Amorphous TiO_2 and SiO_2 Modified Alumina as Catalyst Support for Hydroprocessing of Maya Crude Oil Heavy Fractions

摘要

A series of aluminas modified with 3-15 wt% SiO_2 (AMASAs) and 2-9 wt% TiO_2 (AMATAs) were prepared by a deposition and/or coprecipitation methods. The pore size distribution was varied by means of a pH-swing procedure where alternating pH acid-alkaline values generated 100-200 A pores, particularly in the AMASAs case. However, the incorporation of TiO_2 in the AMATAs even after the pH-swing procedure results in a pore size and volume decrease The degree of TiO_2 reduction is much higher in AMATAs obtained by deposition than those obtained by coprecipitation. The use of AMASAs as catalyst supports of 2.4 wt% Ni and 8.8 wt% Mo in the hydroconversion of a vacuum distillation residue brings about 1.5 times higher conversion to lighter fractions in comparison with a commercial alumina-based catalyst. AMATA-based catalyst shows similar activity and selectivity to the commercial catalyst. However, the presence of TiO_2 (6 wt%) considerably increases the N and V removal, and decreases the formation of sediments.