Process for producing a gasoline with a low sulphur and mercaptans content

A process for the treatment of a gasoline containing sulphur-containing compounds and olefins, the process comprising at least the following steps:

• a) bringing the gasoline, hydrogen and a hydrodesulphurization catalyst into contact in at least one reactor at a temperature in the range of 200° C. to 400° C., at a pressure in the range of 0.5 to 5 MPa, at an hourly space velocity in the range of 0.5 to 20 h−1 and with a ratio between the flow rate of hydrogen, expressed in normal m3 per hour, and the flow rate of the feed to be treated, expressed in m3 per hour under standard conditions, in the range of 50 Nm3/m3 to 1000 Nm3/m3, in order to convert at least a portion of the sulphur-containing compounds into H2S and to produce an effluent;
• b) carrying out a step for separating the H2S which is formed and present in the effluent obtained from step a) and in which the effluent obtained is mixed with an olefinic C4 cut;
• c) bringing the H2S-depleted effluent obtained from step b) into contact, in a reactor, with a catalyst containing at least one sulphide of at least one transition metal or lead deposited on a porous support, step c) being carried out at a temperature in the range of 30° C. to 250° C., with a liquid hourly space velocity in the range of 0.5 to 10 h−1, a pressure in the range of 0.2 to 5 MPa and with a H2/feed ratio in the range of 0 to 25 Nm3 of hydrogen per m3 of feed, in order to produce a gasoline obtained from step c) with a reduced mercaptans content compared with that of the effluent obtained from step b), and the effluent obtained is fractionated so as to separate an unreacted olefinic C4 cut and said unreacted olefinic C4 cut is recycled to the reactor for step c).

A process for the treatment of a gasoline containing sulphur-containing compounds and olefins, the process comprising at least the following steps:

• a) bringing the gasoline, hydrogen and a hydrodesulphurization catalyst into contact in at least one reactor at a temperature in the range of 200° C. to 400° C., at a pressure in the range of 0.5 to 5 MPa, at an hourly space velocity in the range of 0.5 to 20 h−1 and with a ratio between the flow rate of hydrogen, expressed in normal m3 per hour, and the flow rate of the feed to be treated, expressed in m3 per hour under standard conditions, in the range of 50 Nm3/m3 to 1000 Nm3/m3, in order to convert at least a portion of the sulphur-containing compounds into H2S and to produce an effluent;
• b) carrying out a step for separating the H2S which is formed and present in the effluent obtained from step a);
• wherein the resultant effluent is mixed with a hydrocarbon cut, which is an olefinic C4 cut, providing an H2S-depleted effluent mixture,
• c) bringing the H2S-depleted effluent mixture into contact, in a reactor, with a catalyst containing at least one sulphide of at least one transition metal or lead deposited on a porous support, step c) being carried out at a temperature in the range of 30° C. to 250° C., with a liquid hourly space velocity in the range of 0.5 to 10 h−1, a pressure in the range of 0.2 to 5 MPa and with a H2/feed ratio in the range of 0 to 10 Nm3 of hydrogen per m3 of feed, wherein mercaptans and olefins are reacted and produce thioether compounds and produce a gasoline obtained from step c) with a reduced mercaptans content compared with that of the effluent obtained from step b), and
• wherein the effluent obtained from step c) is fractionated so as to separate an unreacted olefinic C4 cut and said unreacted olefinic C4 cut is recycled to the reactor for step c).