Heavy crude oil hydroprocessing: A zeolite-based CoMo catalyst and its spent catalyst characterization

This study presents an effect of zeolite with alumina as a support for heavy oil hydroprocessing. The high surface area, moderately acidic meso- and macro-porous support was prepared with the mixing of alumina and ultra-stable Y zeolite (US-Y). The micro-structure and the composition of the zeolite crystals formed in the bulk of the alumina were examined by scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), and there were two main crystal phases homogeneously distributed in it. A CoMo sulfide supported catalyst is evaluated for hydroconversion of Maya heavy crude oil at moderate pressure conditions. The combination of ultra-stable zeolite and alumina is able to produce bi-modal type of pores in the catalyst which may contribute to a better combination of hydrodesulfurization (HDS), hydrodemetallization (HDM) and the selective cracking of asphaltene over the acidic catalysts. The characterization of spent catalysts can help as an assistance for the selection of optimum catalyst properties along with the reactor bed length and type of catalyst pore in each bed. The strapping reaction condition indicated that the acidic catalyst for heavy oil can be used more effectively at lower temperature. An increase in temperature showed that the HDM and hydrogenation of asphaltenes (HDAs) conversions are more affected than HDS and HDN. These results indicate occurrence of a thermal cracking of complex molecules like asphaltene and metal porphyrins, which is confirmed by the gaseous selectivity of the hydrocarbons.