CO2 reforming of CH4 over supported Pt catalysts

The kinetics of CO(2) reforming of CH(4) were studied over Pt supported on TiO(2), ZrO(2), Cr(2)O(3), and SiO(2), and the catalysts were characterized using chemisorption, X-ray diffraction, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), temperature-programmed hydrogenation (TPH), and temperature-programmed surface reaction. Although the Pt/SiO(2) and Pt/Cr(2)O(3) catalysts deactivated significantly within 5 and 15 h onstream, respectively, the Pt/ZrO(2) and Pt/TiO(2) catalysts exhibited much higher stability even after 80 to 100 h onstream. TPH results with used catalysts showed that both Pt/ZrO(2) and Pt/TiO(2) have suppressed carbon deposition under reaction conditions. H(2) and CO chemisorption as well as DRIFTS provided evidence of metal-support interactions in the Pt/TiO(2) catalyst and indicated that large ensembles of Pt atoms, active for carbon deposition, are deactivated or destroyed by the presence of mobile TiO(x) species. Activities for CO formation and CH(4) consumption on a turnover frequency basis were five times greater on Pt/TiO(2) compared with the other catalysts, suggesting that active sites for reforming are created in the Pt-TiO(x) interfacial region. The kinetic behavior was explained well by a kinetic model recently proposed for supported Ni. (C) 1998 Academic Press.