Enhanced methane conversion in sorption enhanced chemical looping reforming for mid temperature hydrogen production using lithium-based sorbents

Sorption-enhanced chemical looping reforming (SE-CLR) integrates oxygen carrier redox cycling with in-situ CO2 capture to mitigate thermodynamic constraints and product inhibition for mid-temperature H2 production. We develop the SE-CLR approach using particles (∼1.5 mm) of a trace-Cu-doped Fe–Ni/MgAl2O4 oxygen carrier and a Li4SiO4 sorbent co-promoted with K2CO3 and TiO2, operated in cyclic CH4 reduction–sorbent regeneration–air oxidation. At 600 °C, the approach achieved 78.2% CH4 conversion and an H2 production rate of 4.37 mL g−1 min−1, while maintaining 92.3% CO2 capture efficiency and 87.6% H2 purity. Continuous CO2 removal maintains a consistently low CO2 level throughout the reduction step and lowers the apparent activation energy from 34.182 to 20.126 kJ mol−1. The sorbent retains a stable CO2 capacity of approximately 0.22 g CO2 g−1 sorbent over 200 carbonation–decarbonation cycles. Quasi-in-situ XRD indicates a reversible Fe2O3 → Fe3O4 → FeO pathway without Fe0 formation, while in-situ DRIFTS reveals CHx-derived species and carbonate/formate intermediates, evidencing rapid CO2 fixation and robust redox activity. The results demonstrate a promising mid-temperature SE-CLR approach for integrated H2 production with inherent CO2 capture.