Thioetherification of mercaptanes in C4 hydrocarbon mixtures
View Patent ↗The invention relates to a method for the thioetherification of mercaptanes with polyunsaturated hydrocarbons, carried out in a reactor with the addition of hydrogen, using a heterogenic catalyst and in the presence of 1-butene. The aim of the invention is to develop such a method to the extent that the creation of value from the C 4 raw material stream is increased. Said aim is achieved in that the hydrogen is added to the reaction in such a manner that the molar ratio of hydrogen to polyunsaturated hydrocarbons is no more than one.
1. A process for removing mercaptans from a C4 hydrocarbon mixture, the C4 hydrocarbon mixture, comprising:
1-butene, a multiply unsaturated hydrocarbon and a mercaptan;
the process comprising:
feeding the C4 hydrocarbon mixture to a reactor comprising a heterogeneous catalyst;
feeding hydrogen to the reactor;
reacting the mercaptan with the multiply unsaturated hydrocarbon in the presence of the hydrogen in a liquid phase in the presence of the heterogeneous catalyst to obtain a thioether; and
separating the thioether from the C4 hydrocarbon mixture by distillation;
wherein
a molar ratio of the hydrogen to the multiply unsaturated hydrocarbon is from 1/100 to 8/10.
2. The process of claim 1 , wherein the molar ratio of the hydrogen to the multiply unsaturated hydrocarbons is in a range from 1/10 to 5/10.
3. The process of claim 1 , wherein the multiply unsaturated hydrocarbon is a compound selected from the group consisting of 1,3-butadiene, but-3-en-1-yne and 1,2-butadiene.
4. The process of claim 1 , wherein the mercaptan is at least one of ethanethiol and methanethiol.
5. The process of claim 1 , further comprising feeding carbon monoxide to the reactor, wherein a content of carbon monoxide fed to the reactor is less than 20 ppm, based on the mass of the C4 hydrocarbon mixture.
6. The process of claim 1 , wherein the heterogeneous catalyst comprises a metal of group VIII of the Periodic Table of the Elements.
7. The process of claim 1 , wherein the heterogeneous catalyst is a coated catalyst comprising aluminum oxide as a support and palladium as a catalytically active metal.
8. The process of claim 1 , wherein an entry temperature of feed into the reactor is in the range from 0° C. to 180° C.
9. The process of claim 1 , operated as a liquid-phase process in such a way that the hydrogen is completely dissolved in the liquid phase.
10. The process of claim 1 , further comprising distilling the C4 hydrocarbon mixture for removal of low boilers prior to removal of the mercaptans.
11. The process of claim 1 , further comprising, after the reacting, at least one operation selected from the group consisting of:
removal of the thioether by distillation;
removal of a sulfur component by adsorption;
selective hydrogenation of 1,3-butadiene to 1-butene and/or 2-butene;
removal of 1-butene by distillation;
oligomerization of 2-butenes to form olefins having more than 4 carbon atoms;
removal of n-butane and/or of isobutane by distillation; and
etherification of isobutene with methanol to form methyl tert-butyl ether (MTBE) and removal of the MTBE formed.
12. The process of claim 11 , comprising a combined removal of the thioether and 1-butene by distillation after the reacting.
13. The process of claim 11 , where an etherification of isobutene by methanol to form methyl tert-butyl ether (MTBE) follows the thioetherification, and an ether mixture comprising MTBE and the thioether is subsequently separated off by distillation.
14. The process of claim 1 , wherein an entry temperature of feed into the reactor is in the range from 60° C. to 150° C.
15. The process of claim 1 , wherein an entry temperature of feed into the reactor is in the range from 80° C. to 130° C.