Tailoring ZSM-5 zeolite porosity and acidity for efficient conversion of municipal solid waste to fuel

Abstract

Municipal solid waste contains essential building blocks of transportation fuel but is often deposited into landfills. Available conversion processes are still in their infancy; thus, requiring foundational knowledge to control reaction pathways and transform waste macromolecules into desired products. Active, robust, and low-cost catalysts with highly accessible active sites are needed for selective cleavage of certain bonds. The rapid deactivation and diffusion limitations are the major challenges to date which can be controlled by the catalyst pore structure and acidity. In this paper, we developed novel mesoporous ZSM-5 catalysts to maximise levoglucosan conversion, the dominant product of cellulose pyrolysis, into furfural. The concentration of levoglucosan dropped from 12.1% to 3.8% over the mesoporous ZSM-5. Furthermore, the pyrolysis of plastic materials that existed in the waste provided supplementary hydrogen, which synergistically contributed to the hydrodeoxygenation of some compounds like 5-hydroxymethylfurfural and 4-methyl-1,2-Benzenediol. The total amount of non-oxygenated compounds over the mesoporous catalyst reached 77% compared to 59.7% in non-catalytic pyrolysis based on 13 C NMR results. The integration of 13 C NMR and GC-MS results provided an effective tool in identifying key reaction pathways and linking that to the catalyst's textural and acidic properties. • Co-pyrolysis of biomass and polyethylene was catalysed by core-shell hierarchical ZSM-5. • The conversion of levoglucosan, the dominant product from cellulose, reached 68.3% over meso-ZSM-5. • Desired compounds including aliphatic C–C and hydrodeoxygenated products were obtained. • Accessible zeolite active sites were produced due to mesoporous networks enabling conversion of bulky sugar compounds.