Fuel-assisted thermochemical CO production from CO2 using Co- and Ni-doped LaSrMn-based perovskite oxides

Perovskite oxygen carriers are widely studied for solar-driven thermochemical CO₂ splitting at >1300°C, yet their behaviour under fuel-assisted chemical looping conditions remains poorly understood. Here, two benchmark La–Sr–Mn perovskites La₀.₇Sr₀.₃Mn₀.₆₅Co₀.₃₅O₃ (LSMC) and La₀.₇Sr₀.₃Mn₀.₈Ni₀.₂O₃ (LSMN) previously optimised for two-step solar cycling, are systematically evaluated for fuel-assisted chemical looping CO₂ splitting. Fuel-assisted reduction with H₂ and CO/CO 2 -diluted gas (e.g. blast furnace gases) enables deep lattice activation at 700–900°C, achieving stabilised oxygen transfer capacities of 3.36 mmol O g⁻¹ (LSMC) and 2.85 mmol O g⁻¹ (LSMN). Subsequent CO₂ splitting at 900°C sustains >99% CO₂ conversion, yielding total CO productions of 0.97 mmol CO g⁻¹ (LSMC) and 0.87 mmol CO g⁻¹ (LSMN) with effective production rates of 0.22–0.23 mmol CO g⁻¹ min⁻¹, exceeding reported two-step solar thermochemical cycling rates by more than threefold. Redox stability reveals a trade-off between oxygen mobility and lattice robustness. Over 40 thermogravimetric cycles, LSMN exhibits a larger capacity loss (−11.3%) than LSMC (−2.6%), while packed-bed operation without hydrocarbons results in minimal OTC degradation (<1.6%) for both materials. CH₄ exposure induces pronounced degradation in LSMC due to over-reduction and cation exsolution. These results demonstrate that fuel-assisted chemical looping substantially expands the performance envelope of perovskite oxygen carriers beyond solar-only operation, while defining durability limits critical for scalable CO₂-to-CO conversion.