Patent ID: 7344633

Claim:
A process to prepare a base oil having a saturates content of more than 90 wt %, a sulphur content of less than 0.03 wt %, and, a viscosity index of between 80 and 120 from a solvent refined base oil feedstock that is obtained by solvent extraction and solvent dewaxing of a distillate petroleum fraction having a boiling range between 300 and 620° C. and obtained by vacuum distillation of a residual fraction obtained by atmospheric distillation of a crude oil, wherein the solvent refined base oil feedstock comprises between 300 ppm and 2 wt % sulfur and between 70 and 90 wt % saturates, said process comprises: (a) contacting the solvent refined base oil feedstock in the presence of an upflowing hydrogen containing gas in a first reaction zone containing one or more fixed beds of a first catalyst, which the first catalyst comprises at least one Group VIB metal component and at least one non-noble Group VIII metal component supported on a refractory oxide carrier, wherein the flow of the solvent refined base oil feedstock within the first reaction zone is counter-current to the upflowing hydrogen containing gas and yielding from the first reaction zone a liquid fraction effluent and a gaseous stream; and (b) contacting the liquid fraction effluent of step (a), without first performing a separate gas/liquid separation of the liquid fraction effluent, in the presence of a hydrogen containing gas in a second reaction zone containing one or more fixed beds of a second catalyst, which the second catalyst comprises a noble metal component supported on an amorphous refractory oxide carrier and yielding from the second reaction zone the base oil.