Aviation fuel hydrocarbons from camphorwood and low-density polyethylene: Cascade catalytic approach with CaO and Zn/HBeta

Abstract

In this study, the co-pyrolysis of camphorwood and low-density polyethylene employing a cascade catalyst system consisting of CaO and Zn-modified HBeta in a fixed-bed reactor was investigated for the production of aviation fuel hydrocarbons (C8–C16). The effect of Zn loading on HBeta, CaO to Zn/HBeta mass ratio, and the feedstock to catalyst mass ratio on both oil yield and composition was investigated. Results revealed that loading Zn onto HBeta led to ZnO cluster and oxygen-bridged Zn dimers ([ZnOZn]2+) formation, which affects HBeta's acid properties and aromatization capacity. The 10 wt%Zn/HBeta catalyst with more ZnO content exhibited weak acid sites, and moderate aromatization capacity, increasing oil yield from 32.06 to 44.25 wt% compared to 3 wt%Zn/HBeta and favoring presence of straight-chain components in oil products. CaO also enhanced straight-chain alkane formation. The highest oil yield, reaching 48.44 wt%, was obtained when CaO and 10 wt%Zn/HBeta cascade by a 1:1 mass ratio was adopted, producing oil with aviation fuel with a maximum yield of 18.45 wt%, and selectivity of 38.09 area%, of which 26.54 area% being aromatics and 11.55 area% being alkanes. Furthermore, the feedstock-to-catalyst ratio influenced the products significantly, with lower feedstock-to-catalyst ratio enhanced aromatization and the ratio of 2:1 recommended. Therefore, this cascade catalytic approach, which combines cost-effective CaO and 10 wt%Zn/HBeta catalysts shows significant potential for enhancing bio-aviation fuel production from solid wastes. Moreover, it provides a viable and promising solution for addressing concerns related to low oil yield and excessive aromatization.