Catalytic cracking reaction of vacuum gas oil and atmospheric residue by zeolite-containing microporous and mesoporous composites using Curie point pyrolyzer

Abstract

Silica-aluminas with very large mesopores were prepared by the gel skeletal reinforcement technique and were combined with microporous zeolite, resulting in the formation of catalysts with hierarchical structure. Catalytic cracking of vacuum gas oil (VGO) and atmospheric residue (AR), specifically the influence of the pore size of the catalysts on the reactivity of VGO and AR, was investigated using a Curie point pyrolyzer, as a new evaluation technique. Comparing the catalytic cracking of VGO with that of AR, the selectivity for gas products in AR cracking was higher than that in VGO cracking, indicating that dealkylation of aromatic components proceeded. With respect to cracking of VGO the conversion was improved due to the increase in diffusion rate of raw materials with increasing pore size for both β and Y zeolite-containing catalysts. In contrast to the reaction of VGO, the remarkable dependence was hardly observed between conversion and pore size in the cracking of AR presumably because AR, which contained large amounts of heavy fractions with higher boiling point than 500°C, was difficult to diffuse even in the inside of large pores.Regarding on the type of zeolite included, more than 70% gasoline selectivity from both VGO and AR was obtained by Y zeolite-containing catalysts. In contrast to this, the gasoline selectivity of about 60% from VGO cracking and 50% from AR cracking, was observed for β zeolite containing catalysts. These results suggested that so-called “supercage”, which is included in the inside of the micropores of Y zeolite, would be rather larger than a similar cage of β zeolite which induced higher gasoline selectivity for Y zeolite-containing catalysts.