H 2-induced CO adsorption and dissociation over Co/Al 2O 3 catalyst

Abstract

The activation of adsorbed CO is an important step in CO hydrogenation. The results from TPSR of pre-adsorbed CO with H 2 and syngas suggested that the presence of H 2 increased the amount of CO adsorption and accelerated CO dissociation. The H 2 was adsorbed first, and activated to form H * over metal sites, then reacted with carbonaceous species. The oxygen species for CO 2 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 H 2 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.