Deep desulphurization of low sulphur content feedstock
The invention pertains to a process for deep desulphurization of low sulphur content feedstock comprising the steps of providing a low sulphur content hydrocarbon feedstock and contacting said hydrocarbon feedstock with a cobalt-molybdenum desulphurizing system or a nickel-molybdenum desulphurizing system in an oxide form in order to obtain a very low sulphur product comprising less than 5 ppm by weight sulphur.
1. Process for deep desulphurization of low sulphur content hydrocarbon feedstock comprising the steps of:
a) providing a low sulphur content hydrocarbon feedstock comprising less than 50 ppm by weight sulphur,
b) providing a desulphurizing system comprising a Group VI element selected from cobalt and nickel and a Group VIII element being molybdenum, the Group VI and Group VIII elements being in oxide form,
c) optionally drying the desulphurizing system by submitting it to a hydrogen flow at a temperature lower than 250° C.,
d) desulphurizing the low sulphur content hydrocarbon feedstock by contacting said hydrocarbon feedstock with the optionally dried desulphurizing system in the presence of hydrogen, at a temperature ranging from 220 to 420° C. and at a pressure of less than or equal to 80 bar, to obtain a hydrocarbon fluid comprising less than 5 ppm by weight sulphur, wherein the process further comprises a step of:
e) hydrodearomatizing the obtained hydrocarbon fluid comprising less than 5 ppm by weight sulphur.
2. The process of claim 1 , wherein the Group VI/Group VIII desulphurizing system is a cobalt-molybdenum desulphurizing system in oxide form.
3. The process of claim 2 , wherein the cobalt-molybdenum desulphurizing system in oxide form comprises cobalt oxide and molybdenum trioxide.
4. The process of claim 1 , wherein the Group VI/Group VIII desulphurizing system is supported on alumina or silica-alumina.
5. The process of claim 1 , wherein the hydrogen flow ranges from 60 to 100 NL/h for 30 minutes to 2 hours.
6. The process of claim 1 , wherein the pressure is less than or equal to 70 bar.
7. The process of claim 1 , wherein the temperature ranges from 240 to 400° C.
8. The process of claim 1 , wherein said hydrocarbon feedstock is contacted with the optionally dried desulphurizing system with a hydrogen to hydrocarbon ratio H 2 /HC ranging from 250 to 350 NL/L.
9. The process of claim 1 , wherein the Liquid Hourly Space Velocity ranges from 0.1 to 5 h −1 .
10. The process of claim 1 , wherein the low sulphur content hydrocarbon feedstock comprises less than 30 ppm by weight sulphur.
11. The process of claim 1 , wherein the low sulphur content hydrocarbon feedstock contains less than 5 ppm by weight of dissolved hydrogen sulphide, based on the total weight of the low sulphur content hydrocarbon feedstock.
12. The process of claim 1 , wherein the low sulphur content hydrocarbon feedstock has an initial boiling point and a final boiling point between 100° C. and 400° C.
13. The process of claim 1 , wherein the low sulphur content hydrocarbon feedstock has a distillation range defined by the difference between the final boiling point and the initial boiling point, not exceeding 80° C.
14. The process of claim 1 , wherein the obtained hydrocarbon fluid comprises less than 3 ppm by weight sulphur.
15. The process of claim 5 , wherein the hydrogen flow ranges from 60 to 100 NL/h at a temperature ranging from 100° C. to 200° C.
16. The process of claim 1 , wherein the Liquid Hourly Space Velocity ranges from 0.3 h −1 to 2 h −1 .
17. The process of claim 1 , wherein the Group VI/Group VIII desulphurizing system is a cobalt-molybdenum desulphurizing system in oxide form supported on alumina or silica-alumina.
18. The process of claim 1 , wherein said hydrocarbon feedstock is contacted with the optionally dried desulphurizing system with a hydrogen to hydrocarbon ratio H 2 /HC ranging from 250 to 350 NL/L and with a Liquid Hourly Space Velocity ranging from 0.3 h −1 to 2 h −1 .
19. The process of claim 1 , wherein the contacting temperature ranges from 250 to 380° C.