| 主权项 |
1. A process for the treatment of a gasoline comprising diolefins, olefins and sulphur-containing compounds including mercaptans, said process comprising the following steps:
a) carrying out a step for demercaptanization by addition of at least a portion of the mercaptans onto the olefins by bringing gasoline into contact with at least one first catalyst, at a temperature in the range 50° C. to 250° C., at a pressure in the range 0.4 to 5 MPa and with a liquid hourly space velocity (LHSV) in the range 0.5 to 10 h−1, the first catalyst being in the sulphide form and comprising a first support, at least one metal selected from group VIII and at least one metal selected from group VIb of the periodic classification of the elements, the first catalyst having the following characteristics:
a support constituted by a gamma alumina with a specific surface area in the range 180 m2/g to 270 m2/g;the quantity of metal from group VIb, expressed in the oxide form, is in the range 4% to 20% by weight with respect to the total catalyst weight;the quantity of metal from group VIII, expressed in the oxide form, is in the range 3% to 15% by weight with respect to the total catalyst weight;the molar ratio between the metal from group VIII and the metal from group VIB is in the range 0.6 to 3 mol/mol; b) in a distillation column, carrying out fractionation of the gasoline obtained from step a) into at least one first intermediate light gasoline cut with a total sulphur content below that of the starting gasoline and a second intermediate heavy gasoline cut containing the major proportion of the starting sulphur-containing compounds; c) introducing a stream of hydrogen and at least the second intermediate heavy gasoline cut obtained from step b) into a catalytic distillation column (14) comprising at least one reaction zone (15) including at least one second catalyst in the sulphide form comprising a second support, at least one metal from group VIII and a metal from group VIb, with the quantity of metal from group VIII, expressed as the oxide, in the range 0.5% to 25% by weight with respect to the weight of catalyst and with the quantity of metal from group VIb, expressed as the oxide, in the range 1.5% to 60% by weight with respect to the weight of catalyst, the conditions in the catalytic distillation column being selected so as to bring the intermediate heavy gasoline obtained from step b) into contact, in the presence of hydrogen, with the second catalyst in order to decompose the sulphur-containing compounds into H2S, contact with the second catalyst being carried out at a pressure in the range 0.1 to 4 MPa and at a temperature in the range 210° C. to 350° C.; d) evacuating at least one final light gasoline fraction comprising H2S and a desulphurized heavy gasoline fraction from the catalytic distillation column, the final light gasoline fraction being evacuated at a point located above the reaction zone and the desulphurized heavy gasoline fraction being evacuated at a point located below the reaction zone. |
