A study of refractory carbon deposits on Ni/Al2O3 catalysts for dry reforming of methane

When investigating carbonaceous species on a catalyst via temperature-programmed techniques, both the nature of the carbons and the possibility of the catalytic reaction of carbonaceous species should be considered. Here we examined CH4 decomposition (carbon deposition from CH4) and the reverse Boudouard reaction (carbon elimination by CO2) on the Ni/Al2O3 catalyst using sequential temperature-programmed experiments. Carefully considering both the location and characteristics of carbon deposits formed on the Ni/Al2O3 catalyst, we conclude that carbons located on the Al2O3 support are challenging to remove by CO2 regardless of their nature, indicating the importance of support activity in reducing carbon deposits. In this study, the incorporation of cesium (Cs) into Al2O3 shows no effect on the prevention of carbon deposition from CH4 but does show an enhancement of carbon removal via the reverse Boudouard reaction, resulting in less coke formation on the Ni/Cs doped Al2O3 catalyst than the Ni/Al2O3 catalyst by 17 % for the dry reforming of methane.