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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/12684

Title: A DFT investigation of the mechanisms of CO2 and CO methanation on Fe (111)
Authors: Kwawu, Caroline R.
Aniagyei, Albert
Tia, Richard
Adei, Evans
Keywords: Spin-polarized DFT-GGA
CO2 methanation
CO methanation
Methanol formation
Reaction mechanism
Issue Date: 10-Jan-2020
Publisher: Springer
Citation: Materials for Renewable and Sustainable Energy (2020) 9:4 https://doi.org/10.1007/s40243-020-0164-x
Abstract: Insight into the detailed mechanism of the Sabatier reaction on iron is essential for the design of cheap, environmentally benign, efficient and selective catalytic surfaces for CO2 reduction. Earlier attempts to unravel the mechanism of CO2 reduc-tion on pure metals including inexpensive metals focused on Ni and Cu; however, the detailed mechanism of CO2 reduction on iron is not yet known. We have, thus, explored with spin-polarized density functional theory calculations the relative stabilities of intermediates and kinetic barriers associated with methanation of CO2 via the CO and non-CO pathways on the Fe (111) surface. Through the non-CO (formate) pathway, a dihydride CO2 species (H2CO2), which decomposes to aldehyde (CHO), is further hydrogenated into methoxy, methanol and then methane. Through the CO pathway, it is observed that the CO species formed from dihydroxycarbene is not favorably decomposed into carbide (both thermodynamically and kinetically challenging) but CO undergoes associative hydrogenation to form CH2OH which decomposes into CH2, leading to methane formation. Our results show that the transformation of CO2 to methane proceeds via the CO pathway, since the barriers leading to alkoxy transformation into methane are high via the non-CO pathway. Methanol formation is more favored via the non-CO pathway. Iron (111) shows selectivity towards CO methanation over CO2 methanation due to differences in the rate-determining steps, i.e., 91.6 kJ mol−1 and 146.2 kJ mol−1, respectively.
Description: An article published by Springer and also available at https://doi.org/10.1007/s40243-020-0164-x
URI: http://hdl.handle.net/123456789/12684
Appears in Collections:College of Science

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