Theoretical Study on Reactivity of Cu-Based Oxygen Carrier for CO Chemical Looping Combustion

Abstract

The reaction of Cu-based oxygen carrier with CO during chemical looping combustion was studies using density functional theory (DFT) calculations in this paper. It was found that CO2is formed after CO chemically adsorbed onto CuO surface and it exhibits strong localization properties. Energy barrier with regard to the overall reaction is 1.947 eV with overall reaction energy of-3.686 eV, indicating the overall reaction is an exothermic process. As can be figured out from the geometries of the stable structures, after the physical adsorption of CO on CuO surface, 1.947 eV is needed to jump to the transition state, and the nearest distance between CO and the surface is 1.542 Å with bond angle of 155.381°, C-O bond has stretched to 1.151 Å from 1.147 Å. With further interaction between CO and CuO surface, nearly linear structure O-C-O group is formed with bond angle of 179.177° and almost symmetric C-O bond distance, which was thought to be the formation of CO2.