Method for hydrodesulfurization in the presence of a catalyst on a mesoporous-macroporous substrate
For hydrodesulfurization of an olefinic gasoline cut containing sulfur, the gasoline cut, hydrogen, and a catalyst are brought into contact. The catalyst comprises a group VIB metal, a group VIII metal, and a mesoporous and macroporous alumina substrate having a bimodal mesopore distribution. The volume of mesopores having a diameter greater than or equal to 2 nm and less than 18 nm corresponds to between 10 and 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 corresponds to between 30 and 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 corresponds to between 30 and 50% by volume of the total pore volume of the substrate.
1 . A process for hydrodesulfurization of an olefinic gasoline cut containing sulfur, wherein said olefinic gasoline cut, hydrogen and a catalyst are brought into contact, said hydrodesulfurization process being carried out at a temperature of between 200° C. and 400° C., a total pressure of between 1 and 3 MPa, an hourly space velocity, defined as being the volume flow rate of feedstock relative to the volume of catalyst, of between 1 and 10 h −1 and a hydrogen/olefinic gasoline cut volume ratio of between 100 and 600 N1/1, 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 corresponds to between 10% and 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 corresponds to between 30% and 50% by volume of the total pore volume of said mesoporous and macroporous alumina support;
the volume of macropores with a diameter greater than or equal to 50 nm and less than 8000 nm corresponds to between 30% and 50% by volume of the total pore volume of said mesoporous and macroporous alumina support.
2 . The process as claimed in claim 1 , wherein said mesoporous and macroporous alumina support comprises a specific surface area of between 50 and 210 m 2 /g.
3 . The process as claimed in claim 1 , wherein said mesoporous and macroporous alumina support comprises a total pore volume of between 0.7 and 1.3 ml/g.
4 . The process as claimed in claim 1 , wherein the volume of mesopores with a diameter greater than or equal to 2 nm and less than 18 nm corresponds to between 15% and 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 mesopores with a diameter greater than or equal to 18 nm and less than 50 nm corresponds to between 35% and 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 macropores with a diameter greater than or equal to 50 nm and less than 8000 nm corresponds to between 35% and 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 between 1% and 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 between 0.5% and 10% by weight relative to the total weight of the catalyst.
9 . The process as claimed in claim 1 , wherein the at least one the group VIII metal is cobalt.
10 . The process as claimed in claim 1 , wherein the at least one the group VIB metal is molybdenum.
11 . The process as claimed in claim 1 , wherein said catalyst further comprises phosphorus, the content of phosphorus, expressed in P 2 O 5 form, is between 0.1% and 10% by weight relative to the total weight of said catalyst.
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 between 10.5 and 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 between 22 and 28 nm.
14 . The process as claimed in claim 1 , wherein the olefinic gasoline cut 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 between 2 and 4 mm.
16 . The process as claimed in claim 15 , wherein said mesoporous and macroporous alumina support is obtained according to the following steps:
s1) dehydrating an aluminum hydroxide or an aluminum oxyhydroxide at a temperature of between 400° C. and 1200° C. for a time of between 0.1 second and 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 on conclusion of step s3) by impregnation with water or an aqueous solution, then residence in an autoclave at a temperature of between 100° C. and 300° C.;
s5) calcining the alumina beads obtained on conclusion of step s4) at a temperature of between 500° C. and 820° C.
17 . The process as claimed in claim 15 , wherein the dehydrating of aluminum hydroxide or aluminum oxyhydroxide is performed at a temperature of between 600° C. and 900° C., for a time of between 0.1 second and 4 seconds, to obtain the alumina powder.