Effects of Metal Promoters (M = Fe, Co, and Cu) in Pt/M_xZr_yO_z Catalysts and Influence of CO₂ and H₂O on the CO Oxidation Activity (PROX): Analysis of Surface Properties After Reaction

In the present paper, the effects of metal promoters (M = Fe, Co, and Cu) in Pt/M_xZr_yO_z catalysts and the influence of CO₂ and H₂O on the CO oxidation activity (PROX) were investigated. To do that, characterizations of catalyst structures and surfaces were performed and reported here. The catalyst Pt/Fe_xZr_yO_z (PFeZ) was the most active at low temperatures among the analyzed ones. The addition of platinum caused strong interaction with the mixed oxide, affecting the structure and the surface composition, blocking basic sites, and thus preventing catalyst deactivation. Particularly, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results evidenced the formation of carboxylate and carbonate species. Besides, the addition of CO₂ and H₂O in the gas feed stream affected the observed CO oxidation results, showing that CO₂ competes with O₂ on metallic sites. Moreover, DRIFTS and temperature-programmed desorption (TPD) analyses suggested the occurrence of OH^– oxidation by CO, leading to the formation of highly reactive compounds that can be easily oxidized.