Rhodium extraction efficiency is shown on the y-axis. Diamond-shaped data points represent solutions with a hydrogen iodide concentration of 2%. Square data points represent solutions with hydrogen iodide concentrations above 4%.

FIG. 2 is a graph showing the percentage of catalyst extraction obtained in the laboratory separation of a liquid containing catalyst and tar. The data is shown in Table 3B. The x-axis represents% acetic acid in the total composition. Rhodium extraction efficiency is shown on the y-axis. Square data points indicate the percent extraction efficiency of the extract whose composition contains 8% hydrogen iodide, and the amount of acetic acid is indicated by the x-axis. Diamond-shaped data points indicate the percentage extraction when the hydrogen iodide level is 0%.

DETAILED DESCRIPTION The present invention provides a method for separating catalyst components from tar by concentrating in an aqueous phase. Liquid containing catalyst and tar causes formation of an aqueous phase containing acetic acid and hydrogen iodide and an organic phase containing methyl iodide in the presence of at least one aqueous solution containing acetic acid and hydrogen iodide and methyl iodide. Combine under effective conditions. As used throughout this specification, “hydrogen iodide”, “iohydroic acid, hydroiodic acid” and “HI” should be used interchangeably. The process achieves more efficient catalyst recovery than either aqueous HI alone or aqueous acetic acid alone. It has been found that combining a liquid containing catalyst and tar with both aqueous HI and aqueous acetic acid results in a higher concentration of catalyst in the aqueous phase than the use of acetic acid alone or HI alone. The combination of aqueous HI and acetic acid can be used as a primary extraction technique or a secondary extraction technique after pre-extraction to recover rhodium that cannot be extracted only with aqueous HI. As used throughout this specification, a percentage, part or other indication of a partial component of the composition refers to the weight percentage of the component, unless otherwise specified.

Liquid comprising or comprising a catalyst and tar The liquid subjected to the method of the present invention, referred to herein as “liquid comprising catalyst and tar” or “liquid comprising catalyst and tar”, comprises at least the catalyst and tar. , And many additional ingredients can be included. Tar refers to the type of compound produced as a by-product of methyl carbonylation and downstream processes. Tars are described, for example, in U.S. Pat. Nos. 4,388,217 and 4,944,927. The catalyst may be any effective catalyst that can be separated from the tar using the methods set forth herein. In some embodiments, the catalyst comprises one or more Group VIII noble metals (ie, selected from iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum or combinations thereof). In some embodiments, the catalyst comprises one or more Group VIII noble metals (ie, selected from ruthenium, rhodium, palladium, osmium, iridium or platinum or combinations thereof). In some embodiments, the Group VIII metal is selected from nickel, rhodium and iridium or combinations thereof. In some embodiments, the metal is a nickel compound. In some embodiments, the metal is a rhodium compound. In some embodiments, the metal is an iridium compound. The metal can be present in any state of ionization or coordination, including, for example, as a metal, as a salt, or a complex such as a carbonyl complex.

  Catalyst and tar will be included in the liquid material. The liquid can have any suitable composition, and the composition of the liquid will depend on the source from which it is derived. In some embodiments, the liquid comprising the catalyst and tar is prepared by combining tar with one or more liquids. In some embodiments, the tar is diluted with methyl iodide. In some embodiments, the liquid is derived from a methyl acetate carbonylation process. “Origin” means that the liquid comes directly from such a process or from a particular downstream device associated with such a process, such a process is as described below. Some example liquid components can include methyl iodide, acetic acid, water, ethylidene diacetate, acetone, acetic anhydride, methanol, or combinations of two or more of the above. Other components include, for example, iodine-containing compounds (eg, lithium iodide) and residual compounds from accelerators used in carbonylation reactions (eg, lithium compounds, chromium compounds, nitrogen-containing compounds, eg, amine accelerators). Those resulting from the use, and those resulting from the use of phosphorus compounds such as phosphine promoters). The present invention is useful for particularly difficult processes that recover one or more catalyst metals present in very small concentrations, such as when a portion of the catalyst metal has already been removed. Thus, in some embodiments, the amount of one or more catalytic metals in the liquid comprising the catalyst and tar is less than 10% prior to processing. In some embodiments, this amount is less than 7.5%, less than 5%, less than 3%, less than 2%, less than 1%, or less than 0.5%. In some embodiments, the amount of one or more catalytic metals present before treatment is at least 0.001%, at least 0.01%, or at least 0.05%.

  Tar is also present in the liquid composition. In some embodiments, the catalyst and tar containing liquid comprises tar in an amount of less than 30%. In many embodiments, the amount of tar is less than 20%, less than 15%, less than 10%, less than 7.5%, less than 5%, less than 3%, less than 2%, less than 1% or less than 0.5%. is there. In some embodiments, the amount of tar present can be 0.5-20%, 0.5-10%, or 0.5-7.5%.

  In some embodiments, at least 50% of the total liquid composition is methyl iodide and / or acetic acid. In some embodiments, this amount is at least 60%, at least 70%, or at least 80%. In some embodiments, this amount is 60-95%. In some embodiments, this amount is 70-90%. In some embodiments, at least 30% of the composition is methyl iodide. In some embodiments, this amount is at least 40%, at least 50%, or at least 60%. The methyl iodide levels in some other example compositions are 30-90%, 35-80%, 40-70%, 45-65% and 70-90%. In some embodiments, at least 20% of the composition is acetic acid. In some embodiments, this amount is at least 25%, at least 30%, or at least 40%. Acetic acid levels in some example compositions are 20-50%, 20-40%, 25-50%, 30-50%, 25-40%, 35-45%, and 30-40%.

  In addition to methyl iodide, other iodine-containing compounds may also be present. As used throughout this specification, “iodine-containing compound” means any compound containing at least one iodine atom. Examples include methyl iodide, elemental iodine, acetyl iodide, hydrogen iodide and lithium iodide. In some embodiments, when lithium is present, the liquid containing the catalyst and tar contains lithium iodide in an amount of less than 20%. In some embodiments, the amount of lithium iodide is less than 15%, less than 10%, less than 7.5%, less than 5%, less than 3%, less than 2%, less than 1%, or less than 0.5% . In some embodiments, the amount of lithium iodide present is 0.5-20%, 0.5-10%, or 0.5-7.5%.

