Process for the continuous production of methylmercaptan

1. Process for the continuous catalyzed production of methylmercaptan comprising reacting methanol and hydrogen sulphide in the presence of a catalyst therefor in a gas phase at a temperature of 200 to 600° C. and a pressure of 1.5 to 40 bar, in a plurality of zones

a) distributing the total amount of the catalyst to at least two zones which are separate from one another, in such a way that the amount of catalyst increases in the flow direction,

b) supplying a first of said zones with a gaseous mixture comprising methanol and hydrogen sulphide,

c) feeding methanol and hydrogen sulphide between the first, the second and optionally the further zones in a liquid and/or gaseous form, and

d) separating off methylmercaptan formed thereby,

e) the total molar ratio of the amounts of hydrogen sulphide and methanol employed amounting to 1.1:1 to 10:1.

2. The process according to claim 1 , wherein said molar ratio is 1.1:1 to 5:1.

3. The process according to claim 1 , wherein said reacting is in a grid reactor having 2 to 25 catalyst beds.

4. The process according to claim 3 , wherein the reactor has 3 to 10 catalyst beds.

5. The process according to claim 1 , wherein catalyst packings in the zones are covered with a layer of packings of inert materials.

6. The process according to claim 5 , wherein the first catalyst zone in the flow direction and optionally the last zone are completely or partly coated with an inert material.

7. The process according to claim 1 , wherein at least two different catalysts are employed in the zones.

8. The process according to claim 1 , wherein the amount of catalyst between the zones varies.

9. The process according to claim 1 , wherein the total amount of hydrogen sulphide employed is employed as a gaseous mixture of methanol and hydrogen sulphide.

10. The process according to claim 1 , wherein hydrogen sulphide or starting gas is fed into the intermediate space between one or more of the first and second or further zones.

11. The process according to claim 1 , wherein the molar ratio of hydrogen sulphide to methanol in the starting gas is 1.1:1 to 20:1.

12. The process according to claim 1 , wherein the molar ratio of hydrogen sulphide to methanol in the starting gas is 1.1:1 to 10:1.

13. The process according to claim 1 , wherein the molar ratio of hydrogen sulphide to methanol in the starting gas is 3:1 to 10:1.

14. Process according to claim 1 , further comprising feeding the methanol into intermediate spaces between the zones in equal amounts.

15. The process according to claim 1 , further comprising feeding the methanol into intermediate spaces between the zones in unequal amounts.

16. The process according to claim 1 , wherein the last catalyst-containing zone is not supplied with methanol.

17. The process according to claim 2 , further comprising flowing methanol and hydrogen sulphide through the catalyst beds in variable directions.

18. The process according to claim 1 , further comprising using as catalyst alkali metal tungstates or halide-containing alkali metal tungstates.

19. The process according to claim 18 , wherein the catalyst is a halide-free or halide-containing caesium tungstate.

20. The process according to claim 1 , further comprising providing a turbulent flow and a uniform distribution and mixing of reactants by means of inert packing materials and/or devices to thereby completely mix the methanol and hydrogen sulphide between the zones.

21. The process according to claim 1 , wherein catalyst grids are designed as catalyst beds having radial, square or polygonal geometry and the grids can be individually filled with catalyst or emptied, their design optionally being such that they can be removed from the reactor in modular form.

22. The process according to claim 1 , wherein at least one detachable or undetachable connection or opening in the reactor wall is utilized for the simple exchange of the catalyst in the individual grids.