Microwave heating-assisted chemical looping dry reforming of methane

Chemical looping dry reforming of methane (CLDRM) offers a sustainable pathway to convert methane (CH4) and carbon dioxide (CO2) to syngas, i.e., a mixture of hydrogen (H2) and carbon monoxide (CO). However, carbon deposition caused by high gas temperature remains a crucial challenge for the CLDRM. We proposed microwave (MW) heating-assisted CLDRM to leverage the selective heating feature of MWs to create a thermal gradient between solid and gas phases. This thermal gradient, i.e., a higher solid temperature than the gas temperature, can promote desired reduction and oxidation (redox) reactions, while suppressing undesired gas phase reactions, in particular, CH4 decomposition. At bulk temperature of 800 °C, the MW heating-assisted CLDRM achieved a maximum CH4 conversion of 97% and H2/CO ratio of around 2. Compared to the conventionally heated CLDRM, the MW heating increased the redox extents of magnetite (the oxygen carrier) by 2.5 and 1.5 times, respectively, and suppressed carbon deposition.