Abstract
The influence of Ce and W promoters on the performance of alumina-supported nickel catalysts in the CO2 methanation reaction was investigated. The catalysts were obtained by the co-impregnation method. Nitrogen low-temperature adsorption, temperature-programmed reduction, hydrogen desorption, transmission electron microscopy, X-ray diffraction, and photoelectron spectroscopy studies were used for catalyst characterization. An introduction of Ce and W promoters (1–5 wt %) led to the decrease in mean Ni crystallite size. Gradual increase in the active surface area was observed only for Ce-promoted catalysts. The increase in CO2 conversion in methanation reaction at low-reaction temperatures carried out over Ce-promoted catalysts was attributed to the increase in the active surface area and changes in the redox properties. The introduction of small amounts of tungsten led to an increase in the activity of catalysts, although a decrease in the active surface area was observed. Quasi in situ XPS studies revealed changes in the oxidation state of tungsten under CO2 methanation reaction conditions, indicating the participation of redox promoter changes in the course of surface reactions, leading to an improvement in the activity of the catalyst.
Highlights
Enrique García-BordejéMitigation of climate change affected by emission of greenhouse gases belongs to the most important challenges [1]
Temperature-programmed reduction studies indicated an increase in reducibility of catalysts with an increase in Ce content
Chemisorption and temperature-programmed hydrogen desorption studies indicated that an active surface area of catalysts was increased with an increase in Ce content and decreased with an increase in W content
Summary
Mitigation of climate change affected by emission of greenhouse gases belongs to the most important challenges [1]. It requires multi-directional measures including, capture, storage, or utilization of carbon dioxide. The idea of converting captured CO2 into methane using hydrogen produced by renewable energy is currently receiving widespread attention [2,3]. This concept can be used in a variety of economic sectors, including energy and chemical production, as well as the agro-food industry. Hydrogenation of carbon dioxide can be conducted towards valuable products such as methanol, dimethyl ether, or formic acid, its conversion to methane (reaction 1) is currently the most mature technology and is likely to find wide application [4,5,6].
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