Calcium-Looping Dry Reforming Enhances Biogas Conversion to Syngas with Simultaneous CO₂ Abatement

Conversion of biogas into syngas expands its application scope from fuel for power generation to industrial feedstock for the synthesis of value-added chemicals; however, it is restricted to the limited CH4 conversion due to the mismatch between CH4/CO2 feeding ratios of biogas and the stoichiometry of the CH4 dry reforming reaction. Herein, we proposed a novel calcium-looping biogas dry reforming process (CaL-BR) to supplement exogenous CO2 into biogas in situ by the introduction of a CaO-based carbon-carrying cycle. Using the facilely prepared composite material CaO–Ni/Al2O3_1 for CaL-BR at 750 °C, the CH4 conversion was over 65% and 16.4% higher than that of conventional biogas reforming, enabling the syngas yield to reach as high as 136.7 mmol/g. Importantly, the proposed process exhibited superior cyclic stability with a decay in the biogas reforming performance below 3% over 20 CaL-BR cycles under typical biogas CH4/CO2 feeding ratios, which was confirmed to be a consequence of the suppressed sintering of Ni particles and carbon deposition. The proposed CaL-BR process offered a promising option to make the best of the CH4 resource in biogas with the simultaneous capture and conversion of CO2.