  In view of the advantages of the presence of elemental iodine as taught in the PCT application of WO 91/07372, in some embodiments, elemental iodine is another iodine-containing compound that can be present. In some embodiments, the liquid comprising catalyst and tar comprises elemental iodine in an amount of less than 15%. In some embodiments, elemental iodine is in an amount less than 10%, less than 7.5%, less than 5%, less than 3%, less than 2%, less than 1%, or less than 0.5%. In various embodiments, the amount of elemental iodine present can be 0.5-10%, 0.5% -7.5%, or 0.5-5%.

  Water can also be present. In some embodiments, the liquid comprising catalyst and tar comprises an amount of water less than 20%. In some embodiments, the amount of water is less than 15%, less than 10%, less than 7.5%, less than 5%, less than 3%, less than 2%, less than 1% or less than 0.5%. In some embodiments, the amount of water present is 0.5-20%, 0.5-10%, or 0.5-7.5%. In some embodiments, sufficient water is present to ensure that the amount of acetic anhydride is, for example, less than 0.01%, less than 0.001%, or undetectable in the composition.

  Methyl acetate may also be present. However, in some embodiments, methyl acetate can function as a co-solvent for the aqueous phase and methyl iodide in the organic phase, limiting the ability of the phase to separate and therefore should be limited It is. In some embodiments, the amount of methyl acetate is less than 20%, less than 15%, less than 10%, less than 7.5%, less than 5%, less than 3%, less than 2%, less than 1% or 0.5% Is less than. In some embodiments, the amount of methyl acetate present is 0.001-15%, 0.001-10%, 0.001-7.5%, 0.001-5%, or 0.001-2. 5%.

  Ethylidene diacetate (EDA), a by-product of methyl acetylation of acetate, can also be present. In some embodiments, the amount of EDA is less than 15%, less than 10%, less than 7.5%, less than 5%, less than 3%, less than 2%, less than 1%, or less than 0.5%. In some embodiments, the amount of EDA present is 0.001-20%, 0.001-10%, 0.001-7.5%, 0.001-5%, 0.001-2.5. % Or 0.001 to 1%. Acetone is also a by-product, which may also be present. In some embodiments, the amount of acetone is less than 15%, less than 10%, less than 7.5%, less than 5%, less than 3%, less than 2%, less than 1%, or less than 0.5%. In some embodiments, the amount of acetone present is 0.001-20%, 0.001-10%, 0.001-7.5%, 0.001-5%, 0.001-2.5. % Or 0.001 to 1%.

  Any combination of the above compositions is within the scope of the present invention. Thus, for example, in some embodiments, the liquid composition comprises 30-90% methyl iodide, 15-50% acetic acid, 0.001-10% catalytic metal, 0.5-20% tar. 0.5-5% lithium iodide, 0.5-10% elemental iodine, 0.5-20% water. Such embodiments may further comprise 0.001-20% methyl acetate, 0.001-20% acetone and 0.001-20% EDA. As another example, in some embodiments, the liquid composition is 40-60% methyl iodide, 20-40% acetic acid, 0.001-1% catalytic metal, 0.5-7.5%. Of tar, 0.5-5% lithium iodide, 0.5-10% elemental iodine, 0.5-5% water. Such an embodiment may further comprise 0.001-2.5% methyl acetate, 0.001-1% acetone and 0.001-1% EDA.

In some embodiments, the process by which the liquid containing catalyst and tar is obtained includes methyl acetate, dimethyl ether, or both by reaction with carbon monoxide at high pressure and temperature in the presence of the catalyst and iodine compound. Preparation of acetic anhydride by liquid phase carbonylation, wherein a feed mixture containing methyl acetate, dimethyl ether or both is continuously fed to a carbonylation reactor and a reaction mixture containing acetic anhydride is continuously removed Is mentioned. Optionally, the reaction may be performed in the presence of one or more inorganic or organic promoters such as one or more lithium compounds, chromium compounds, amine promoters or phosphine promoters, or combinations thereof. In some embodiments of the process, the feed to the reactor is such that it is maintained within the reaction mixture of reactants, catalyst, promoter and methyl iodide. The remainder of the reactor content contains primarily acetic anhydride product and small amounts of by-products such as ethylidene diacetate and acetone. The reactor feed can optionally include a solvent such as acetic acid, for example, in an amount that maintains about 5-40% by weight in the reaction mixture. In some embodiments, the carbon monoxide in the feed gas can include hydrogen.

  In some embodiments, the carbonylation process is a simultaneous production of acetic acid and acetic anhydride by including water and / or methanol in the reactor feed, for example as described in EP 0087870. Is a method designed for. In some embodiments, the carbonylation process is a process for the production of ethylidene diacetate or the simultaneous production of ethylidene diacetate and acetic anhydride, such as methyl acetate and / or dimethyl ether and methyl iodide for hydrogen and monoxide. By contacting with a mixture of carbon, for example, as described in Belgian Patent No. 839,321.

The carbonylation process can be performed, for example, in a liquid or gas take-off mode of operation. In some embodiments of the liquid take-off device, catalyst components such as catalyst, promoter, methyl iodide and unreacted methyl acetate, dimethyl ether or both are recovered from the reaction effluent and recycled. In some embodiments, fresh metal catalyst and fresh promoter are added to the catalyst recycle. The fresh ingredients can optionally be added as a solution in acetic acid. In some embodiments, the iodine-containing compound can be replenished by adding elemental iodine (I ₂ ), methyl iodide, or at least partially as lithium iodide. In a gas take-off device, many catalyst components remain in the reactor, so that the risk of its depletion from the process is significantly reduced.

