Process for the preparation of alkyl mercaptans

Patent metadata

Field	Value
Publication number	US-9809535-B2
Application number	US-201514974625-A
Country	US
Kind code	B2
Filing date	Dec 18, 2015
Priority date	Dec 19, 2014
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

An alkyl mercaptan is prepared by reacting an aliphatic alcohol with hydrogen sulfide in the presence of a heterogeneous catalyst at varying temperatures.

First claim

The invention claimed is:

1. A process for preparing an alkyl mercaptan, the process comprising:
reacting an aliphatic alcohol with hydrogen sulfide in the presence of a heterogeneous catalyst, and
a) starting the preparation of the alkyl mercaptan at a temperature T 1 and preparing the alkyl mercaptan at the temperature T 1 for a time period t 1 , and
b) performing temperature cycles of the number n, comprising
b1) increasing the reaction temperature to a temperature T 2 and preparing the alkyl mercaptan at the temperature T 2 for a time period t 2 , followed by
b2) decreasing the reaction temperature from the temperature T 2 to a temperature T 3 and preparing the alkyl mercaptan at the temperature T 3 for a time period t 3 ,

wherein
the temperature T 2 is always higher than the temperatures T 1 and T 3 ,
and
n is an integer larger than zero.

2. The process according to claim 1 , wherein the temperature T 1 and the temperature T 3 independently from each other range from 250° C.+/−10° C. to 350° C.+/−10° C.

3. The process according to claim 1 , wherein the temperature T 2 is at least 5° C. higher than each of the temperatures T 1 and T 3 .

4. The process according to claim 1 , wherein the temperature T 3 of a temperature cycle of the number n has an equal or a different value compared to the temperature T 3 in the preceding temperature cycle of the number n−1.

5. The process according to claim 1 , wherein the temperature T 2 in a temperature cycle of the number n has the same value as the temperature T 2 in the preceding temperature cycle of the number n−1.

6. The process according to claim 1 , wherein the temperature T 2 in a temperature cycle of the number n has a higher value than the temperature T 2 in the preceding temperature cycle of the number n−1.

7. The process according to claim 1 , wherein the time period t 1 ranges from 1 hour+/−10% to a month.

8. The process according to claim 7 , wherein the time period t 2 ranges from 1 hour+/−10% to 50 hours+/−10%.

9. The process according to claim 1 , wherein the time period t 3 is until the recharging of the reactor with a new catalyst.

10. The process according to claim 9 , wherein the time period t 3 is up to a month.

11. The process according to claim 1 , wherein an aluminum oxide-based catalyst containing an alkali tungstate is used.

12. The process according to claim 11 , wherein the catalyst contains a cesium tungstate.

13. The process according to claim 1 , wherein the catalyst is sulfidized prior to its use in the preparation of alkyl mercaptans.

14. The process according to claim 1 , wherein the aliphatic alcohol is a C 1 -C 3 alcohol.

15. The process according to claim 14 , wherein the aliphatic alcohol is methanol, ethanol, n-propanol, iso-propanol or tert-butanol.

16. The process according to claim 1 , wherein methyl mercaptan is prepared from methanol and hydrogen sulphide over an aluminum oxide-based catalyst containing cesium tungstate as promoter.

17. The process according to claim 2 , wherein the temperature T 2 is at least 5° C. higher than each of the temperatures T 1 and T 3 .

18. The process according to claim 2 , wherein the temperature T 3 of a temperature cycle of the number n has an equal or a different value compared to the temperature T 3 in the preceding temperature cycle of the number n−1.

19. The process according to claim 2 , wherein the temperature T 2 in a temperature cycle of the number n has the same value as the temperature T 2 in the preceding temperature cycle of the number n−1.

20. The process according to claim 2 , wherein the temperature T 2 in a temperature cycle of the number n has a higher value than the temperature T 2 in the preceding temperature cycle of the number n−1.

Assignees

• Fonfe Benjamin
• Kretz Stephan
• Jakob Harald
• Evonik Degussa Gmbh

Inventors

• Fonfe Benjamin
• Kretz Stephan
• Jakob Harald

Classifications

• B01J2231/4294

  using S nucleophiles, e.g. thiols · CPC title

• C07C319/02 Primary

  of thiols · CPC title

• C07C319/08 Primary

  by replacement of hydroxy groups or etherified or esterified hydroxy groups · CPC title

• C07B45/06

  of mercapto or sulfide groups · CPC title

• B01J31/34

  of chromium, molybdenum or tungsten · CPC title