# US 9,873,114 B2 · Post-gilding of PD-AU-coated shell catalysts > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,873,114 B2 - Document ID: US9873114B2 - Status: Granted - Kind: B2 - Application number: 14/379,262 - Filed: 2013-02-19 - Published: 2015-01-29 - Granted: 2018-01-23 - Earliest claimed: 2012-02-20 - Assignees: Clariant Produkte (Deutschland) GmbH - Applicants: Gerhard Mestl; Peter Scheck; Alfred Hagemeyer; Carolin Fischer; Roman Bobka - Inventors: Gerhard Mestl; Peter Scheck; Alfred Hagemeyer; Carolin Fischer; Roman Bobka - Web page: https://patentgrep.com/patent/US9873114B2 ## CPC - B01J 31/28: of the platinum group metals, iron group metals or copper - B01J 23/52: Gold - B01J 23/58: with alkali- or alkaline earth metals - B01J 31/38: of titanium, zirconium or hafnium - B01J 35/397: {Egg shell like} - B01J 37/0205: {in several steps} - B01J 37/18: with gases containing free hydrogen - C07C 67/05: with oxidation - C07C 67/055: in the presence of platinum group metals or their compounds - B01J 2231/49: Esterification or transesterification - B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS ## Abstract The invention relates to a method for producing a shell catalyst that is suitable for producing vinyl acetate monomer (VAM). The invention further relates to a shell catalyst that is obtainable by the method according to the invention and to the use of the shell catalyst according to the invention for producing VAM. ## Claims ### Claim 1 A process for producing an eggshell catalyst, comprising the steps of: (a) subjecting a bed of a catalyst support body to a circulating motion; (b) contacting an atomized aqueous solution comprising a Pd-containing precursor compound and an Au-containing precursor compound with the bed of the catalyst support body subjected to the circulating motion by spraying; (c) contacting an atomized aqueous solution comprising an Au-containing precursor compound with the catalyst support body obtained after step (b); and (d) metal reduction by subjecting the catalyst support body obtained in step (c) to a thermal treatment in a nonoxidizing atmosphere and wherein the Au-containing precursor compounds in steps (b) and (c) are, independently, compounds selected from the group consisting of hydroxidic metalate compounds. ### Claim 2 (depends on 1) The process as claimed in claim 1, wherein the contacting in step (c) includes spraying the solution onto a bed of the catalyst support body subjected to a circulating motion. ### Claim 3 (depends on 2) The process as claimed in claim 2, wherein the circulating motions are conducted with the aid of a process gas. ### Claim 4 (depends on 2) The process as claimed in claim 2, wherein the circulating motions take place in a moving bed or fluidized bed. ### Claim 5 (depends on 1) The process as claimed in claim 1 wherein the thermal treatment is conducted within a range from 40° C. to 500° C. ### Claim 6 (depends on 1) The process as claimed in claim 1, wherein the ratio of the weight of the solution sprayed on in step (b) or (c) to the weight of the bed of the catalyst support body is within the range from 0.005 to 0.1. ### Claim 7 (depends on 1) The process as claimed in claim 1, wherein the catalyst support body after step (b) has a Pd content in the range from 0.5 to 2.5% by weight, based on the total weight of the catalyst support body. ### Claim 8 (depends on 1) The process as claimed in claim 1, wherein the catalyst support body after step (b) has an Au content in the range from 0.2 to 1.0% by weight, based on the total weight of the catalyst support body. ### Claim 9 (depends on 1) The process as claimed in claim 1, wherein the eggshell catalyst has an Au content in the range from 0.25 to 1.2% by weight, based on the total weight of the eggshell catalyst. ### Claim 10 (depends on 1) The process as claimed in claim 1, wherein the Pd-containing precursor compound is a compound selected from the group consisting of a nitrate compound, nitrite compound, acetate compound, tetraammine compound, diammine compound, hydrogencarbonate compound, hydroxidic metalate compounds and mixtures thereof. ### Claim 11 (depends on 1) The process as claimed in claim 1, wherein the nonoxidizing atmosphere comprises a reducing agent. ### Claim 12 (depends on 11) The process as claimed in claim 11, wherein the reducing agent is hydrogen. ### Claim 13 (depends on 1) The process as claimed in claim 1, wherein the support body is impregnated with KOAc (potassium acetate) after the thermal treatment. ### Claim 14 A process for producing an eggshell catalyst, comprising the steps of: (a) subjecting a bed of a catalyst support body to a circulating motion; (b) contacting an atomized aqueous solution comprising a Pd-containing precursor compound and an Au-containing precursor compound with the bed of the catalyst support body subjected to the circulating motion by spraying; (c) contacting an atomized aqueous solution comprising an Au-containing precursor compound with the catalyst support body obtained after step (b); and (d) metal reduction by subjecting the catalyst support body obtained in step (c) to a thermal treatment in a nonoxidizing atmosphere and wherein the Au-containing precursor compounds in steps (b) and (c) are, independently, NaAuO2, KAuO2, LiAuO2 or RbAuO2.