METHOD FOR PREPARING MERCAPTANS BY SULFHYDROLYSIS OF DIALKYL SULFIDES WITH CATALYST PRETREATMENT

1 . A process for preparing at least one mercaptan, comprising the following steps:

i) treatment of a catalyst for the sulfhydrolysis of at least one dialkyl sulfide, comprising the following steps:

1) heating said catalyst, preferably in the presence of an inert gas; and

2) placing said catalyst in contact with hydrogen sulfide (H 2 S); and then

ii) a sulfhydrolysis reaction in which at least one dialkyl sulfide is reacted with H 2 S in the presence of said catalyst treated according to step i), to obtain at least one mercaptan;

said catalyst being a zeolite.

2 . The process according to claim 1 , in which said catalyst is a Y-type zeolite.

3 . The process according to claim 1 , in which said catalyst comprises between 0% and 10% by weight of promoter, preferably between 0% and 2% by weight of promoter, for example between 0.01% and 2% by weight of promoter, relative to the total weight of said catalyst.

4 . The preparation process according to claim 1 , in which the treatment of the catalyst according to step i) is performed in the reactor in which the sulfhydrolysis of the dialkyl sulfide according to step ii) is then performed.

5 . The preparation process according to claim 1 , in which the heating step 1) is performed in the presence of an inert gas and at a temperature of between 70° C. and 350° C., more particularly between 80° C. and 250° C., and preferably between 80° C. and 150° C. and at a pressure of between 0.1 and 50 bar absolute, in particular between 0.1 and 10 bar absolute, preferably between 0.8 and 2 bar absolute.

6 . The preparation process according to claim 1 , in which step 2) of placing in contact with H 2 S is performed at a temperature of between 20° C. and 450° C., for example between 250° C. and 400° C., preferably between 320° C. and 370° C., and at a pressure of between 0.1 and 50 bar absolute, more particularly between 1 and 20 bar absolute, for example between 1 and 15 bar absolute.

7 . The preparation process according to claim 1 , in which, in the sulfhydrolysis reaction, the H 2 S/dialkyl sulfide mole ratio is between 0.1/1 and 50/1, preferably between 2/1 and 20/1, more preferentially between 2/1 and 8/1.

8 . The preparation process according to claim 1 , in which the dialkyl sulfide is chosen from the group consisting of: dimethyl sulfide, diethyl sulfide, dioctyl sulfide, didodecyl sulfide and methyl ethyl sulfide, preferably dimethyl sulfide.

9 . A process for preparing at least one mercaptan, preferably continuously, comprising the following steps:

A) H 2 S and at least one alcohol are introduced into a first reactor;

B) the H 2 S and said at least one alcohol are reacted to obtain an outlet stream comprising at least one mercaptan and at least one dialkyl sulfide and possibly H 2 S;

C) the stream comprising at least one mercaptan, at least one dialkyl sulfide and possibly H 2 S is separated into:

a stream F1 comprising the mercaptan(s),

a stream F2 comprising the dialkyl sulfide(s), and

optionally a stream F3 comprising H 2 S;

D) optionally, stream F2 is purified to obtain a stream F2′ enriched in dialkyl sulfide(s);

E) stream F2 or F2′ is introduced with H 2 S into a second reactor, said reactor comprising a catalyst treated according to the treatment of step i) as claimed in claim 1 ;

F) a sulfhydrolysis reaction of the dialkyl sulfide(s) with H 2 S is performed to obtain an outlet stream F4 comprising said mercaptan(s) and possibly H 2 S;

G) optionally, stream F4 obtained from step F) is recycled into step A).