Catalytic Oxidation of n-Decane, n-Hexane, and Propane over Pt/CeO2 Catalysts

Abstract

Pt species with different chemical states and structures were supported on CeO2 by solution reduction (Pt/CeO2-SR) and wet impregnation (Pt/CeO2-WI) and investigated in catalytic oxidation of n-decane (C10H22), n-hexane (C6H14), and propane (C3H8). Characterization by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, H2-temperature programming reduction, and oxygen temperature-programmed desorption showed that Pt0 and Pt2+ existed on Pt nanoparticles of the Pt/CeO2-SR sample, which promoted redox, oxygen adsorption, and activation. On Pt/CeO2-WI, Pt species were highly dispersed on CeO2 as the Pt-O-Ce structure, in which surface oxygen decreased significantly. The Pt/CeO2-SR catalyst presents high activity in oxidation of C10H22 with a rate of 0.164 μmol min-1 m-2 at 150 °C. The rate increased with oxygen concentration. Moreover, Pt/CeO2-SR presents high stability on feed stream containing 1000 ppm C10H22 at gas hour space velocity = 30,000 h-1 as low as 150 °C for 1800 min. The low activity and stability of Pt/CeO2-WI were probably related to its low availability of surface oxygen. In situ Fourier transform infrared results showed that the adsorption of alkane occurred through the interaction with Ce-OH. The adsorption of C6H14 and C3H8 was much weaker than that of C10H22, which resulted in the decrease in activity for C6H14 and C3H8 oxidation of Pt/CeO2 catalysts.