Process for treating zeolite catalysts
View Patent ↗Process for treating a zeolite catalyst for the carbonylation of dimethyl ether to produce methyl acetate, in which the catalyst is contacted with a treatment gas containing water vapor in an amount of at least 1 mol % and at a temperature below which dealumination of the zeolite structure occurs. The zeolite contains at least one channel which is defined by an 8-member ring and is mordenite.
1. A process for treating a zeolite catalyst for the carbonylation of dimethyl ether to produce methyl acetate wherein the catalyst is contacted with a treatment gas comprising water vapour in an amount of at least 1 mol % and at a temperature below which dealumination of the zeolite structure occurs and wherein the zeolite contains at least one channel which is defined by an 8-member ring and is mordenite.
2. A carbonylation process comprised of contacting dimethyl ether with carbon monoxide in the presence of a zeolite catalyst to produce methyl acetate reaction product, wherein the catalyst has been treated by contacting it with a treatment gas comprising water vapour in an amount of at least 1 mol % and at a temperature below which dealumination of the zeolite structure occurs and wherein the zeolite contains at least one channel which is defined by an 8-member ring and is mordenite.
3. A process for the production of methyl acetate by the carbonylation of dimethyl ether with carbon monoxide in the presence of a treated zeolite catalyst wherein the process comprises the steps
(i) contacting a zeolite catalyst with a treatment gas comprising water vapour in an amount of at least 1 mol % and at a temperature below which dealumination of the zeolite structure occurs and wherein the zeolite contains at least one channel which is defined by an 8-member ring and is mordenite; and
(ii) ceasing contact of the catalyst with the water vapour; and
(iii) contacting the treated catalyst with dimethyl ether and carbon monoxide to produce methyl acetate reaction product.
4. A process according to claim 1 wherein the mordenite is in the hydrogen form.
5. A process according to claim 1 wherein the zeolite in addition to silicon and aluminium comprises a trivalent framework modifier element selected from one or more of boron, gallium and iron.
6. A process according to claim 1 wherein the catalyst is in the form of a composite comprising the zeolite and an inorganic oxide binder selected from aluminas, silica-aluminas and silicas.
7. A process according to claim 1 wherein the catalyst is contacted with the treatment gas at a temperature of from 200° C. to 350° C.
8. A process according to claim 7 wherein the temperature is from 250 C to 310° C.
9. A process according to claim 8 wherein the temperature is from 285° C. to 300° C.
10. A process according to claim 1 wherein the treatment gas comprises from 1 to 10 mol % water vapour.
11. A process according to claim 10 wherein the treatment gas comprises from 2 to 10 mol % water vapour.
12. A process according to claim 1 wherein the treatment gas further comprises at least one component selected from one or more of carbon monoxide, hydrogen and dimethyl ether.
13. A process according to claim 1 wherein the treatment gas further comprises synthesis gas.
14. A process according to claim 13 wherein the synthesis gas has a molar ratio of carbon monoxide to hydrogen of from 15:1 to 1:3.
15. A process according to claim 14 wherein the molar ratio is 4:1 to 1:1.
16. A process according to claim 1 wherein the catalyst is contacted with the treatment gas for a period of from 10 minutes to 24 hours.
17. A process according to claim 1 wherein the catalyst is contacted with the treatment gas at a pressure in the range of from 10 to 100 barg.
18. A process according to claim 1 wherein the catalyst is contacted with the treatment gas at a gas hourly space velocity in the range 3000 to 10,000 h- 1 .
19. A process according to claim 3 wherein dimethyl ether is added to a treatment gas subsequent to commencing contact of the catalyst with the treatment gas but prior to ceasing contact of the catalyst with the water vapour.
20. A process according to claim 19 wherein dimethyl ether is added to the treatment gas for up to 1 minute to 1 hour prior to ceasing contact of the catalyst with water vapour.
21. A process according to claim 19 wherein dimethyl ether is added to the treatment gas at a concentration in the range 0.1 to 20 mol % based on the total components of the treatment gas.
22. A process according to claim 21 wherein the dimethyl concentration is in the range 1.5 to 5 mol % based on the total components of the treatment gas.
23. A process according to claim 3 wherein in step (iii) a synthesis gas is employed as the source of carbon monoxide.
24. A process according to claim 3 wherein step (iii) is carried out at a temperature of from 250° C. to 350° C. and at a total pressure of from 10 to 100 barg.
25. A process according to claim 3 wherein methyl acetate is recovered from the reaction product and some or all of the recovered methyl acetate is converted to acetic acid.