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Ru is considered as an effective active species for N2O decomposition; however, there is disagreement about which ruthenium species is key for catalytic activity. In order to understand the role of Ru species in N2O decomposition, Ru/Al2O3 (Ru/Al2O3-H2, Ru/Al2O3-NaBH4, Ru/Al2O3-air) catalysts with different ratios of metallic Ru were prepared and evaluated for their catalytic activities. Various characterizations, especially in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), were applied to investigate the relationship between activity and different Ru species. The results indicate that the N2O conversion displayed a linear relationship with the amount of metallic Ru. The DRIFTS results of adsorption for N2O show that metallic Ru was the active site. The catalytic processes are put forward based on metallic Ru species. The deactivation with increasing times used is due to the decrease in the amount of metallic Ru and agglomerates of Ru particles on the surface of catalysts. [ABSTRACT FROM AUTHOR]

In this work, the activity of xCuO-Ce0.9Zr0.1O2 catalysts for the reaction of NO + CO was investigated. Especially, in situ DRIFTS was applied to investigate the surface species under the adsorption of NO and/or CO and the reaction of NO and CO to understand the key intermediates species and reaction process of NO + CO. The results suggest that the copper oxide species are well dispersed on the surface of the catalysts, which can be easily reduced to form Cu+ species. The Cu+ species are proposed to be important activity species. The results of this work also suggest that N2 O22- is likely an intermediate species that plays an important role in NO reduction by CO. Thus, more Cu+ and highly dispersed copper oxide species are expected to be beneficial for the reaction of CO + NO over the xCuO-Ce0.9Zr0.1O2 catalysts. [ABSTRACT FROM AUTHOR]

The vanadium oxide/reduced graphene oxide (VOx/RGO) composites have been prepared by a simple solvothermal method with the assistance of cationic surfactant cetyltrimethylammonium bromide (CTAB). The microstructure and morphology of the resultant VOx/RGO composites have been well characterized. The VOx nanoparticles are highly dispersed on the RGO sheets with a particle size of about 25 nm. When used as hydroxylation catalysts, the VOx/RGO composites are more efficient than individual RGO and vanadium oxide catalysts. The enhanced catalytic performance may be related to not only the well dispersed VOx active species, but also the hydrophobic surface and huge π-electron system of RGO for the adsorption and activation of benzene. In addition, the effects of calcination conditions on the microstructure and catalytic properties of VOx/RGO composites have also been investigated. The uniform VOx nanoparticles on the separated RGO sheets show highly efficient catalytic performance, while the formation of aggregated HxV2O5 and bulk V2O5 species along with the destruction of RGO sheets are poor for the hydroxylation of benzene. Up to 17.4% yield of phenol is achieved under the optimized catalytic reaction conditions. [ABSTRACT FROM AUTHOR]