Shigang Zhang

Influence of Reaction Conditions on Methanol Synthesis and WGS Reaction in the Syngas-to-DME Process

Abstract A series of CuO-ZnO catalysts (with different Cu/Zn molar ratios) were prepared, and evaluated under the reaction conditions of syngas-to-dimethyl ether (DME) with three sorts of feed gas and different space velocity. The catalysts were characterized by X-ray diffraction (XRD) and temperature-programmed reduction (TPR). The experiment results showed that the reaction conditions of syngas-to-DME process greatly affected the methanol synthesis and WGS reaction. The influence caused by Cu/Zn molar ratio was quite different on the two reactions; increasing of percentage of CO 2 in feed gas was unfavorable for catalyst activity, and also inhibited both reactions; enhancement of reaction space velocity heavily influenced the performance of the catalyst, and the benefits were relatively less for methanol synthesis than for the WGS reaction.

Nitrous oxide decomposition over Co/SBA-15 catalysts: the influence of metal loading, cobalt precursor, and solvent effect

The influence of cobalt loading (10–50 wt-%Co), cobalt precursor, and solvent on the physico-chemical and catalytic properties of mesoporous Co/SBA-15 catalysts for the N2O decomposition reaction has been investigated. Catalysts were characterised by N2 adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), and temperature-programmed reduction (TPR). For Co/SBA-15 catalysts prepared from Co(II) nitrate, the dispersion decreased and the extent of cobalt reduction increased with cobalt loading. A maximum N2O conversion was found for the sample with ca. 30 wt-% Co loading. At similar cobalt loading (ca. 30 wt-%), a low dispersion and a stronger cobalt–support interaction leading to the formation of low reducible cobalt silicates was observed for Co/SBA-15 samples prepared from acetate precursors as compared to that derived from cobalt(II) nitrate, as evidenced by TPR. The former catalysts showed a low N2O decomposition activity. Moreover, at every Co loadings, the catalysts prepared in water exhibited much higher activities than those prepared in ethanol solvent, which could be related to the low reducibility of cobalt species in the latter catalysts. Finally, at comparable Co loading Co/SBA-15 catalysts (nitrate precursor) were more active than a Co/SiO2 and Co/Al2O3 sample.