The Mechanism for the Selective Oxidation of CO Enhanced by H2O on a Novel PROC Catalyst

Abstract

Preferential oxidation (PROX) reaction of CO in H2 catalyzed by a new catalyst of FeO x /Pt/TiO2 (Fe: Pt: TiO2 = 100: 1: 100) was studied by dynamic in-situ DRIFT-IR spectroscopy. The oxidation of CO is markedly enhanced by H2 and H2O, and the enhancement by H2/D2 and H2O/D2O takes a common hydrogen isotope. Dynamics of DRIFT-IR spectroscopy suggests that the oxidation of CO with O2 in the absence of H2 proceeds via bicarbonate intermediate. In contrast, rapid oxidation of CO in the presence of H2 proceeds via HCOO intermediate and the subsequent oxidation of HCOO by the reaction with OH, that is, CO + OH→ HCOO and HCOO + OH → CO2 + H2O. The latter reaction is a rate determining step being responsible for a common hydrogen isotope effect by H2/D2 and H2O/D2O.