Abstract: A high sulfur tolerant Pt catalyst was prepared using a fluorite-type Ce0.8Gd0.2O1.9[KG10x](CGO) oxide as the support that was synthesized by the citric acid sol-gel method. Sulfur tolerance of the catalyst was tested for the steam reforming of isooctane at 750 ℃ and isooctane WHSV of 1.0 h-1 with a steam/carbon molar ratio of 3 using thiophene as the sulfur source. The catalyst calcined at 800 ℃ maintained its activity and selectivity in the entire 100 h test with 300 μg/g or more sulfur, whereas the catalyst calcined at 600 ℃ lost its activity slowly in this course because of both sulfur poisoning and its poor thermal stability. Temperature-programmed reduction and X-ray diffraction analyses, together with comparison of the activity of Pt/CGO with Ni/CGO and Pt/Al2O3, showed that the synergistic effect between CGO oxide and Pt at the interface existed while being enhanced and consolidated with the calcination treatment at 800 ℃, which made Pt immune to sulfur poison and active to convert thiophene sulfur into H2S. In addition, sulfur balance measurements together with diffuse reflectance infrared Fourier transform spectroscopy and microcoulomb titration for surface sulfur-containing species on the used catalyst suggested that thiophene sulfur was completely converted into H2S, probably complying with a redox mechanism.

Key words: platinum, rare earth oxide, steam reforming, isooctane, hydrogen, sulfur tolerance