Catalytic combustion of toluene on Pt/Al2O3 and Pd/Al2O3 catalysts with CeO2, CeO2–Y2O3 and La2O3 as coatings

Abstract

CeO2, La2O3, and CeO2–Y2O3 oxides were coated on the surface of spherical granular Al2O3 (3–5 mm) through impregnation method, and proved as better supports of Pd and Pt catalysts. The influences of rare earth metal doping on the adsorption rates of Pd and Pt ions, as well as the catalytic performance, were investigated. Results show that the H2PtCl6·6H2O adsorption rates of the Al2O3 carriers modified by Ce, La, and CeY increase significantly. These rare earth coatings can adsorb almost all H2PtCl6·6H2O in the solution. Compared with Pt/Al2O3 catalyst, Pt/Ce–Al2O3 and Pt/CeY–Al2O3 catalysts have better degradation performance for toluene, and the T90 temperatures are both about 147 °C. According to X-ray photoelectron spectroscopy (XPS) characterization, Pt0 is an important active species for catalytic oxidation reaction of toluene. After CeO2 modification to the conventional Pt/Al2O3 catalyst, the proportion of Pt0 increases from 74.5% to 82.1%. When the Pt0 content in the metal state is improved, the redox activity of the catalyst is promoted correspondingly.