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The combustion of fossil fuels has led to a large amount of carbon dioxide emissions and increased greenhouse effect. Methanation of carbon dioxide can not only mitigate the greenhouse effect, but also utilize the hydrogen generated by renewable electricity such as wind, solar, tidal energy, and others, which could ameliorate the energy crisis to some extent. Highly efficient catalysts and processes are important to make CO2 methanation practical. Although noble metal catalysts exhibit higher catalytic activity and CH4 selectivity at low temperature, their large-scale industrial applications are limited by the high costs. Ni-based catalysts have attracted extensive attention due to their high activity, low cost, and abundance. At the same time, it is of great importance to study the mechanism of CO2 methanation on Ni-based catalysts in designing high-activity and stability catalysts. Herein, the present review focused on the recent progress of CO2 methanation and the key parameters of catalysts including the essential nature of nickel active sites, supports, promoters, and preparation methods, and elucidated the reaction mechanism on Ni-based catalysts. The design and preparation of catalysts with high activity and stability at low temperature as well as the investigation of the reaction mechanism are important areas that deserve further study.

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Methanol steam reforming was widely used to produce hydrogen for fuel cells. Copper-based catalysts are popular because of its low price and high activity, whereas high selectivity to H 2 is highly expected. Herein, copper-based catalysts with different Zr/Al molar ratios were prepared by the impregnation method. It was found that the 5 wt % Cu/ZrO 2 −8Al 2 O 3 catalyst exhibited high activity with methanol conversion of 84.5%, hydrogen production rate of 98.7 μmol/g cat •s, and the lowest carbon monoxide selectivity of 1.5% because it had the smallest copper particle size, high medium-strong basic site, and high surface (Cu 1+ + Cu 0 ) proportion. The results of in situ FT-IR indicated that formate species might be important intermediates for H 2 production.