A series of novel Ni/CeO2-Al2O3composite catalysts were synthesized by one-step citric acid complex method. The as-synthesized catalysts were characterized by N2physical adsorption/desorption, X-ray diffraction(XRD), Fourier transform infrared(FT-IR) spectroscopy, hydrogen temperature-programmed reduction(H2-TPR), X-ray photoelectron spectroscopy(XPS) and thermogravimetry analysis(TGA). The effects of nickel content, calcination and reaction temperatures, gas hourly space velocity(GHSV) and inert gas dilution of N2on their performance of catalytic partial oxidation of methane(CPOM) were investigated. Catalytic activity test results show that the highest methane conversion(>85%), the best selectivities to carbon monoxide(>87%) and to hydrogen(>95%), the excellent stability and perfect H2/CO ratio(2.0) can be obtained over Ni/CeO2-Al2O3with 8 wt% Ni content calcined at 700 ℃ under the reaction condition of 750 ℃, CH4/O2ratio of 2 : 1 and gas hourly space velocity of 12000 mL h-1 g-1. Characterization results show that the good catalytic performance of this composite catalyst can be contributed to its large specific surface area(～108 m2 g-1), small crystallite size, easy reducibility and low coking rate.
A series of novel Ag Cl/Ag_2CO_3 heterostructured photocatalysts with different Ag Cl contents(5 wt%,10 wt%, 20 wt%, and 30 wt%) were prepared by facile coprecipitation method at room temperature. The resulting products were characterized by powder X-ray diffraction(XRD), scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS), and ultraviolet–visible diffuse reflectance spectroscopy(UV–Vis DRS), respectively. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of methyl orange(MO) under UV light irradiation. With the optimal Ag Cl content of 20 wt%, the Ag Cl/Ag_2CO_3 composite exhibits the greatest enhancement in photocatalytic degradation efficiency. Its first-order reaction rate constant(0.67 h-1) is5.2 times faster than that of Ag_2CO_3(0.13 h-1), and 16.8times faster than that of Ag Cl(0.04 h-1). The formation of Ag Cl/Ag_2CO_3 heterostructure could effectively suppress the recombination of the photo-generated electron and hole, resulting in an increase in photocatalytic activity.
