Machine learning-driven optimization of iron-based oxygen carriers for enhanced hydrogen production from biomass chemical looping gasification

• Fe-based OC was optimized by integrating experimental analysis with machine learning. • Fe8Al2 achieved a hydrogen yield of 22.83 mmol/g biomass with a concentration of 44%. • Developed XGBoost model showed the best predictive accuracy. • S/B and Fe content were the most influential variables affecting hydrogen production. Fe-based oxygen carriers (OCs) exhibit significant potential for biomass chemical looping gasification (BCLG) to produce hydrogen. However, variations in OC composition and operating conditions strongly affect BCLG performance. In this study, Fe-based OCs were optimized by integrating experimental results with machine learning (ML) techniques, considering both material composition and operational parameters. Experimental evaluation identified Fe 8 Al 2 as the most effective OC, achieving a hydrogen yield of 22.83 mmol/g biomass. These experimental data were combined with literature datasets to train an XGBoost model, yielding a robust predictive performance (R 2 > 0.824). Interpretable ML analyses using Shapley Additive Explanations (SHAP) and partial dependence plots (PDP) revealed that the steam-to-biomass ratio and Fe content were the most influential factors for hydrogen production. This integrated approach demonstrates a viable pathway for OC optimization by supplementing limited datasets with targeted experimental data, thereby advancing hydrogen production from BCLG.