Low-pressure process utilizing a stacked-bed system of specific catalysts for the hydrotreating of a gas oil feedstock
View Patent ↗A low-pressure process for hydrodenitrogenation and hydrodesulfurization of a gas oil feedstock. The process uses a multi-bed, stacked-bed reactor system. The first and third beds of the multi-bed, stacked-bed reactor system include catalysts that comprise cobalt and molybdenum supported on alumina. The middle, second bed, includes a catalyst comprising nickel and molybdenum supported on alumina that preferably includes an additive. The stacked bed arrangement with the use of the specific catalysts provides for the low-pressure operation and significantly improved HDN and HDS activity with relatively insignificant differences in hydrogen consumption.
1. A low-pressure process for the hydrodenitrogenation and hydrodesulfurization of a gas oil feedstock, wherein said low-pressure process comprises:
providing a stacked-bed reactor system that comprises a reactor vessel defining a reaction zone comprising: at least three catalyst beds positioned in a stacked spaced relationship to each other and providing a total bed volume with a first catalyst bed of a first bed volume that includes a first catalyst; a second catalyst bed of a second bed volume that includes a second catalyst; and a third catalyst bed of a third bed volume that includes a third catalyst, wherein:
said first catalyst comprises cobalt and molybdenum supported on alumina;
said second catalyst comprises a support material containing nickel, molybdenum, a hydrocarbon oil and a polar additive, which polar additive is an amide having a dipole moment greater than 0.45 debyes; and
said third catalyst comprises cobalt and molybdenum on an alumina support;
introducing a gas oil feedstock, having an organic nitrogen concentration and an organic sulfur concentration, into said reaction zone that is operated under a pressure in the range of 300 psig to 650 psig; and
yielding from said reaction zone a hydrotreated gas oil having reduced organic nitrogen concentration and organic sulfur concentration over those of said gas oil feedstock.
2. A low-pressure process as recited in claim 1 , wherein: said first bed volume is in the range of from 5 vol % to 25 vol % of said total bed volume within said reaction zone; said second bed volume is in the range of from 10 vol % to 50 vol % of said total bed volume within said reaction zone; and said third bed volume is in the range of from 25 vol % to 85 vol % of the total bed volume within said reaction zone.
3. A low-pressure process as recited in claim 2 , wherein: said first catalyst further comprises a heterocyclic additive.
4. A low-pressure process as recited in claim 3 , wherein: said third catalyst further comprises a heterocyclic additive.
5. A low-pressure process as recited in claim 4 , wherein said gas oil feedstock has a T10 of greater than 300° F. and a T90 of less than 750° F.
6. A low-pressure process as recited in claim 2 , wherein: said first catalyst further comprises a heterocyclic additive.
7. A low-pressure process as recited in claim 3 , wherein: said third catalyst further comprises a heterocyclic additive.
8. A low-pressure process as recited in claim 1 , wherein: said first bed volume is in the range of from 5 vol % to 25 vol % of said total bed volume within said reaction zone; said second bed volume is in the range of from 10 vol % to 50 vol % of said total bed volume within said reaction zone; and said third bed volume is in the range of from 25 vol % to 85 vol % of the total bed volume within said reaction zone.
9. A low-pressure process for the hydrodenitrogenation and hydrodesulfurization of a gas oil feedstock, wherein said low-pressure process comprises:
providing a stacked-bed reactor system that comprises a reactor vessel defining a reaction zone comprising: at least three catalyst beds positioned in a stacked spaced relationship to each other and providing a total bed volume with a first catalyst bed of a first bed volume that includes a first catalyst; a second catalyst bed of a second bed volume that includes a second catalyst; and a third catalyst bed of a third bed volume that includes a third catalyst, wherein:
said first catalyst comprises cobalt and molybdenum supported on alumina;
said second catalyst comprises a support material containing nickel, molybdenum,
and a heterocyclic additive; which heterocyclic additive has the formula C x H n N Y O z , wherein x is an integer of 3 or larger; y is either 0 or an integer in the range of from 1 to 3; z is either 0 or an integer in the range of from 1 to 3; and n is the number of hydrogen atoms required to fill the remaining bonds with the carbon atoms of the molecule; and
said third catalyst comprises cobalt and molybdenum on an alumina support;
introducing a gas oil feedstock, having an organic nitrogen concentration and an organic sulfur concentration, into said reaction zone that is operated under low-pressure condition; and
yielding from said reaction zone a hydrotreated gas oil having significantly reduced organic nitrogen concentration and organic sulfur concentration over those of said gas oil feedstock.