Methanation of carbon dioxide over Ni–M/ZrO2 (M = Fe, Co, Cu) catalysts: Effect of addition of a second metal

• The addition of Fe enhanced catalytic activity of Ni/ZrO2 in CO2 methanation.
• The addition of Fe improved the dispersion and reduction degree of Ni.
• Fe2 + enhanced the partial reduction of zirconia.
• The above effects further promoted adsorption and dissociation of H2 and CO2.

Ni/ZrO2 catalysts with an added second metal were prepared by impregnation method and used in CO2 methanation. X-ray diffraction, hydrogen temperature programmed reduction, hydrogen temperature programmed desorption, X-ray photoelectron spectroscopy, and in situ infrared spectroscopy measurements were taken to characterize the surface and bulk properties of the catalysts. Compared with Co and Cu, Fe could efficiently enhance the catalytic activity of Ni/ZrO2 in CO2 methanation at low temperatures. The optimal amount of Fe was 3 wt.%. CO2 methanation over Ni–Fe/ZrO2 catalysts may proceed through dissociation of CO2 into CO and subsequent reaction of CO with hydrogen to generate methane. Addition of Fe not only can improve the dispersion and degree of reduction of Ni, but also can enhance the partial reduction of zirconia. These effects further promote adsorption and dissociation of H2 and CO2, thus enhancing the activity of the catalyst in CO2 methanation.

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