A COMPARATIVE GAS OIL HYDROPROCESSING STUDY OF ALUMINA, CARBON, AND CARBON-COVERED ALUMINA SUPPORTED NI-MO CATALYSTS - EFFECT OF QUINOLINE, THIOPHENE, AND VANADIUM SPIKING

Catalysts with 3-15 wt % NiO-MoO3 supported on alumina, carbon-covered alumina, and carbon were used to hydroprocess gas oil spiked with quinoline, thiophene, and vanadium to give an insight into the relationship between the support and deactivation. Experiments were carried out in a batch reactor at 410-degrees-C and 1000 psi initial H-2 pressure. It was found that N, S, and V compounds in the feed suppress the hydrogen uptake by gas oil hydroprocessed with alumina or carbon-covered alumina supported catalysts but carbon supported catalysts are insensitive to these compounds. Quinoline HDN and thiophene HDS do occur thermally to a small extent but a catalyst is required for efficient HDN and HDS. Under the conditions used for our experiments, quinoline is rapidly hydrogenated to 1,2,3,4-tetrahydroquinoline and it is the subsequent C-N bond hydrogenolysis that is the rate-determining step. For hydroprocessing the high nitrogen content quinoline spiked gas oil, the carbon supported catalyst is comparable to the alumina supported catalyst for sulfur removal but is superior for quinoline HDN. Basic nitrogen compounds, such as quinoline, have an affinity for acidic catalyst surfaces and undergo coking reactions thereby deactivating metal centers and reducing the total surface area. The use of a carbonaceous support decreases the amount of coke deposited on the catalyst surface.