H2-induced CO adsorption and dissociation over Co/Al2O3 catalyst

The activation of adsorbed CO is an important step in CO hydrogenation. The results from TPSR of pre-adsorbed CO with H₂ and syngas suggested that the presence of H₂ increased the amount of CO adsorption and accelerated CO dissociation. The H₂ was adsorbed first, and activated to form H^* over metal sites, then reacted with carbonaceous species. The oxygen species for CO₂ formation in the presence of hydrogen was mostly OH^*, which reacted with adsorbed CO subsequently via CO^*+OH^* → CO^*₂+H^*; however, the direct CO dissociation was not excluded in CO hydrogenation. The dissociation of C—O bond in the presence of H₂ proceeded by a concerted mechanism, which assisted the Boudourd reaction of adsorbed CO on the surface via CO^*+2H^* → CH^*+OH^*. The formation of the surface species (CH) from adsorbed CO proceeded as indicated with the participation of surface hydrogen, was favored in the initial step of the Fischer-Tropsch synthesis.