Catalytic cracking of low-density polyethylene over zeolite-containing hierarchical two-layered catalyst with different mesopore size using Curie point pyrolyzer

Abstract

Zeolite-containing hierarchical two-layered (ZC2L) catalysts were prepared by the gel skeletal reinforcement method. Their reactivity was estimated in catalytic cracking of low-density polyethylene (LDPE) at 590°C using a Curie point pyrolyzer method. In addition, the “relative activity” per amount of zeolite in the catalyst was calculated, and the relationship between the pore and acid properties of each catalyst was investigated. The results suggested that the presence of both mesopores and the strong acid sites of zeolite would be closely related to the increase in activity. ZSM-5-ZC2L catalysts showed much higher aromatics selectivity especially for toluene and p-xylene than ZSM-5 single and kaolin-mixed catalysts. In contrast to the cases of ZSM-5-containing catalysts, β-zeolite-containing catalysts and Y-zeolite-containing catalysts selectively produced i-olefins and i-paraffins, respectively. The product selectivity of the ZC2L catalyst was influenced by the size of the micropores of the zeolite while the hierarchical ZC2L catalysts with a small amount (26 wt%) of zeolite exhibited the higher activity than zeolite single catalysts.