Method for the selective hydrogenation of a gasoline in the presence of a catalyst on a mesoporous-macroporous substrate
A method for selective hydrogenation of gasoline including polyunsaturated compounds and light sulfur compounds wherein the gasoline and hydrogen is brought into contact with a catalyst containing a group VIB metal, a group VIII metal and a mesoporous and macroporous alumina substrate having a bimodal mesopore distribution and wherein the volume of mesopores having a diameter greater than or equal to 2 nm and less than 18 nm is 10 to 30% by volume of the total pore volume of the substrate, the volume of mesopores having a diameter greater than or equal to 18 nm and less than 50 nm is 30 to 50% by volume of the total pore volume of the substrate; the volume of macropores having a diameter greater than or equal to 50 nm and less than 8000 nm is 30 to 50% by volume of the total pore volume of the substrate.
1 . A process for selective hydrogenation of a gasoline comprising polyunsaturated compounds and light sulfur compounds having a boiling point lower than 84° C., said process comprising bringing into contact the gasoline and hydrogen with a catalyst, at a temperature of 80° C. to 220° C., with a liquid space velocity of 1 h −1 to 10 h −1 and a pressure of 0.5 to 5 MPa, and with a molar ratio between the hydrogen and diolefins to be hydrogenated in the gasoline of greater than 1 and less than 100 mol/mol, said catalyst comprising at least one group VIB metal, at least one group VIII metal, and a mesoporous and macroporous alumina support comprising a bimodal distribution of mesopores and wherein:
the volume of mesopores with a diameter greater than or equal to 2 nm and less than 18 nm is 10% to 30% by volume of the total pore volume of said mesoporous and macroporous alumina support;
the volume of mesopores with a diameter greater than or equal to 18 nm and less than 50 nm is 30% to 50% by volume of the total pore volume of said mesoporous and macroporous support; and
the volume of macropores with a diameter greater than or equal to 50 nm and less than 8000 nm is 30% to 50% by volume of the total pore volume of said mesoporous and macroporous support.
2 . The process as claimed in claim 1 , wherein said mesoporous and macroporous alumina support has a specific surface area of 50 to 210 m 2 /g.
3 . The process as claimed in claim 1 , wherein said mesoporous and macroporous alumina support has a total pore volume of 0.7 to 1.3 ml/g.
4 . The process as claimed in claim 1 , wherein the volume of the mesopores with a diameter greater than or equal to 2 nm and less than 18 nm is 15% to 25% by volume of the total pore volume of said mesoporous and macroporous alumina support.
5 . The process as claimed in claim 1 , wherein the volume of the mesopores with a diameter greater than or equal to 18 nm and less than 50 nm is 35% to 45% by volume of the total pore volume of said mesoporous and macroporous alumina support.
6 . The process as claimed in claim 1 , wherein the volume of the macropores with a diameter greater than or equal to 50 nm and less than 8000 nm is 35% to 50% by volume of the total pore volume of said mesoporous and macroporous alumina support.
7 . The process as claimed in claim 1 , wherein the content of the at least one group VIB metal in said catalyst, expressed in oxide form, is 1% to 30% by weight relative to the total weight of the catalyst.
8 . The process as claimed in claim 1 , wherein the content of the at least one group VIII metal in said catalyst, expressed in oxide form, is 1% to 20% by weight relative to the total weight of the catalyst.
9 . The process as claimed in claim 1 , wherein the molar ratio of the at least one group VIII metal to the at least one group VIB metal is 0.3 to 3 mol/mol.
10 . The process as claimed in claim 1 , wherein the at least one group VIII metal is nickel.
11 . The process as claimed in claim 1 , wherein the at least one group VIB metal is molybdenum.
12 . The process as claimed in claim 1 , wherein the pore distribution of the mesopores with a diameter greater than or equal to 2 nm and less than 18 nm is centered on a range of values of 10.5 to 14.5 nm.
13 . The process as claimed in claim 1 , wherein the pore distribution of the mesopores with a diameter greater than or equal to 18 nm and less than 50 nm is centered on a range of values of 22 to 28 nm.
14 . The process as claimed in claim 1 , wherein the gasoline is a catalytic cracking gasoline.
15 . The process as claimed in claim 1 , wherein the mesoporous and macroporous alumina support is in the form of beads with a diameter of 2 to 4 mm.
16 . The process as claimed in claim 15 , wherein said mesoporous and macroporous alumina support has been obtained according to the following steps:
s1) dehydrating an aluminum hydroxide or an aluminum oxyhydroxide at a temperature of 400° C. to 1200° C. for a time of 0.1 second to 5 seconds to obtain an alumina powder;
s2) shaping said alumina powder obtained in step s1) in the form of beads;
s3) heat treating the alumina beads obtained in step s2) at a temperature above or equal to 200° C.;
s4) hydrothermally treating the alumina beads obtained at the end of step s3) by impregnation with water or an aqueous solution, then residence in an autoclave at a temperature of 100° C. to 300° C.;
s5) calcining the alumina beads obtained at the end of step s4) at a temperature of 500° C. to 820° C.
17 . The process as claimed in claim 16 , wherein, in step s1), the dehydrating the aluminum hydroxide or the aluminum oxyhydroxide occurs at a temperature of 600° C. to 900° C. for a time of 0.1 second to 4 seconds.
18 . The process as claimed in claim 1 , wherein said catalyst does not comprise phosphorus.
19 . The process as claimed in claim 1 , wherein the gasoline after being brought into contact with the catalyst has a surfur content of less than 10 ppm.
20 . The process as claimed in claim 1 , wherein the gasoline after being brought into contact with the catalyst contains less than 0.5% by weight of diolefins.