Treatment Before Combining Steps In some embodiments, the liquid comprising the catalyst and tar can be obtained continuously or intermittently from the carbonylation process, for example, by a mixture of compounds present in the system. Such a mixture may be withdrawn from either the reactor or downstream equipment. For example, in an apparatus that uses a liquid product take-off from the reactor, liquid can be removed from several points in the catalyst recycle stream. The mixture can then function as a liquid containing catalyst and tar, or can be further processed to form a liquid containing catalyst and tar. In some embodiments, the stream from the carbonylation process is reduced, for example by evaporation, and then optionally combined with one or more other liquids, such as one or more liquids containing methyl iodide. In some embodiments, further processing includes filtration. In some embodiments, further processing is stripped in a flash evaporator, followed by a stirred stripped tar similar to that taught in Example 12 of US Pat. No. 4,388,217. Combining with other liquids in the receiver and then filtering the material from the stripped tar receiver and feeding it to the combining process. In some embodiments, the liquid is combined with methyl iodide in a stripped tar receiver or otherwise before introduction into the combination process. In some embodiments, hydrogen iodide is also fed to the stripped tar receiver, where it reacts with lithium acetate (if present in the stripped tar receiver feed) to produce lithium iodide and acetic acid. Water can be fed to the stripped tar receiver where it can react with residual acetic anhydride (if present in the stripped tar receiver) to produce acetic acid. In some embodiments, the presence of HI in the receiver can stabilize the catalyst and reduce the likelihood that the catalyst will settle and deposit on the receiver and downstream equipment walls. In some embodiments, the stripped tar receiver and the apparatus in which the combination process is performed transfer a portion of the HI and water used in the combination process from the combination process to the stripped tar receiver, and the stripped tar receiver To function as a source of HI and water.

In some embodiments, elemental iodine is added during upstream processing by combining with a liquid containing catalyst and tar prior to extraction or by adding during the extraction process. A combination method of elemental iodine can be found, for example, in the PCT application specification of Publication No. 91/07372. Any effective amount of elemental iodine can be added to the system. In some embodiments, the amount of elemental iodine present in the liquid comprising catalyst and tar is 0.5 per mole of metal catalyst (eg, per mole of [Rh] when the metal catalyst is rhodium). 100 parts a of _{I 2.} In some embodiments, elemental iodine is used in an amount that provides 3 to 20 parts of I ₂ per mole of metal catalyst.

Process Combining Step The method comprises combining a liquid containing catalyst and tar with an amount of aqueous acetic acid in the presence of hydrogen iodide and methyl iodide, and removing the catalyst valuable from the liquid containing catalyst and tar. Can be used to concentrate to the aqueous phase. “Concentrate” means that a larger amount of mass-based catalyst valuables are included in the aqueous phase than in the organic phase. Ionic catalyst species, such as anionic rhodium species present in some liquids including catalyst and tar, are soluble in the amount of methyl iodide normally used in the process of the present invention. However, in the presence of water, the ionic species are preferentially dissolved in the aqueous phase. It has been found that the presence of both HI and acetic acid in the aqueous phase also results in higher levels of catalyst in the aqueous phase than when using HI alone or acetic acid alone. While not wishing to be bound by any particular theory, HI can affect various catalyst complexes present in the organic phase rather than acetic acid, in each case preferential in the aqueous phase Will be converted to one or more complex ionic species that will dissolve in a selective manner.

  The liquid containing catalyst and tar is combined with at least one aqueous solution containing acetic acid. In some embodiments, the at least one aqueous solution also includes HI. In some embodiments, a single aqueous solution containing both acetic acid and HI is combined with a liquid containing catalyst and tar. In some embodiments, at least two aqueous solutions are combined with a liquid comprising a catalyst and tar. When using two or more solutions comprising both HI and acetic acid, at least a portion of acetic acid and HI may optionally be included in separate solutions, or both in multiple solutions. May be included in different amounts. Similarly, two or more solutions may optionally be combined at the same time as the catalyst and tar containing liquid, or may be combined at different times or locations. As noted above, the liquid containing the catalyst and tar can include acetic acid, HI, water, or a combination of two or more thereof prior to the combining step.

  The amount of acetic acid combined with the catalyst and tar containing liquid and, if applied, the amount of HI varies based on various process factors, including the composition of the liquid containing catalyst and tar, combined with the liquid. If the amount and components of additional methyl iodide to be combined are combined, the order and configuration of the apparatus for performing the combination can be mentioned. The HI level is, for example, the desired pH, the level of HI already present in the solution containing the catalyst and tar (if any), and the acetate ion (if present) present in the liquid converted to acetic acid. It depends on whether you want to let them. The acetic acid level is sufficient to assist in the separation, but should not be so high as to interfere with the separation from the aqueous and organic phases. Furthermore, high acetic acid levels in the aqueous phase can increase tar solubility in the aqueous phase. The improvement in catalyst solubility afforded by the additional acetic acid in the aqueous phase should be balanced against these considerations.

  As described above, the one or more aqueous solutions include acetic acid. In some embodiments, the one or more aqueous solutions comprise 0.5-80% acetic acid. In some embodiments, the one or more aqueous solutions comprise 10-70% acetic acid. In some embodiments, the one or more aqueous solutions comprise 10-50% acetic acid. In some embodiments, the one or more aqueous solutions comprise 15-40% acetic acid.

  In some embodiments, the one or more aqueous solutions also include HI. In some embodiments, the one or more aqueous solutions comprise 20-70% HI. In some embodiments, the one or more aqueous solutions comprise 40-70% HI. In some embodiments, the one or more aqueous solutions comprise 30-60% HI. In some embodiments, the one or more aqueous solutions comprise 0.5-20% HI. In some embodiments, the one or more aqueous solutions comprise 10-20% HI. One or more aqueous solutions may optionally contain other components that do not unduly interfere with the functioning of the process. For example, the aqueous solution can contain elemental iodine. Other components present in the composition can depend on the source of water, HI and acetic acid, and some examples of other possible components include corrosive metals, methyl acetate, acetone or combinations thereof. Thus, in some embodiments, one or more aqueous solutions fed to the extractor (collectively if multiple streams are used) are 0.5-30 wt% HI, 0.5-60 wt% acetic acid, 20-98 wt% water, and optionally less than 1 wt% elemental iodine. In some embodiments, the one or more aqueous solutions comprise 10-20% HI, 15-40% acetic acid, 40-75% water, and optionally less than 1% elemental iodine. When using two or more aqueous solutions, they can have the same or different compositions, and the percentages described above may optionally be viewed as describing such two or more stream aggregate compositions. it can.

