Critical review on the production of quality-enhanced bio-oil from co-pyrolysis of lignocellulosic biomass and common plastics waste

The pressing challenges facing modern society, such as pollution from plastic waste, climate change driven by greenhouse gas emissions, and the depletion of fossil fuel resources, demand urgent and sustainable solutions. One promising approach is the thermal decomposition of plastic waste and biomass. Recent advancements in pyrolysis technology have led to the development of co-pyrolysis, which enhances the process by inducing a synergistic effect between raw materials, improving both the quality and quantity of the desired products. This study provides a comprehensive review of the latest developments in co-pyrolysis of lignocellulosic biomass with various plastics, including high-density polyethylene, low-density polyethylene, polypropylene, polyethylene terephthalate, polystyrene and polyvinyl chloride. The characteristics of the raw materials, including organic and inorganic components, calorific value, and the hydrogen-to-carbon ratio—are examined to identify the optimal feedstocks for producing high-quality products. This review also delves into the mechanisms and product distribution of pyrolysis and co-pyrolysis of feedstocks, exploring the factors that influence process optimization, such as operating parameters, reactor types, feedstock mixing ratios, and the use of catalysts. Reactions such as polymerization, dehydration, deoxygenation, hydrodeoxygenation, hydrogenation, aromatization, and condensation play vital roles in improving the yield and quality of the final products, and catalysts can accelerate these processes. The primary objective of this review is to deepen the understanding of co-pyrolysis and its potential as a sustainable solution to global environmental challenges.