Anaerobic digestion to acquire biogas is currently the most widely used approach to dispose of vast anthropogenic biowastes. However, effective strategies, except for power generation in the energy sector, to utilize the waste-derived biogas resource are lacking. Herein, we propose a new thermochemical biogas transformation process, catalytic calcium-looping reforming of biogas, to produce syngas with a controllable molar ratio of H2 to CO. In this process, the conventional CH4 dry reforming reaction is decoupled into the separate CH4 dissociation reaction to acquire H2 and reverse Boudouard reaction to acquire CO, respectively. Results showed that the proposed process was able to produce a H2-rich stream at a yield of 175.4mmolH2/gNi with a H2/CO molar ratio of 5.6 at 700 °C, followed by a high-purity CO stream at a yield of 155.4 mmolCO/gNi at 800 °C in one biogas reforming cycle. It is shown that the reaction between CO2 and the carbon species with a graphitic ordering is the rate-determining step of the proposed biogas reforming process. Despite the scope for improvement of process stability, the proposed catalytic calcium-looping reforming of biogas has been experimentally demonstrated to be a promising strategy to inherently control the molar ratio of H2 to CO during syngas production.
- Calcium looping
- H₂/CO molar ratio