  The combination process is performed in the presence of HI and methyl iodide under conditions effective to cause the formation of an aqueous phase containing acetic acid and hydrogen iodide and an organic phase containing methyl iodide. As noted above, in some embodiments, at least a portion of the HI may be present by being present in one or more aqueous solutions. Alternatively, HI may be present by the presence of HI in the liquid containing the catalyst and tar, or may come from both locations. Similarly, in some embodiments, at least a portion of methyl iodide is present in the liquid comprising the catalyst and tar. In some embodiments, the additional stream comprising methyl iodide is combined with a liquid comprising catalyst and tar. In some embodiments, methyl iodide is present both in the liquid comprising the catalyst and tar and in the additional stream with which the liquid is combined. If an additional stream comprising methyl iodide is used, other components may be optionally included that do not unduly interfere with the functioning of the process. Some examples of additional components that may be present include elemental iodine, methyl acetate, water, acetic acid and acetone.

  Since acetic acid, HI, water and methyl iodide can also be liquid components including catalyst and tar, the amount of these components present or added is a fraction of the total feed to the combination process or Can be considered as a percentage. That is, it can be considered as part or percentage of a liquid composition containing catalyst and tar, one or more aqueous solutions containing HI, acetic acid or both, and any stream combination composition containing methyl iodide. In some embodiments, the total amount of HI fed to the combination process is 0.5-15% of the total feed to the combination process. In some embodiments, the total amount of HI fed is 0.5-10% or 0.5-5% of the total feed to the combination process. In some embodiments, enough hydrogen iodide is used so that in some embodiments less than 1 so that the pH of the aqueous phase is 2 or less.

  In some embodiments, the total amount of methyl iodide fed to the combination process is 20-80% of the total feed to the combination process. In some embodiments, the total amount of methyl iodide fed is 30-70% of the total feed to the combination process. In some embodiments, this number is 35-65%.

  In some embodiments, the total amount of acetic acid fed to the combination process is 0.5-55% of the total feed to the combination process. In some embodiments, the total amount of acetic acid is 10-50% or 20-40% of the total feed to the combination process. However, some considerations are factors regarding the acetic acid content. In some embodiments, it has been found that the beneficial effect of acetic acid on the recovery of the catalyst in the aqueous phase increases fairly rapidly at a feed rate greater than 20% based on the total feed to the combination process. At the same time, as noted above, the increase in the total amount of acetic acid to the combination process should be balanced against considerations that can hinder the maintenance of a separate phase in solution. This is a function of the amount of water and methyl iodide present and can be readily ascertained from the literature describing phase separation of solutions containing acetic acid, methyl iodide and water. One such example is E. T. Shepelev et al., Zhurnal Prikladnoi Khimii Vol. 64, No 11, P. 2441-2443, November 1991. In addition, higher levels of acetic acid may result in undesirable levels of tar remaining in the resulting aqueous phase. Thus, in some embodiments, the amount of acetic acid fed to the combination process is 22.5% -55% based on the total feed, and in some embodiments 25-40%.

  In some embodiments, the combination is performed in a batch process, for example, in a tank, column or other vessel. In some embodiments, the combination is performed continuously, such as in a continuous extraction vessel such as an extraction column. The vessel or column can optionally be equipped with internal structures that allow mixing such as baffles, trays or combinations thereof. Agitation mechanisms such as one or more impellers, one or more reciprocating agitators, or both may be used. In some embodiments, the container is a column with at least one reciprocating agitator, the agitator comprising a plate. In some embodiments, the column is a Karr Reciprocating Plane Extraction Column.

  The combination is performed under conditions effective to cause the formation of an aqueous phase containing acetic acid and hydrogen iodide and an organic phase containing methyl iodide, with at least a portion of the catalyst being concentrated in the aqueous phase. Any valid condition may be used. In some embodiments, the combination is performed in a container, e.g., a decanter that allows vertical separation of different phases, or a column such as a column that allows two or more streams to flow in a generally countercurrent manner. To do. “Substantially countercurrent” means that the flow of two or more flows as a whole is in opposite directions, but local regions of the flow in other directions can be observed by feed or offtake points. In some embodiments, the liquid containing the catalyst and tar moves in a generally countercurrent manner relative to the aqueous stream, the stream containing methyl iodide, or both. In some embodiments, the liquid comprising catalyst and tar is fed to a column, where both the aqueous stream and the stream comprising methyl iodide are fed in a generally countercurrent manner. The position depends in part on the various feeds and the relative concentrations of the resulting streams. For example, in some embodiments where the resulting aqueous phase is less dense than the resulting organic phase (eg, an organic phase based on methyl iodide), the combination is a feed for a liquid comprising a catalyst and tar. Can be performed in a container in which at least a portion of at least one aqueous solution is fed to a position vertically below the point, and the resulting aqueous phase is located vertically above the feed position for the liquid containing catalyst and tar. And the resulting organic phase is withdrawn from a position vertically below the feed position for the liquid containing catalyst and tar. Their location depends in part on the desired degree of countercurrent, the design and interior of the container, and the overall flow rate of each flow.

  In various embodiments, the feed location for at least a portion of the one or more aqueous solutions is the bottom vertical portion 80%, the bottom vertical portion 60%, the bottom vertical half, the bottom vertical 40%, the bottom vertical 1/3, the bottom of the container. It can be 30% vertical, 20% lower vertical, or 10% lower vertical. In some embodiments, a separate organic stream can be added. In some embodiments where an organic stream comprising methyl iodide is added and the resulting aqueous phase is less dense than the resulting organic phase, at least a portion of the organic stream is the upper vertical half of the container, 40% above the vertical , Top vertical 1/3, top vertical 30%, top vertical 20% or top vertical 10%.

