04103nas a2200205 4500008004100000245012200041210006900163260000800232300001600240490000700256520332100263100002903584700001903613700002303632700002403655700002603679700003303705700003003738856012903768 2019 eng d00a Molybdenum carbide catalyst for the reduction of CO2 to CO: surface science aspects by NAPPES and catalysis studies 0 aMolybdenum carbide catalyst for the reduction of CO2 to CO surfa cAUG a12199-122090 v483 a

Carbon dioxide is a greenhouse gas, and needs to be converted into one of the useful feedstocks, such as carbon monoxide and methanol. We demonstrate the reduction of CO2 with H-2 as a reducing agent, via a reverse water gas shift (RWGS) reaction, by using a potential and low cost Mo2C catalyst. Mo2C was evaluated for CO2 hydrogenation at ambient pressure as a function of temperature, and CO2 : H-2 ratio at a gas hourly space velocity (GHSV) of 20 000 h(-1). It is demonstrated that the Mo2C catalyst with 1 : 3 ratio of CO2 : H-2 is highly active (58% CO2 conversion) and selective (62%) towards CO at 723 K at ambient pressure. Both properties (basicity and redox properties) and high catalytic activity observed with Mo2C around 700 K correlate well and indicate a strong synergy among them towards CO2 activation. X-ray diffraction and Raman analysis show that the Mo2C catalyst remains in the beta-Mo2C form before and after the reaction. The mechanistic aspects of the RWGS reaction were determined by near-ambient pressure X-ray photoelectron spectroscopy (NAPXPS) with in situ generated Mo2C from carburization of Mo-metal foil. NAPXPS measurements were carried out at near ambient pressure (0.1 mbar) and various temperatures. Throughout the reaction, no significant changes in the Mo2+ oxidation state (of Mo2C) were observed indicating that the catalyst is highly stable; C and O 1s spectral results indicate the oxycarbide species as an active intermediate for RWGS. A good correlation is observed between catalytic activity from atmospheric pressure reactors and the electronic structure details derived from NAPXPS results, which establishes the structure-activity correlation.

1 aReddy, Kasala, Prabhakar1 aDama, Srikanth1 aMhamane, Nitin, B.1 aGhosalya, Manoj, K.1 aRaja, Thirumalaiswamy1 aSatyanarayana, Chilukuri, V.1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/molybdenum-carbide-catalyst-reduction-co2-co-surface-science-aspects-nappes-and-catalysis