Assessment of thermochemical pathways for sustainable production of high-value chemicals from agroforestry wastes and plastics biorefineries

This study aims to explore cost-effective upgrading strategies for biomass and waste plastics to achieve low-carbon sustainable development, serving as an alternative to traditional petroleum-based production routes for fuels and chemicals. An assessment of products recovered from major agroforestry wastes and disposable plastic packaging bags in the region is conducted through multiple thermochemical pathways. Specifically, the catalytic co-pyrolysis process enables synergistic and efficient conversion of biomass and plastics, yielding high-economic-value derivatives suitable for refining in existing petroleum infrastructure. The core of this work is the synthesis of inexpensive kieselguhr-based beta (KB) zeolites via an in situ depolymerization-recrystallization mechanism, where the dual active sites in metal-zeolite composites exhibit not only strong capture capacity for oxygenated compounds but also promote hydrogen transfer reactions for synergistic deoxidation-aromatization of products. During catalytic co-pyrolysis, KB zeolite effectively refines bio-oils, yielding carbon fractions ranging from C6 to C14, minimal oxygenated fractions, and a monocyclic aromatic hydrocarbons (MAHs) selectivity of up to 74.9 %. Even at a 2:1 biomass-to-plastic ratio, KB zeolite maintains long-term stable catalytic performance, with MAHs selectivity stabilized at 53.6 %.