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Highly Selective and Efficient Reduction of CO₂ to Methane by Activated Alkaline Earth Metal Hydrides without a Catalyst

Zhao, Juan, Wei, Yin-Fan, Cai, Yue-Ling, Wang, Long-Zheng, Xie, Ju, Teng, Yun-Lei, Zhu, Wei, Shen, Ming, Dong, Bao-Xia
ACS sustainable chemistry & engineering 2019 v.7 no.5 pp. 4831-4841
alkaline earth metals, carbon dioxide, catalysts, clean energy, hydrides, methane, methane production, temperature
Achieving highly selective and efficient reduction of carbon dioxide into methane will significantly affect the resolution of two of the current crucial issues facing humanity, namely environmental problems due to excess CO₂ and the increasing demand for clean energy. In this paper, the thermochemical reduction of carbon dioxide into methane by the activated alkaline-earth metal hydrides was reported. The results of the correlational experiments show that the reduction of carbon dioxide by the activated nanosized alkaline-earth metal hydrides is highly selective and efficient in the absence of a catalyst under moderate conditions. Only a hydrocarbon species, namely methane, is produced, and the methane yield can reach 88% for the reactions between CaH₂ and carbon dioxide. The mole percentage and yield of CH₄ in the gas-state products depend largely on the type of alkaline-earth metal hydride, reaction temperature, and reaction time.