Carbon Deposition Characteristics in Thermal Conversion of Methane for Sustainable Fuel

Low-carbon powertrains and sustainable fuels are closely linked as they both aim to reduce carbon emissions and transition away from reliance on fossil fuels. The methane from biogas, biomass, and organic waste can serve as an alternative energy source to traditional fossil fuels. The process of obtaining sustainable fuel (e.g., hydrogen and syngas) from methane is commonly confronted with the problems of carbon deposition on metal oxide. The study of carbon deposition characteristics during methane thermal conversion processes is particularly crucial for low-carbon powertrains. Herein, the carbon deposition on CoAl2O4 and strongly alkali-etched CoAl2O4 ((CoAlO4)-O-v) spinel oxides from the CH4 stage was investigated. We demonstrate that reaction time, calcination temperature, and reaction temperature have no effect on the compositions of carbon deposition, and the material itself plays a crucial role in carbon deposition. The graphitization degree for (CoAlO4)-O-v is lower than that for CoAl2O4. The strong alkali etching in CoAl2O4 only affects contents in different composition carbon deposition. This is mainly attributed to the introduction of Al3+ vacancies by alkali etching, which efficiently tunes the surface electronic structure in CoAl2O4. These findings guide designing efficient and clean low-carbon powertrains, especially in the development of removal carbon deposition technologies and catalysts.