Abstract: Sulfur-tolerant Pt/Ce0.8Gd0.2O1.9 (Pt/CGO) and Pt/Al2O3 catalysts were characterized by means of in situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) for adsorption of CO and co-adsorption of CO with thiophene and hydrogen sulfide. CO adsorbed on the surface of 1.6%Pt/CGO-800 catalyst (calcined at 800 ℃) showed an IR peak at 2104cm-1, which is 34 cm-1higher than that (2070cm-1) on the surface of 1.6%Pt/Al2O3-500 catalyst. CO adsorbed on the surface of 1.6%Pt/CGO-600 catalyst exhibited two IR peaks, a main peak likewise at 2108cm-1 and a shoulder peak at 2085cm-1. For 1.6%Pt/CGO-800, co-adsorbed thiophene caused a shift of the CO peak from 2104cm-1to 2090cm-1. For 1.6%Pt/CGO-600, the main peak was shifted from 2108cm-1 to 2096cm-1 with a slight reduction of peak intensity, and the shoulder CO peak at2085cm-1disappeared. For 1.6%Pt/Al2O3-500, after thiophene was co-adsorbed, the CO peak at 2070cm-1 shifted about 30 cm-1to a lower wavenumbers and the peak intensity significantly decreased. Subsequently adsorbed H2S only caused a 2-4 cm-1red shift of CO peaks at 2104cm-1 for 1.6%Pt/CGO-800 and 2108cm-1 for 1.6%Pt/CGO-600 but led to a complete loss of the CO adsorption ability of 1.6%Pt/Al2O3-500. These results indicated that strong electron-deficient Pt sites that were resistant to sulfur poison were formed on the Pt/CGO catalysts and calcination at 800 ℃ of Pt/CGO resulted in the formation of unique Pt sites that had the highest sulfur tolerance.

Key words: in situ diffuse reflectance infrared fourier transform spectroscopy, sulfur tolerance, platinum catalyst, hydrogen production, rare earth composite oxide