Chemical looping gasification (CLG) is a promising approach, producing high-purity syngas through redox reactions involving metal oxide oxygen carriers (OCs) in a multi-reactor system. A key challenge in CLG is achieving autothermicity, ensuring that the heat generated in the oxidizer is sufficient to meet the endothermic requirements of biomass gasification in the reducer. As OCs also serve as heat transfer media, high circulation rates are typically required to sustain thermal balance, significantly impacting reactor sizing. One promising solution lies in the use of mixed metal oxide-based OCs, which can lower the endothermic heat requirement of biomass gasification. Although bimetallic systems such as Cu–Fe, Ni–Fe, Mn–Fe, and Co–Fe have been widely studied experimentally, comprehensive system-level thermodynamic analyses to optimize OC composition for reducing OC requirement without compromising syngas quality remain unexplored.
This study presents detailed thermodynamic process simulations with a range of mixed metal oxide-based formulations to quantify their effects on system thermodynamics, OC demand, and overall energy efficiency. Notably, incorporating copper into iron-based OCs significantly lowers the endothermic heat requirement, enabling a reduction in OC demand by approximately 30%. Furthermore, steam co-injection is evaluated as a strategy to enhance char conversion and adjust the syngas composition, yielding an H₂/CO ratio of 1.7, ideal for downstream methanol or liquid fuel synthesis. The insights from this work offer a robust framework for the design of mixed metal oxide-based OCs and contribute to the development of efficient, scalable, and economically viable biomass conversion technologies for a sustainable chemical industry.