Promoting effect of Fe on supported Ni catalysts in CO2 methanation by in situ DRIFTS and DFT study
Huynh, Huong Lan; Zhu, Jie; Zhang, Guanghui; Shen, Yongli; Tucho, Wakshum Mekonnen; Ding, Yi; Yu, Zhixin
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2020-12Metadata
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Huynh, H.L., Zhu, J., Zhang, G., Shen, Y., Tucho, W.M., Ding, Y. & Yu, Z. (2020) Promoting effect of Fe on supported Ni catalysts in CO2 methanation by in situ DRIFTS and DFT study. Journal of Catalysis, 392, 266-277. 10.1016/j.jcat.2020.10.018Abstract
Bimetallic NiFe catalysts have emerged as a promising alternative to the traditional Ni catalysts for CO2 methanation. However, the promoting effect of Fe on the bimetallic catalysts remains ambiguous. In this study, a series of NiFe catalysts derived from hydrotalcite precursors were investigated. In situ x-ray diffraction (XRD) analysis revealed that small NiFe alloy particles were formed and remained stable during reaction. When Fe/Ni = 0.25, the alloy catalysts exhibited the highest CO2 conversion, CH4 selectivity and stability in CO2 methanation at low temperature of 250–350 °C. The in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study indicated that the formate pathway was the most plausible reaction scheme on both Ni and NiFe alloy catalysts, while a moderate addition of Fe facilitated the activation of CO2 via hydrogenation to *HCOO. Density functional theory (DFT) calculations further demonstrated that the overall energy barrier for CH4 formation was lower on the alloy surface.