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This paper reports the effect of noble metal addition (Ru, Pd) to supported Ni catalysts towards the reaction of CO2 reforming of methane. On the basis of FT-IR spectra of adsorbed CO, H2 chemisorption and TPR measurements it has been proposed that the different behaviour of the Ni-based bimetallic catalysts can be related to different metal–metal interactions occurring on the catalysts. In particular, the strong improvement in the activity and stability observed in the case of ex-nitrate Ni–Ru catalysts has been attributed to an enrichment of the catalyst surface in nickel due to the formation of Ni–Ru clusters with the surface mainly covered by Ni. This leads to an increase in the metallic dispersion of Ni and favours the formation of more reactive intermediate carbonaceous species. [ABSTRACT FROM AUTHOR]

The hydrogenation of CO2 to methane has been investigated over Ru catalysts supported on zeolite (H-ZSM-5) and on silica. Supported Ru catalysts were very active for the hydrogenation of CO2. Ru/ZSM-5 was more selective to methane than Ru/SiO2. On the basis of FT-IR spectra of CO and CO2 adsorbed on the catalysts, it has been suggested that this behaviour can be related to a higher positive polarization of ruthenium on the zeolite. This leads to a weaker Ru–CO bond on the H-ZSM-5-supported sample with a corresponding increase of the hydrogen surface coverage that favours the transformation of the intermediate CO to methane. [ABSTRACT FROM AUTHOR]

Coprecipitated Au/Fe2O3 catalysts used for low-temperature catalytic oxidation of carbon monoxide have been studied by FT-IR spectroscopy of adsorbed CO. The FT-IR results have shown that after preparation and exposure to a CO/O2 mixture gold is present on the surface mainly as Au1+ and Au0 species. It has been found that in the CO oxidation Au1+ is more active and less stable than Au0. [ABSTRACT FROM AUTHOR]