  Similarly, in various embodiments, the location where at least a portion of the organic phase is removed from the container is: bottom vertical 60%, bottom vertical half, bottom vertical 40%, bottom vertical 1/3, bottom vertical 30%, bottom It can be 20% vertical or 10% lower vertical. Similarly, in various embodiments, at least a portion of the aqueous phase is removed from the container at the top vertical 60% of the container, the top vertical half, the vertical 40%, the top vertical 1/3, the top vertical 30%, the top vertical. 20% or top vertical 10%.

  The container configuration can also be described as a percentage of the total height of the container between the different addition points. In some embodiments, the distance between the addition positions of the one or more aqueous solutions is at least 10% of the container height below the point where the liquid containing catalyst and tar is added. In other embodiments, the distance is at least 20%, at least 30%, at least 40%, at least 50%, or at least 60% below the feed point to which the catalyst and tar-containing liquid is added. Similarly, in some embodiments, the distance between the addition locations for the organic stream is at least 10% of the vessel height above the point where the catalyst and tar containing liquid is added. In other embodiments, this number is at least 20%, at least 30%, at least 40%, at least 50%, or at least 60% above the feed point for the liquid comprising catalyst and tar.

  Feed liquid containing catalyst and tar at any point (primary feed point) above the aqueous feed point and below the organic feed point if the organic phase containing methyl iodide is fed. Can do.

  In embodiments where the resulting organic phase is less dense than the aqueous phase, the positions indicated in the three paragraphs above can be reversed. That is, the primary feed point for the liquid containing catalyst and tar is below one or more aqueous feed locations and one or more organic phase recovery locations, and is one or more organic phase feed locations and one or more aqueous. Above the phase recovery position. Similarly, in such an embodiment, the position described as “upper vertical 1/3” above may be at “lower vertical 1/3” and “20% of the container height above other positions”. The location described as “%” can be “20% of the container height below other locations” or the like. As used throughout this application, a reference to the position described as the “top” or “bottom” vertical fraction of a container refers to the overall height of the container from the vertical top or bottom of the container. Means the vertical height within the reference fraction. For this reason, the position in the “top 40%” of a container that is 100 meters high is within 40 meters from the top of the container, and the position in the “bottom half” of such a container is 50 meters from the bottom of the container. Is within. Similarly, references in this application relating to locations on a container that are “vertically upward” or “vertically downward”, whether directly above or below, may be more than the other locations. Mean that they are at a high or low height, or their positions are aligned circumferentially or horizontally.

  As noted above, in some embodiments, the container is an offtake for transferring the components of the container, such as stripped tar, received as described in US Pat. No. 4,388,217 to upstream equipment. It can also have a position. Such an offtake is 20% vertical at the top of the container. Top Vertical 1/3, Top Vertical 40%, Top Vertical 50%, Top Vertical 60%, Top Vertical 70%, Bottom Vertical 70%, Bottom Vertical 60%, Bottom Vertical 50%, Bottom Vertical 40%, Bottom Vertical 1 / It can appear at 3 or the bottom vertical 20% point. The height of the container will depend on the location of other feeds and offtakes and the desired composition of the feed to other devices.

  In some embodiments, some combinations occur in a series of columns, other containers, or other separation processes. For example, in some embodiments, the liquid containing the catalyst and tar has already undergone an extraction process with aqueous HI and is combined with an aqueous solution of both HI and acetic acid in the second step. Such a secondary extraction process can be similar to the primary extraction process, such as in the concentration of HI and acetic acid in the aqueous mixture.

  In some cases, the combination is performed in the presence of elemental iodine. As noted above, elemental iodine can be present in the liquid containing catalyst and tar as a result of upstream processing. Elemental iodine can be combined with the liquid containing the catalyst and tar during the combination process, or can be present through the combinations described above.

Subsequent treatment As described above, the combining step forms an aqueous phase enriched in the catalyst. The catalyst can then be reused in the carbonylation process. Prior to such a carbonylation step, the aqueous phase is further processed prior to reuse, for example, concentrating the catalyst, thereby reducing the amount of water, and then returning the aqueous phase to the process. By doing so, the amount of acid anhydride degradation caused by water, which can greatly affect the overall acid anhydride yield of the process, can be reduced. A secondary advantage of the use of acetic acid in the combination process is to replace some of the water in the resulting aqueous stream with acetic acid. This further reduces the need to separate the liquid from the catalyst by reducing the amount of water that reacts with acetic anhydride.

  This organic phase containing methyl iodide and tar is separated, for example, by distillation, and the methyl iodide recovered in this process is optionally reused in a combination step, or else methyl acetate carbonylation. It can be used in any number of aspects of the law and related equipment. The viscous tar-methyl iodide residue can be treated to further remove any iodine or catalyst value present. Some examples of methods for such treatment include pyrolysis with or without deposition on a solid support, precipitation from solution, and adsorption. The above example is disclosed in US Pat. No. 4,476,237.

EXAMPLES The present invention may be further illustrated by the following examples of preferred embodiments thereof, which are included for illustrative purposes only and limit the scope of the invention unless specifically indicated otherwise. It will be understood that this is not intended. In Comparative Examples A and B, all rhodium concentrations and amounts provide the amount of rhodium complex (Rh (CO) ₂ I ₂ ) ^{− in} the examples reported below. In laboratory experiments 1-38, the rhodium concentration is based on rhodium only, not a complex.

