Carbon-confined magnesium hydride nano-lamellae for catalytic hydrogenation of carbon dioxide to lower olefins

• Published in: Journal of catalysis 2019-11, Vol.379, p.121-128
• Main Authors: Chen, Haipeng, Liu, Jinqiang, Liu, Pei, Wang, Yajing, Xiao, Haiyan, Yang, Qingfeng, Feng, Xun, Zhou, Shixue
• Format: Article
• Language: English
• Subjects: Carbon confinement; Carbon dioxide; Hydrogenation; Lower olefins; Magnesium hydride
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2019.09.022

[Display omitted] •CO2 is directly converted to lower olefins by a carbon-confined MgH2 nano-lamellae.•Carbon confines MgH2 in nanoscale to improve the reactivity for CO2 hydrogenation.•Carbon-confined MgH2 nano-lamellae offers solid hydrogen for CO2 hydrogenation.•Solid hydrogen for CO2 hydrogenation increases the efficiency of hydrogen utilization. The direct production of lower olefins from CO2 hydrogenation has attracted enormous attention for its significant roles in mitigating CO2 emissions and developing green chemistry. For the first time, we report carbon-confined MgH2 nano-lamellae storing solid hydrogen for hydrogenation of CO2 to lower olefins. The carbon-confined MgH2 nano-lamellae achieve high selectivity to C2= - C4= species under low H2/CO2 ratios, which can significantly increase the efficiency of H2 utilization comparing with traditional methods. DFT calculations show that the lattice H− of MgH2 can combine to the C site of CO2 molecule to form Mg formate, while the aromatic H+ of carbon can combine to the O site of CO2 molecule to form H2O, which both promote the CO2 hydrogenation. The high selectivity of lower olefins is ascribed to the low concentration of solid hydrogen under low H2/CO2 ratios, by which the Mg formate can be further hydrogenated to lower olefins before fully hydrogenated to saturated hydrocarbons. This novel conversion method for CO2-to-olefins by carbon-confined MgH2 nano-lamellae can inspire the catalysts design for CO2 to value-added chemicals.