Study on the mechanism of CO formation in reverse water gas shift reaction over Cu/SiO2 catalyst by pulse reaction, TPD and TPR

The mechanism of reverse water gas shift reaction over Cu catalyst was studied by pulse reaction with QMS monitoring, temperature programmed desorption (TPD) and temperature programmed reduction (TPR) of Cu/SiO2 catalyst. The reduced and/or oxidized copper offered low catalytic activity for the dissociation of CO2 to CO in the pulse reaction study with 1 ml volume of He/CO2, but the rate of CO formation was significantly enhanced with H-2 participating in the reaction. The TPD spectra of CO2 obtained by feeding H-2/CO2 over copper at 773 K provided strong evidence of the formation of formate at high temperature. The formate derived from the association of H-2 and CO2 is proposed to be the key intermediate for CO production. The formate dissociation mechanism is the major reaction route for CO production.