Comparative Example A
Average concentration, 72 parts methyl iodide, 5 parts acetone, 244 parts methyl acetate, 377 parts acetic acid, 643 parts acetic anhydride, 10 parts ethylidene diacetate (EDA), 11 parts lithium iodide, 21 A catalyst-tar solution comprising parts of lithium acetate (LiOAc), 5.3 parts of rhodium and 75 parts of tar is disposed as described in Example 12 of US Pat. No. 4,388,217. In a rectified flash still, filter and continuous countercurrent rectification extraction column. Model the filtered stream fed from the stripped tar receiver to a position above the extractor midpoint, with an average concentration of 1113 parts methyl iodide, 1 part acetone, 28 parts methyl acetate, 40 parts water, 6.6 parts rhodium, 503 parts acetic acid, 8 parts EDA, 76 parts lithium iodide, 49 parts iodine and 95 parts tar. The stream taken from the midpoint of the continuous extractor and recycled to the stripped tar receiver is modeled to average concentration, 182 parts methyl iodide, 1 part acetone, 1.2 parts rhodium, 4 parts Contains methyl acetate, 88 parts water, 91 parts acetic acid, 1 part EDA, 20 parts lithium iodide, 13 parts HI, 15 parts iodine and 20 parts tar. The methyl iodide stream fed to the upper part (above the feed point from the stripped tar receiver) contains an average concentration, 240 parts methyl iodide, 0.2 parts methyl acetate and 0.3 parts water. . An aqueous HI solution containing 375 parts water, 58 parts HI and 1 part iodine is fed to the lower part of the extractor (below the feed point from the stripped tar receiver).

  An overflow stream mainly comprising an aqueous phase containing acetic acid and most of the catalyst valuables and an underflow stream mainly comprising an organic methyl iodide phase containing tar are continuously removed from the extractor. The overflow stream had an average concentration of 215 parts methyl iodide, 14 parts methyl acetate, 379 parts water, 438 parts acetic acid, 55 parts lithium iodide, 58 parts HI, 5.3 parts Rh and 31 parts. Contains iodine. The extractor underflow stream contains an average concentration, 802 parts methyl iodide, 3 parts methyl acetate, 7 parts EDA, 6 parts iodine, 0.2 parts Rh and 74 parts tar.

  The rhodium extraction efficiency of this system can be described as the amount of rhodium in the underflow stream divided by the total amount of rhodium in the underflow and overflow streams (ie, the total discharge of the system). This amount is 5.3 ÷ (5.3 + 0.2) = 0.96, ie 96%.

Example B
A process similar to Comparative Example 1 was operated. The catalyst-tar solution was 52 parts methyl iodide, 2 parts acetone, 219 parts methyl acetate, 335 parts acetic acid, 647 parts Ac ₂ O, 3 parts EDA, 11 parts lithium iodide, 21 parts Lithium acetate, 4.3 parts Rh and 73 parts tar were included. The filtered stream from the stripped tar receiver fed to the extraction column has an average concentration of 990 parts methyl iodide, 1 part acetone, 25 parts methyl acetate, 148 parts water, 435 parts acetic acid, 4 parts EDA, 68 parts lithium iodide, 45 parts elemental iodine, 91 parts tar and 6.3 parts Rh. A stream containing an average concentration of 239 parts methyl iodide, 1 part methyl acetate and 0.2 parts water is fed to the upper part of the extractor. Model the stream taken from the midpoint of the continuous extractor and average concentration, 84 parts methyl iodide, 3 parts methyl acetate, 197 parts water, 20 parts acetic acid, 1 part EDA, 20 parts iodide. Lithium, 11 parts HI (100% hydrogen iodide), 13 parts iodine and 18 parts tar. An aqueous solution containing an average concentration, 252 parts water, 123 parts acetic acid, 57 parts HI and 1 part iodine is fed to the lower part of the extractor.

The extractor overflow stream was 361 parts methyl iodide, 220 parts water, 686 parts acetic acid, 68 parts lithium iodide, 71 parts HI, 30 parts iodine, 13 parts tar, and 5.1 parts Rh. including. The extractor underflow stream contained 694 parts methyl iodide, 1 part methyl acetate, 10 parts acetic acid, 4 parts EDA, 0.1 part Rh, 1 part iodine and 47 parts tar.
The rhodium extraction efficiency of this system is 5.1 ÷ (5.1 + 0.1) = 0.98, ie 98%.

Laboratory extraction: Examples 1-38
Examples 1-17
A non-aqueous (methyl iodide) underflow from an extraction process similar to that described in Comparative Example A was obtained. The tar stream obtained from the organic phase underflow was 91.9% methyl iodide, 6.8% tar, 52 ppm Rh, 0.5% I ₂ , 0.4% methyl acetate, 0.1% % EDA and 0.04% acetic acid.

  This tar stream (40 mL) was sent to 4 batch extractions with a mixture of HI, acetic acid and water (40 mL each). The mixture was shaken in a separatory funnel for 2 minutes and the layers were allowed to separate for at least 2 minutes. The bottom layer was contacted with a fresh aqueous mixture for subsequent extraction. This was repeated and a total of four extractions were performed on the bottom (organic) layer. Each top layer was collected and sampled. A portion of the bottom layer (5 mL) was collected and sampled only after the first extraction. Samples were analyzed for rhodium and tar concentrations.

  The mass balance ranged from 97.6 to 98.5% in 17 experiments. The rhodium balance was in the range of 65-108%. The mass balance for tar was in the range of 66-86%. Rhodium extraction was calculated as the cumulative amount of rhodium measured in the aqueous layer compared to the initially measured amount of rhodium in the tar stream. The tar extraction in the aqueous stream was calculated similarly. Seventeen experiments were designed to measure the effect of HI, acetic acid and water concentrations on rhodium and tar extraction. The HI concentration was varied from 5 to 20%. The acetic acid concentration was varied from 0 to 60%. The water concentration was varied from 20 to 95%. Rhodium extraction ranged from 6 to 72%. Tar extraction was in the range of 1-27%.

  Table 1A shows the composition of the aqueous stream only used in these examples. Table 1B shows the total composition of the aqueous and organic phases of each extraction and the rhodium and tar extraction efficiency. The weight percentages in Table 1B are adjusted to show a tar solution concentration of 3% and a methyl iodide concentration of 63%.

