NI-MO/AL2O3 CATALYSTS PROMOTED WITH PHOSPHORUS AND FLUORIDE

Ni-Mo/Al2O3 catalysts containing two promoters, fluoride and phosphorus, were studied to learn whether the benefits of both promoters could be combined to produce a superior catalyst. Initially, two series of catalysts differing in the sequence of impregnation of the additives were prepared and tested in the hydrocracking of cumene and the hydrodesulfurization of thiophene. Catalysts impregnated in the sequence phosphorus-metals (Ni and Mo)-fluoride were clearly superior to those prepared by adding first phosphorus, then fluoride and finally metals. The more effective series of catalysts was tested in the hydroprocessing of a gas oil feedstock; to determine the resistance of these surfaces to poisoning, tests were also carried out with the same feedstock spiked with quinoline. The bi-promoted catalysts retained fluoride well, and were quite effective in hydrogenation and hydrodesulfurization. They were even more effective than phoshorous-only promoted catalysts in quinoline hydrodenitrogenation.