Chemical Looping Gasification of Plastics toward Hydrogen-Rich Syngas: A Review of Oxygen Carrier Design and Process Optimization

In the dual pursuit of achieving the global goal of carbon neutrality and curbing plastic pollution, chemical looping gasification (CLG) technology has emerged a key approach to integrate plastic waste recycling with H2-rich syngas production. This review systematically examines and compares the design strategy (support properties, active metal modification and bimetallic synergy) of oxygen carrier (OC) and the optimization progress of key process parameters (temperature, reactor staging and co-gasification of biomass) in the production of H2-rich syngas from plastic CLG. The findings demonstrate that support optimization and metal synergy can significantly regulate the syngas yield and its H2/CO ratio, while improving the cycle stability of OCs. Temperature and segmented CLG significantly improves the conversion rate and achieve flexible control of the H2/CO ratio. CLG of biomass and plastics can improve the yield and quality of H2-rich synthesis due to the complementary hydrocarbon and the coordinated conversion of tar. However, most studies at present use model plastics as fuel, which highlights the key shortcomings in understanding actual plastic waste, impurities, long-term CLG stability, and systematic economic evaluation. This review aims to provide guidance for the development of stable and selective OC systems and the optimization of CLG systems to achieve sustainable energy conversion of plastic waste.