Ni-based catalysts are the most promising catalysts for CO₂ methanation. The development of catalysts with low-temperature activity could bring significant energy and environmental benefits. In this work, the hydrogenation of CO₂ to methane was studied on Ni-M/γ-Al₂O₃ (M = Fe, Co, or Mn) bimetallic catalysts. The optimum reaction was obtained using Ni-Mn/γ-Al₂O₃ (CO₂ conversion: 85%, CH₄ selectivity: 99%, 280 °C). In situ FTIR studies revealed the excellent performance of Ni-Mn/γ-Al₂O₃, which lowers the required reaction temperature. Based on in situ FTIR studies, CO₂ methanation proceeded over three intermediates on the catalysts: bicarbonate → carbonate → formate → methane. The second metal (Co or Mn) promoted the dispersion of both Ni and itself and improved the ability of Ni to crack H₂. And introduced more oxygen vacancies to strengthen the basicity of surrounding O²⁻ on the surface of the catalysts. In effect, the number of carbonate active sites could be increased accordingly, thereby improving the adsorption capacity for CO₂.

Graphic Abstract

中文翻译：

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低温下双金属催化剂上CO 2吸附和甲烷化机理的原位FTIR研究

镍基催化剂是用于CO ₂甲烷化的最有希望的催化剂。具有低温活性的催化剂的开发可以带来巨大的能源和环境效益。在这项工作中，CO的氢化₂到甲烷进行了研究对Ni-M /γ-Al系₂ ö ₃（M =铁，钴，或Mn）的双金属催化剂。使用得到的最佳反应Ni-Mn基/γ-Al系₂ ö ₃（CO ₂转化率：85％，CH ₄选择性：99％，280℃）。在线FTIR研究揭示的Ni-Mn的优良性能/γ-Al系₂ ö ₃，这降低了所需的反应温度。基于原位FTIR研究，CO ₂在催化剂上的三种中间体上进行甲烷化反应：碳酸氢盐→碳酸盐→甲酸盐→甲烷。第二金属（Co或Mn）促进了Ni及其自身的分散，并且提高了Ni裂化H ₂的能力。并引入了更多的氧空位，以增强催化剂表面周围O ^2-的碱性。实际上，碳酸盐活性位点的数目可以相应地增加，从而提高了对CO ₂的吸附能力。

图形摘要