In this work, microwave (MW) irradiation was used to activate Co/Al2O3, Mo/Al2O3, and Co–Mo/Al2O3 catalysts for dry reforming of methane (DRM) reactions.

No abstract

Microwave (MW) methodology has opened up new opportunities for chemical reactions by providing novel routes that are not practical by conventional heating. This paper reports on M–Mo bimetallic catalysts (M = Co or Cu) supported on TiO2 for methane reforming, i.e., dry reforming of methane (DRM) and bi-reforming of methane under MW irradiation. Experimental results displayed outstanding activity of such M–Mo/TiO2 catalysts, on which high reaction efficiency of methane reforming can be sustained at a much lower MW power of 100 W compared to literature results of 200 W. The molar ratio of M/Mo at 1.0 (CoMo1 and CuMo1) displayed the highest catalytic activity for MW-assisted methane reforming under all tested conditions. For DRM, about 81% CH4 and 86% CO2 were converted to syngas with a H2/CO ratio of 0.9 over the CoMo1 catalyst while the CuMo1 catalyst translated 76% CH4 and 62% CO2 into syngas with a H2/CO ratio of 0.8. In the presence of H2O (steam), the H2/CO ratio higher than 2, i.e., 2.2, could be obtained over the Co–Mo catalyst with an input steam-to-methane (S/C) molar ratio of 0.1, while the CuMo1 counterpart required an S/C of 0.2 introduced into the feed to produce such a syngas ratio (H2/CO) of 2.1. The reason behind the excellent performance of the Co–Mo/TiO2 catalyst is the good exposure of the well-defined hexagonal MW absorber. Meanwhile, the formation of a high dielectric layer of MoO2 surrounding active Cu0 can promote the MW absorption of the Cu–Mo/TiO2 catalyst and thereby enhance its catalytic performance. The Co–Mo catalyst exhibited better activity than the Cu–Mo samples given that the magnetic properties of Co particles led to a higher MW absorption ability. Both M–Mo/TiO2 catalysts exhibited brilliant stability under MW irradiation.