Formation of Middle Olefines by Catalytic Cracking of Petroleum Hydrocarbons and Deactivation of Catalyst

Abstract

Deactivation of silica-alumina catalyst and secondary reactions during the cracking of petroleum hydrocarbons were investigated, using fixed and fluidized bed reactors. Emphasis was placed on coke formation, hydrogenation and effect of molecular hydrogen on cracking reaction. The activity decreased more rapidly at lower temperatures, and feed rate did not affect the deactivation rate of catalyst. Main products at earlier stage of reaction were branched paraffins, and olefines were predominant at later. From this fact it was understood that the rate of hydrogenation reaction decreased more rapidly than that of cracking. The hydrogenation of olefines was proportional to the coke formation. In the presence of molecular hydrogen, the deterioration of catalyst activity was small and the olefine content of products was large. From these facts a mechanism of hydrogenation reaction was investigated.