Abstract
Pt species with different chemical states and structures were supported on CeO(2) by solution reduction (Pt/CeO(2)-SR) and wet impregnation (Pt/CeO(2)-WI) and investigated in catalytic oxidation of n-decane (C(10)H(22)), n-hexane (C(6)H(14)), and propane (C(3)H(8)). Characterization by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, H(2)-temperature programming reduction, and oxygen temperature-programmed desorption showed that Pt(0) and Pt(2+) existed on Pt nanoparticles of the Pt/CeO(2)-SR sample, which promoted redox, oxygen adsorption, and activation. On Pt/CeO(2)-WI, Pt species were highly dispersed on CeO(2) as the Pt-O-Ce structure, in which surface oxygen decreased significantly. The Pt/CeO(2)-SR catalyst presents high activity in oxidation of C(10)H(22) with a rate of 0.164 μmol min(-1) m(-2) at 150 °C. The rate increased with oxygen concentration. Moreover, Pt/CeO(2)-SR presents high stability on feed stream containing 1000 ppm C(10)H(22) at gas hour space velocity = 30,000 h(-1) as low as 150 °C for 1800 min. The low activity and stability of Pt/CeO(2)-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 C(6)H(14) and C(3)H(8) was much weaker than that of C(10)H(22), which resulted in the decrease in activity for C(6)H(14) and C(3)H(8) oxidation of Pt/CeO(2) catalysts.