  The data show that acetic acid increases rhodium extraction regardless of HI concentration. The same is true for tar extraction, but to a lesser extent. Comparison between Example 1 and Example 2 and Example 3 and Example 5, Comparison between Example 8 and Example 9, Comparison between Example 10 and Example 11, and Comparison between Example 12 and Example 13 with Example 14 and Example 17 Shows the advantages of acetic acid.

Examples 18-29
A separate but similar experiment used tar streams obtained from two tar treatments through two rhodium extraction column processes operating efficiently in series. Each extraction process was operated in the same manner as shown in Comparative Example A above, but the organic phase underflow from the first extraction process was fed to a stirred tank where it was fed to the second extraction. Held on. Nothing else was fed to the stirred tank, so the main feed to the second extraction had the same composition as the underflow from the first column extraction. The aqueous HI and methyl iodide feed to the second extraction was identical to the first. The second column underflow was 94.0% methyl iodide, 5.0% tar, 27 ppm Rh, 0.5% I ₂ , 0.1% methyl acetate and 0.1% EDA. Had a composition.

  This underflow stream (30 mL) was sent to batch extraction four times with a mixture of HI, acetic acid and water (40 mL each). The mixture was shaken in a separatory funnel for 2 minutes and the layers were allowed to separate for at least 2 minutes. The bottom layer was contacted with a fresh aqueous mixture for subsequent extraction. This was repeated and a total of four extractions were performed on the bottom (organic) layer. Each top layer was collected and sampled. Samples were analyzed for rhodium and tar concentrations.

  The mass balance ranged from 96.3 to 98.6% in 12 experiments. The rhodium mass balance ranged from 64 to 137%. The mass balance of tar was in the range of 61-90%. Rhodium extraction was calculated as the cumulative amount of rhodium recovered in the aqueous layer compared to the amount of rhodium present in the tar stream. The tar extraction in the aqueous stream was calculated similarly. Twelve experiments were designed to measure the effect of HI, acetic acid and water concentrations on rhodium and tar extraction. The HI concentration was varied from 5 to 20%. The acetic acid concentration was varied from 0 to 70%. The water concentration was varied from 10 to 95%. Rhodium extraction ranged from 0 to 105%. Tar extraction ranged from 2 to 49%.

  Table 2A shows the composition of the aqueous stream only used in these examples. Table 2B shows the total composition of the aqueous and organic phases of each extraction and the rhodium and tar extraction efficiency. The mass% in Table 2B is adjusted to show a tar solution concentration of 3% and a methyl iodide concentration of 57%.

  The data show that the addition of acetic acid increased rhodium extraction, regardless of HI concentration, even after taring two runs through a continuous extractor process with HI feed. The same is true for tar extraction, but to a lesser extent. Comparing Examples 18-22 to each other, acetic acid is advantageous at high concentrations (70% in Table 2A, 28% in Table 2B) when the HI concentration is low (5% in Table 2A, 2% in Table 2B) It shows that. Comparing Examples 26-30 to each other, acetic acid is again advantageous only at high concentrations, but the threshold drops when the HI concentration is high (20% in Table 2A, 8% in Table 2B). (Specifically, 35% or more in Table 2A and 14% or more in Table 2B).

  Comparison of Example 18 and Example 26 shows that rhodium is essentially unextractable in the absence of acetic acid, regardless of the concentration of HI, in these streams that had previously undergone two HI extractions. Comparison between Example 20 and Example 28 and Example 22 and Example 23 show the advantage of HI when acetic acid is present. The HI concentration is effective for tar extraction only at a very high acetic acid concentration.

  A high concentration of acetic acid results in a weight loss of the organic layer. Although the effect was not evident when the acetic acid concentration was 35% or less (Table 2A), when the acetic acid concentration exceeded 35% (Table 2A), the mass of the organic layer significantly decreased after 4 extractions.

  FIG. 1 graphically illustrates this data, showing the importance of both HI and acetic acid concentrations. As can be seen, increasing the acetic acid concentration (x-axis) increases the rhodium extraction efficiency (y-axis). However, the increase occurs more rapidly with acetic acid concentration, with higher HI concentrations (square data points) higher than lower HI concentrations (diamond-shaped data points) and more rapidly at lower acetic acid concentrations. This rapid increase compares the data in Table 2B for all samples with 8% HI (Examples 26-29), or the data for all samples with 6% HI (Examples 24-25). It can be easily understood by comparing.

Examples 30-38
The stream recovered from the methyl acetate carbonylation reactor was distilled at 95 ° C. and 7 torr absolute pressure. The concentrated sample was diluted with acetic acid and methyl iodide and contained 78.7% methyl iodide, 15.6% acetic acid, 5.6% tar and 713 ppm Rh.

  This tar stream (100 g) was sent to up to four batch extractions with a mixture of HI, acetic acid and water (100 g each). The mixture was shaken in a separatory funnel for 2 minutes and the layers were allowed to separate for at least 2 minutes. The bottom layer was collected. The top layer was collected and sampled. With the fresh portion of the same extractant, the bottom layer was returned to the separatory funnel for subsequent extraction. A portion of the bottom layer (5 mL) was collected after each extraction and sampled to adjust the amount of extractant. Samples were analyzed for rhodium and tar concentrations.

  The mass balance ranged from 95.9 to 98.1% in 9 experiments. The rhodium balance was in the range of 45-96%. Tar balance was in the range of 30-44%. Rhodium extraction was calculated as the cumulative amount of rhodium recovered in the aqueous layer compared to the amount of rhodium present in the tar stream. Tar extraction was calculated similarly. Nine experiments were designed to measure the effect of HI, acetic acid and water concentrations on rhodium and tar extraction. The HI concentration was varied from 0-15%. The acetic acid concentration was varied from 0 to 75%. The water concentration was varied from 25 to 100%. Rhodium extraction ranged from 13 to 96%. Tar extraction after the first extraction was in the range of 2-11%. Tar extraction was not measured after the first extraction.

  Table 3A shows the composition of the aqueous stream only used in these examples. Table 3B shows the total composition of the aqueous and organic phases of each extraction and the rhodium and tar extraction efficiency. The mass% in Table 3B is adjusted to show a tar solution concentration of 3% and a methyl iodide concentration of 39%. All samples are based on a series of 4 extractions, except Table 3B indicates otherwise.

