Sustainable co-production of syngas and high-purity H₂ by chemical looping process with TiO₂/Al₂O₃-doped Fe₂O₃ foams as oxygen carrier

To combat climate change, the chemical looping process integrates clean/biofuels for sustainable green energy applications. This study investigates the sustainable co-generation of syngas and high-purity hydrogen (99.999 %) through a two-step chemical looping hydrogen (CLH) process employing novel ternary Fe–Al–Ti oxides foams material as innovative and effective oxygen carriers (FoamOCs). The foams were fabricated via a freeze-casting method that yields an open-cell porous structure, minimizing pressure drop and enhancing gas–solid contact within a fixed-bed reactor. Redox tests were carried out between 675 and 750 °C using bioethanol as the fuel and steam as the oxidant. The Fe2Al3Ti achieved almost complete ethanol conversion (XEtOH ≈ 99.8 %) with high syngas selectivity (SSyngas ≈ 85 %) and an optimal H₂/CO molar ratio of 1.8 at 675 °C. During the oxidation step, pure hydrogen with 99.999 % purity was obtained, demonstrating direct compatibility with PEM fuel cells. The influence of the Al₂O₃/TiO₂ ratio on redox stability was systematically investigated over ten consecutive cycles, revealing that the Fe2Al3Ti composition exhibits the most stable performance with no evidence of carbon accumulation compared to the other formulations. Energy analysis shows that, while the oxidation energy efficiency (EEox) slightly decreases with temperature, the total cycle efficiency (EEcycle) remains nearly constant (97–98 %), confirming that the syngas co-product significantly contributes to overall energy recovery. These findings demonstrate that TiO₂ addition to Fe–Al oxide foams enhances redox stability, oxygen mobility, and carbon resistance, enabling efficient and sustainable co-generation of syngas and ultra-pure hydrogen under mild conditions.