MgH2/Cu x O Hydrogen Storage Composite with Defect-Rich Surfaces for Carbon Dioxide Hydrogenation

Haipeng Chen; Pei Liu; Jiaqi Li; Yuanjie Wang; Chenxing She; Jinqiang Liu; Linbao Zhang; Qingfeng Yang; Shixue Zhou; Xun Feng

doi:10.1021/acsami.9b11285

MgH₂/Cu _x O Hydrogen Storage Composite with Defect-Rich Surfaces for Carbon Dioxide Hydrogenation

ACS Appl Mater Interfaces. 2019 Aug 28;11(34):31009-31017. doi: 10.1021/acsami.9b11285. Epub 2019 Aug 13.

Authors

Haipeng Chen^{1

2}, Pei Liu², Jiaqi Li¹, Yuanjie Wang¹, Chenxing She¹, Jinqiang Liu¹, Linbao Zhang³, Qingfeng Yang⁴, Shixue Zhou², Xun Feng¹

Affiliations

¹ Henan Key Laboratory of Function-Oriented Porous Materials , Luoyang Normal University , Luoyang 471934 , China.
² State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology , Shandong University of Science and Technology , Qingdao 266590 , China.
³ State Key Laboratory Base of Eco-Chemical Engineering, College of Chemistry and Molecular Engineering , Qingdao University of Science and Technology , Qingdao 266042 , China.
⁴ State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering , Ningxia University , Yinchuan 750021 , China.

PMID: 31368295
DOI: 10.1021/acsami.9b11285

Abstract

Thermal conversion of CO₂ to value-added chemicals is challenging due to the extreme inertness of the CO₂ molecule and the low selectivity of products. We reported a defect-rich MgH₂/Cu_xO hydrogen storage composite from mechanochemical ball-milling for the catalytic hydrogenation of CO₂ to lower olefins. The defect-rich MgH₂/Cu_xO hydrogen storage composite achieves a C₂⁼-C₄⁼ selectivity of 54.8% and a CO₂ conversion of 20.7% at 350 °C under a low H₂/CO₂ ratio of 1:5, which increases the efficiency of H₂ utilization by offering lattice H^- species for hydrogenation. Density functional theory calculations show that the defective structure of MgH₂/Cu_xO can promote CO₂ molecule adsorption and activation, while the electronic structure of MgH₂ is beneficial for offering lattice H^- for CO₂ molecule hydrogenation. The lattice H^- can combine the C site of CO₂ molecule to promote the formation of Mg formate, which can be further hydrogenated to lower olefins under a low H^- concentration. This work for CO₂ conversion by a defect-rich MgH₂/Cu_xO hydrogen storage composite can inspire the catalysts design for the hydrogenation of CO₂ to lower olefins.

Keywords: carbon dioxide; defective structure; hydrogen storage composite; hydrogenation; lower olefins.