  The data show that addition of acetic acid to HI increases rhodium extraction regardless of HI concentration. The same is true for tar extraction, but to a lesser extent. Comparison of Examples 30-32 with each other and Examples 33-38 with each other show the benefit of acetic acid. A comparison between Example 30 and Example 33, a comparison between Example 31 and Example 35, and a comparison between Example 32 and Example 37 show the benefit of HI. The combination of HI and acetic acid in the aqueous stream is extremely powerful for rhodium extraction.

  FIG. 2 graphically illustrates the data in Table 3B, again showing the separate effects of HI and acetic acid concentrations. As can be seen, as the acetic acid concentration (x-axis) increases, the rhodium extraction efficiency (y-axis) results in a sample without HI (diamond-shaped data points) and a sample with 8% HI (square data points). Increase in both. As shown, the extraction efficiency at 38% acetic acid concentration without HI is 84%, which is the same as the extraction efficiency with 8% acetic acid in 8% HI (compare Examples 30 and 37 in Table 3B). I want to be) The extraction of Example 38 with an acetic acid concentration of 45% results in miscibility of the aqueous and organic phases to the extent that an insufficient organic phase remains after three extractions, resulting in the highest undesired tar concentration in the aqueous phase. It was. These things indicate that the use of HI and acetic acid together at lower concentrations (not higher concentrations of acetic acid) results in efficient rhodium extraction without drawing excess tar into the recovered aqueous phase. Shows the advantage of making it possible.

  Although the invention has been described in detail with particular reference to preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims (20)

A method for recovering a catalyst from a liquid containing catalyst and tar, said liquid containing catalyst and tar comprising at least one aqueous solution containing acetic acid and hydrogen iodide and methyl iodide, and acetic acid and hydrogen iodide. Combining under conditions effective to cause the formation of an aqueous phase comprising and an organic phase comprising methyl iodide, wherein at least a portion of the catalyst is concentrated in the aqueous phase, the method further comprising:
Feeding said liquid comprising catalyst and tar to a main feed position on the container;
Feeding said at least one aqueous solution comprising hydrogen iodide and acetic acid to at least one aqueous feed location on said container, wherein said aqueous feed location is vertically below said primary feed location;
Recovering at least a portion of the organic phase from the vessel at an organic phase recovery position, wherein the organic phase recovery position is vertically below the main feed position; and
Recovering at least a portion of the aqueous phase from the vessel at an aqueous phase recovery position, wherein the aqueous phase recovery position is vertically above the main feed position;
Including a method.   Feeding at least one liquid stream comprising methyl iodide to at least one organic feed location on the vessel, wherein the at least one organic feed location is vertically above the main feed location. The method according to 1. A method for recovering a catalyst from a liquid containing catalyst and tar, said liquid containing catalyst and tar in the presence of hydrogen iodide and methyl iodide, at least one aqueous solution containing acetic acid, acetic acid and Combining under conditions effective to cause the formation of an aqueous phase comprising hydrogen iodide and an organic phase comprising methyl iodide, wherein at least a portion of the catalyst is concentrated in the aqueous phase, The method is further
Feeding said liquid comprising catalyst and tar to a main feed position on the container;
Feeding at least one liquid stream comprising methyl iodide to at least one organic feed location on the vessel, wherein the at least one organic feed location is vertically above the primary feed location;
Feeding said at least one aqueous solution comprising acetic acid to at least one aqueous feed location on said container, wherein said aqueous feed location is vertically below said primary feed location;
Recovering at least a portion of the organic phase from the vessel at an organic phase recovery position, wherein the organic phase recovery position is vertically below the main feed position; and
Recovering at least a portion of the aqueous phase from the vessel at an aqueous phase recovery position, wherein the aqueous phase recovery position is vertically above the main feed position;
Including a method.   The method of claim 3, wherein the aqueous stream further comprises hydrogen iodide.   The method according to claim 1, wherein the liquid containing catalyst and tar further comprises methyl iodide.   The method according to any one of claims 1 to 5, wherein the liquid containing catalyst and tar further comprises acetic acid.   The method according to claim 1, wherein the liquid containing catalyst and tar further comprises hydrogen iodide.   The method according to claim 1, wherein the combining is performed in the presence of elemental iodine.   The method of claim 8, wherein the liquid comprising catalyst and tar comprises at least a portion of the elemental iodine.   10. The at least one aqueous solution comprising acetic acid comprises a first solution containing hydrogen iodide but not containing acetic acid and a second solution containing acetic acid but no hydrogen iodide. The method according to claim 1. The method of any one of claims 1 to 9 , wherein the at least one aqueous solution comprising acetic acid comprises at least one single solution comprising both hydrogen iodide and acetic acid.   12. A process according to any one of the preceding claims, wherein the catalyst comprises at least one Group VIII metal.   13. The method of claim 12, wherein the at least one Group VIII metal is rhodium.   14. A method according to any one of the preceding claims, wherein the at least one aqueous phase recovery location is vertically above the at least one organic feed location.   15. A method according to any one of the preceding claims, wherein the at least one organic phase recovery location is vertically below the at least one aqueous feed location.   The container includes an upper vertical tri-section, a middle vertical tri-section, and a lower vertical tri-section, and the at least one aqueous feed position is in the lower vertical tri-section of the container. The method of any one of -15.   The container includes an upper vertical bisector, a middle vertical halves and a lower vertical halves, and the at least one organic feed location is in the upper vertical halves of the container. The method of any one of -16.   18. A method according to any one of the preceding claims, wherein the container comprises a column and the column comprises at least one reciprocating plate agitator.   The method according to any one of claims 1 to 18, wherein 22.5 to 55 mass% of all materials fed to the container is acetic acid.   The method according to any one of claims 1 to 19, wherein 0.5 to 10% by mass of all materials fed to the vessel is hydrogen iodide.

Images