Catalytic Cracking of an Australian Coal-Derived Liquid Heavy Feedstock on HY and HZSM-5 Zeolites

Abstract

The catalytic reactions of a severely hydrotreated CDL heavy feed were investigated on HY and HZSM-5 zeolites at 480 C over a range of catalyst-to-feed ratios. The formation of gaseous (<C5) and gasoline range (C5-ClO) products was closely followed. A higher gasoline yield was observed from cracking on HY zeolite, reaching a maximum of -40 wt % at 70% feed conversion (compared with -15 wt % over HZSM-5 at 40% conversion). Greater gas yields were observed from reaction on the pentasil. Although a reduced gasoline yield was obtained from reaction on HZSM-5, it had a higher octane rating compared with that obtained from reaction on the faujasite, possibly due to the higher concentration of alkenes and aromatics produced on the pentasil. The concentration of selected aromatics falling outside the gasoline range was found to increase with conversion, while the reactivity of linear alkanes (originally present in the starting feedstock) increased with chain length. Observed differences in product yield and selectivity from reaction on HY and HZSM-5 were attributed to the different pore diameters, acidity, and hydrogen-transfer potential of the two zeolites.