CO2 reforming of CH4 over supported Ru catalysts

CO2 reforming of CH4 over Ru supported on eta-Al2O3, TiO2 and high-surface-area carbon black was investigated, and the catalysts were characterized using chemisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and temperature-programmed surface reaction (TPSR). Although CO chemisorption and XRD spectra indicated high Ru dispersions (>50%), H-2 chemisorption was significantly lower. Turnover frequencies for CO2 reforming of CH4 were obtained in the absence of heat and mass transfer effects. These values decreased in the order Ru/TiO2>Ru/Al(2)O(3)much greater than Ru/C, and they were found to depend strongly on the space velocity and hence the percentage of equilibrium conversion. The use of a simple power law kinetic model showed that this dependence is most likely due to a contribution from CO hydrogenation to CH4, which constitutes part of the reverse reaction, thus emphasizing the need to work at low conversions relative to the equilibrium conversion to obtain accurate kinetic data. Correction for this contribution allowed determination of unidirectional forward rates for the CO2/CH4 reforming reaction on Ru. (C) 1999 Academic Press.