Nature of support plays vital roles in H2O promoted CO oxidation over Pt catalysts

Pt nanoparticle catalysts supported on a series of TiO2-SiO2 composites with different molar ratios were prepared, characterized, and their CO oxidation activities were evaluated under dry and humid condi-tions. Among the catalysts, Pt/1Ti-3Si showed the best performance under both conditions and potentials for future industrial applications. H218O experiments were designed and the CO2 composition was calcu-lated to quantify the promotion effect of H2O, which was highly correlated with the concentration of H2O and Ti-Si ratio. The XRD, XPS and BET results revealed that the defects on the supports inhibited phase transformation and lattice growth for anatase TiO2. These defects also led to an increase in the number of acid sites on Pt/TiO2-SiO2. The TEM, EDS mapping, and CO chemosorption results indicated that metal-lic Pt0 particles were formed, which was beneficial for CO oxidation during reaction. It was found that the generation of OH from H2O dissociation and the desorption of OH on TiO2 were much easier than those on SiO2, illustrating that the H2O promotion effect could be controlled by regulating the nature of support. The mechanism of H2O promotion was proposed by experimental and theoretical methods, which con-firmed the carboxyl intermediate pathway rather than the formate pathway.(c) 2022 Elsevier Inc. All rights reserved