Hydroprocessing of solvent-refined coal: catalyst-screening results

This report presents the results of screening four catalysts for hydroprocessing a 50 wt% mixture of SRC-I in a prehydrogenated creosote oil using a continuous flow unit. All catalysts employed were nickel-molybdates with varying properties. Reaction conditions were 2000 psi, 8 SCFH of hydrogen, volume hourly space velocity of 0.6 to 1.0 cc of SRC-I/hr/cc of catalyst, and 48 hours at 750/sup 0/F followed by 72 hours at 780/sup 0/F. The results indicate that the Shell 324 catalyst is best for hydrogenation of the feedstock but only marginally better than CB 81-44 for denitrogenation. The CB 81-44 catalyst may be slightly better than Shell 324 for the conversion of the +850/sup 0/F fraction of the feedstock. Desulfurization was uniformly high for all catalysts. Catalysts with a bimodal pore size distribution (i.e., SMR7-6137(1)) appear to be better for denitrogenation than unimodal catalysts (i.e., SMR7-6137(4)) containing the same metals loading. Unimodal catalysts (i.e., Shell 324) with higher metals loadings are comparable to bimodal catalysts (i.e., CB 81-44) containing less metals. The results indicate that pore size distribution and metals loading are important parameters for high activity. Catalysts with a unimodal pore volume distribution are capable of being restored to their original state, while bimodal ones experience a loss in surface area and pore volume and an increase in pellet density. This is attributed to the more efficient use of the interior surface area of the catalyst, which results in higher accumulation of coke and metals. Since coke can be removed via controlled oxidation, the irreversible loss is due to the higher concentrations of metals in the catalyst