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The production of hydrogen from oxidative steam reforming of methanol has been tested for Ce0.9Cu0.1OY catalysts. The catalysts were prepared by deposition–precipitation (dp), coprecipitation (cp), and complexation–combustion (cc) methods. These catalysts were characterized using BET, TEM, X-ray diffraction (XRD), and Raman spectroscopy. A solid solution was formed in the Ce0.9Cu0.1OY prepared by complexation–combustion. The incorporation of Cu atoms into CeO2 lattice leads to an increase of oxygen vacancy. XPS results indicated that the Cu+ is the main Cu species for the Ce0.9Cu0.1OY-cc sample and the synergistic function between Cu2+/Cu+ and Ce4+/Ce3+ occurred in the redox cycle, which is the reason for lower reduction temperatures and improved redox properties as shown in TPR profiles. In the case of the Ce0.9Cu0.1OY-cp and Ce0.9Cu0.1OY-dp samples, most CuO dispersed on the CeO2; the poor interaction between CuO and CeO2 does not affect redox properties of CeO2. Methanol conversions higher than 85% with 90% hydrogen yield were obtained for Ce0.9Cu0.1OY-cc from the oxidative steam reforming of methanol at 240 °C. However, the catalysts prepared by coprecipitation and the deposition–precipitation method showed methanol conversion lower than 30% at 240 °C, and less than 60% even at 360 °C. The high catalytic activity of Ce0.9Cu0.1OY-cc is mainly related to the formation of solid solution and the improved redox properties. [Copyright &y& Elsevier]

Abstract: The structure of the active iron site in Fe/ZSM-35 was investigated by in situ resonance Raman spectroscopy combined with Mössbauer spectroscopy and DFT calculations. In situ UV resonance Raman spectra coupled with 57Fe Mössbauer spectra suggest that the active Fe site for N2O decomposition is an Fe2(μ-O) site, characterized by a Raman band at 875cm−1. In situ visible resonance Raman spectra reveals the formation of an Fe2(μ-O)2 site with a feature Raman band at 730cm−1 upon N2O reacts with the Fe2(μ-O) site. The Raman band intensity at 730cm−1 is decreasing after exposing the Fe2(μ-O)2 site to CH4 due to the formation of methoxide species which mimics the biocatalysis of soluble methane monooxygenase (sMMO). [Copyright &y& Elsevier]

Abstract: The photocatalytic activity in hydrogen production from biomass reforming can be significantly enhanced while keeping ultra-low CO concentration in produced H2 by tuning the anatase–rutile phase structures of Pt/TiO2 photocatalysts. Compared with Pt/P25, the overall photocatalytic activity for the photocatalyst with optimized anatase–rutile structure can be enhanced up to 3–5 times, and the CO concentration in hydrogen can be reduced from several thousands ppm to 5ppm. It is proposed that the anatase–rutile phase structure can not only enhance the charge separation, consequently the activity, but also adjust the surface acid/base property which suppresses the CO formation. [Copyright &y& Elsevier]

Abstract: Combining transient response method, steady-state kinetics, in situ IR, and in situ Raman spectroscopic techniques, the effect of NO on N2O decomposition over Fe/ZSM-5 catalyst was investigated in detail, which reveals that the active sites are bi-nuclear Fe sites. The presence of NO increases the desorption rate of O2 and lowers the apparent activation energy of N2O decomposition. Trace amount of water vapor can lead to the deactivation of the Fe/ZSM-5 catalyst due to the oxidation of the active Fe2+ sites during N2O decomposition. On the other hand, NO treatment causes the regeneration of the inactive Fe sites by releasing O2 at relatively low temperature. For the first time, it was found that a Raman band at 743cm−1, assigned to the bi-nuclear Fe sites, changes accordingly with the deactivation and regeneration of the Fe/ZSM-5 catalyst. The in situ IR spectroscopic study reveals that NO treatment of the deactivated catalyst can remove the hydroxyl groups bound to the inactive Fe3+ species. These results demonstrate that H2O and NO play important roles in the structural transformation between the hydroxylated bi-nuclear Fe3+ sites and the dehydroxylated bi-nuclear Fe2+ sites in Fe/ZSM-5. Our conclusion is that the positive effect of NO on N2O decomposition is due to the dehydroxylation of the hydroxylated bi-nuclear Fe sites facilitated by NO, as well as the enhancement of the O2 desorption rate regulated by NO. [Copyright &y& Elsevier]

The surface sites of MoP/SiO2 catalysts and their evolution under sulfiding conditions were characterized by IR spectroscopy using CO as the probe molecule. The HDS activities of thiophene were measured on the MoP/SiO2 catalyst that was subjected to different sulfidation and reactivation pretreatments. Cus Moδ+ (0<δ&les;2) sites are probed on the surface of fresh MoP/SiO2 by molecularly adsorbed CO, exhibiting a characteristic IR band at 2045 cm−1. The surface of MoP/SiO2 is gradually sulfided in HDS reactions, as revealed by the shift of the IR band at 2045 to ca. 2100 cm−1. Although the surface of a MoP/SiO2 catalyst becomes partially sulfided, the HDS activity tests show that MoP/SiO2 is fairly stable in the initial stage of the HDS reaction, providing further evidence that molybdenum phosphide is a promising catalytic material for industrial HDS reactions. Two kinds of surface sulfur species are formed on the sulfided catalyst: reversibly and irreversibly bonded sulfur species. The MoP/SiO2 catalyst remains stable in the HDS of thiophene because most sulfur species formed under HDS conditions are reversibly bonded on the catalyst surface. A detrimental effect of presulfidation on the HDS activity is observed for the MoP/SiO2 catalyst treated by H2S/H2 at temperatures higher than 623 K, which is ascribed to the formation of a large amount of the irreversibly bonded sulfur species. The irreversibly sulfided catalyst can be completely regenerated by an oxidation and a subsequent reduction under mild conditions. [Copyright &y& Elsevier]