Hydrogen activation on aluminium-doped magnesium hydride surface for methanation of carbon dioxide

• Published in: Applied surface science Vol. 515; p. 146038
• Main Authors: Chen, Haipeng, Ma, Ningning, Cheng, Chunhua, Zhang, Hui, Yuan, Weiwei, Liu, Pei, Feng, Xun, Liu, Jinqiang, Yang, Qingfeng, Zhou, Shixue
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.06.2020
• Subjects: Carbon dioxide; Hydrogen activation; Hydrogenation; Lattice hydrogen; Methanation; Methanation; Lattice hydrogen; Hydrogen activation; Hydrogenation; Carbon dioxide
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.146038

[Display omitted] •The activation of H2 is considered in CO2 conversion to CH4.•H2 is dissociated on the Al-doped MgH2 surface to offer lattice H− for CO2 methanation.•Al-doping can weaken the MgH bond by the formation of AlH bond.•Lattice H− can combine with the C atom of CO2 to promote the Mg formate formation. Traditional catalysts for thermal hydrogenation of CO2 mainly focus on the catalytic activation of CO2 molecule, while the activation of H2 is often neglected. Herein, we report an Al-doped MgH2 nano-catalyst producing negative lattice H− as hydrogen source for CO2 hydrogenation. The Al-doped MgH2 nano-catalyst is synthesized with a reactive ball-milling method equipped with Al-based milling balls to dope Al on MgH2 surface. The surface doping of Al promotes the dissociation of H2 to lattice H− and helps the catalyst to achieve 88.4% CH4 selectivity and 27.1% CO2 conversion under H2/CO2 ratio 5/1 at 320 °C and 1.0 MPa. The atomic-doped-Al weakens the MgH bond and improves electron transfer on MgH2 surface, by which gives the lattice H− a high reactivity for CO2 hydrogenation. The delocalized large π bond of CO2 molecule is weakened by the combination of the lattice H− to the C atom of CO2 molecule, which promotes the formation of Mg formate, significantly influencing the hydrogenation route.