# US 8,785,684 B2 · Methanol carbonylation process with rhodium catalyst, an iodide salt and a metallic co-catalyst selected from transition metals, indium, strontium, barium, zinc, tin and heteropoly acids > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,785,684 B2 - Document ID: US8785684B2 - Status: Granted - Kind: B2 - Application number: 13/693,633 - Filed: 2012-12-04 - Published: 2013-04-25 - Granted: 2014-07-22 - Earliest claimed: 2010-06-14 - Assignees: Celanese International Corporation - Applicants: Celanese International Corporation - Inventors: Carole M. Le Berre; Samuel Gautron; Philippe J. Kalck; Philippe G. Serp; Nicolas D. Lassauque; G. Paull Torrence - Web page: https://patentgrep.com/patent/US8785684B2 ## CPC - C07C 51/12: on an oxygen-containing group in organic compounds, e.g. alcohols - C07C 51/47: by solid-liquid treatment; by chemisorption - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS ## Abstract A carbonylation process for making acetic acid uses a metallic co-catalyst composition effective as a rhodium stabilizer and rate promoter at molar ratios of metal/rhodium of from about 0.5 to 30. A preferred process includes: (a) reacting methanol with a carbon monoxide feedstock in a rhodium-based catalytic reaction mixture having: (i) a rhodium catalyst metal, (ii) methyl iodide maintained from about 1 to 20 weight percent, (iii) a lithium iodide co-catalyst, (iv) a metallic co-catalyst composition, (v) water maintained from 0.1 weight percent to less than 8 weight percent, (vi) methyl acetate maintained from about 0.5 to about 30 weight percent, and (vii) acetic acid; (b) flashing crude acetic acid from the reaction mixture; and (c) purifying the crude acetic acid. This process achieves stability and a STY greater than 10 mol/L/hr, with substantially less than a theoretically equivalent inorganic iodide content corresponding to the metallic co-catalyst and lithium iodide. ## Claims ### Claim 1 A continuous process for the production of acetic acid comprising: (a) reacting a compound, selected from the group consisting of methanol and reactive derivatives thereof, with carbon monoxide to produce acetic acid in an aqueous reaction mixture, the reaction being carried out while maintaining a concentration of water in the reaction mixture of from 0.1 wt % up to about 8 wt %, the reaction also being carried out in the presence of a homogeneous rhodium-based catalyst system comprising: (i) a rhodium catalyst metal; (ii) an iodide promoter; (iii) an inorganic iodide-providing co-catalyst at a molar ratio of inorganic iodide-providing co-catalyst:Rh of less than 76:1; and (iv) a metallic co-stabilizing or rate-promoting composition including a metal selected from the group consisting of transition metals, indium, strontium, barium, zinc, tin, HPA, and mixtures thereof; and (b) recovering acetic acid from the reaction mixture; wherein the inorganic iodide-providing co-catalyst and the metal of the metallic co-stabilizing or rate-promoting composition are present in a molar ratio of 15:1 to 0.6:1 and wherein further the reaction mixture contains less than 70% of a theoretical amount of inorganic iodide equivalent to the presence of both the metal of the metallic co-stabilizing or rate-promoting composition and the inorganic iodide-providing co-catalyst. ### Claim 2 (depends on 1) The process according to claim 1, wherein the process is operated with a total inorganic iodide content in the reaction mixture of less than 5 weight %. ### Claim 3 (depends on 1) The process according to claim 1, wherein the inorganic iodide-providing co-catalyst is lithium iodide present in a lithium iodide:rhodium molar ratio of about 1:1 up to a ratio of about 50:1. ### Claim 4 (depends on 1) The process according to claim 1, wherein the process is further characterized by a STY greater than 10 moles/L/hr. ### Claim 5 (depends on 1) The process according to claim 1, wherein the iodide promoter is methyl iodide maintained in said reaction mixture in a concentration of from about 1 to about 20 weight percent. ### Claim 6 (depends on 1) The process according to claim 1, wherein the process is operated with a total inorganic iodide content in the reaction mixture of less than 4.5 weight % and the water content of the reaction mixture is maintained at a level of less than or equal to 5 weight %. ### Claim 7 (depends on 1) The process according to claim 1, wherein the metallic co-stabilizing or rate-promoting composition comprises a single metal compound. ### Claim 8 (depends on 1) The process according to claim 1, wherein the metallic co-stabilizing or rate-promoting composition comprises two metal components. ### Claim 9 (depends on 1) The process according to claim 1, wherein the reaction mixture contains from 250 ppm rhodium to 3000 ppm rhodium. ### Claim 10 (depends on 1) The process according to claim 1, wherein: the aqueous reaction mixture is disposed in a pressurized reactor, and wherein the homogeneous rhodium-based aqueous catalyst system further comprises (v) methyl acetate maintained in said reaction mixture in a concentration of from about 0.5 to about 30 weight percent; and (vi) acetic acid; and wherein further the step of recovering acetic acid comprises providing a stream of the reaction mixture to a flash vessel; flashing crude acetic acid product from the reaction mixture to generate a crude product stream including acetic acid, methyl acetate, methyl iodide and water; and purifying the crude product stream to remove methyl acetate, methyl iodide and water therefrom, to obtain a purified acetic acid product. ### Claim 11 (depends on 10) The process according to claim 10, wherein the process is further characterized by a propionic acid concentration of less than 50 parts per million as measured at the flash vessel overhead. ### Claim 12 (depends on 10) The process according to claim 10, wherein a partial pressure of carbon monoxide is maintained above 1 bar in the pressurized reactor. ### Claim 13 (depends on 10) The process according to claim 10, wherein a partial pressure of carbon monoxide is maintained below 1 bar in the flash vessel. ### Claim 14 (depends on 1) The process according to claim 1, wherein: the inorganic iodide-providing co-catalyst is provided at a molar ratio of inorganic iodide-providing co-catalyst:Rh of less than 70:1; and the metallic co-stabilizing or rate-promoting composition is present in a metal to rhodium molar ratio of at least 0.5:1 and up to 20:1. ### Claim 15 (depends on 1) The process according to claim 1, wherein the water content of the reaction mixture is maintained at a level of from 0.2 weight % to 5 weight %.