Method for conducting finishing hydrodesulphurisation in the presence of a catalyst on a meso-macroporous support
Method for treating a partially desulphurised sulphur-containing hydrocarbon feedstock from a preliminary hydrodesulphurisation step in the presence of a catalyst comprising an active phase comprising a group VII metal and a mesoporous and macroporous alumina support comprising a bimodal distribution of mesopores, wherein: —the volume of mesopores having a diameter greater than or equal to 2 nm and less than 18 nm is between 10 and 30% by volume of the total pore volume of the support; —the volume of mesopores having a diameter greater than or equal to 18 nm and less than 50 nm is between 30 and 50% by volume of the total pore volume of the support; —the volume of macropores having a diameter greater than or equal to 50 nm and less than 8000 nm is between 30 and 50% by volume of the total pore volume of the support.
1. A process for treating a partially desulfurized, sulfur-containing hydrocarbon feedstock resulting from a preliminary step of catalytic hydrodesulfurization, said process comprising:
subjecting said feedstock to partially desulfurization at a temperature of between 200° C. and 400° C., a pressure of between 0.2 and 5 MPa, at an hourly space velocity, defined as the volume flow rate of feedstock at the inlet per volume of catalyst used, of between 0.1 h −1 and 20 h −1 , in the presence of a catalyst comprising an active phase comprising at least one group VIII metal, said active phase not comprising any group VIB 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 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 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 support.
2. The process as claimed in claim 1 , wherein said support comprises a specific surface area of between 50 and 210 m 2 /g.
3. The process as claimed in claim 1 , wherein said 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 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 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 support.
7. The process as claimed in claim 1 , wherein the content of group VIII metal in said catalyst, expressed as group VIII element, is between 5% and 65% by weight relative to the total weight of said catalyst.
8. The process as claimed in claim 1 , wherein the group VIII metal is nickel.
9. 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.
10. 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.
11. The process as claimed in claim 1 , wherein said support comprises a specific surface area of between 70 and 180 m 2 /g.
12. The process as claimed in claim 1 , wherein said support is in the form of beads with a diameter of between 2 and 4 mm.
13. The process as claimed in claim 12 , wherein said 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 at the end 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 at the end of step s4) at a temperature of between 500° C. and 820° C.
14. The process as claimed in claim 1 , wherein said partially desulfurized hydrocarbon feedstock contains less than 100 ppm by weight of sulfur.
15. The process as claimed in claim 13 , wherein dehydrating in s1) is carried out at a temperature of between 600° C. and 900° C.
16. The process as claimed in claim 13 , wherein dehydrating in s1) is carried out for a time of between 0.1 second and 4 seconds.
17. The process as claimed in claim 15 , wherein dehydrating in s1) is carried out for a time of between 0.1 second and 4 seconds.