Palladium catalysts are supported on TiO2, ZrO2, A12O3, Zro.sAlo.501.75 and TiO2-Zro.sAlo.501.75 prepared by co-precipitation method, re- spectively. Catalytic activities for methane and CO oxidation are evaluated in ...Palladium catalysts are supported on TiO2, ZrO2, A12O3, Zro.sAlo.501.75 and TiO2-Zro.sAlo.501.75 prepared by co-precipitation method, re- spectively. Catalytic activities for methane and CO oxidation are evaluated in a gas mixture that simulated the exhaust from lean-burn natural gas vehicles （NGVs）. Pd/TiO2-Zro.sAlo.501.75 performs the best catalytic activity among the tested five catalysts. For CH4, the light-off temperature （Tso） is 254 ℃, and the complete conversion temperature （Tgo） is 280 ℃; for CO, Tso is 84 ℃, and Tgo was 96 ℃. Various techniques, including N2 adsorption-desorption, X-ray diffraction （XRD）, H2-temperature-programmed reduction （H2-TPR）, X-ray photoelec- tron spectroscopy （XPS）, and scanning electron microscopy （SEM） are employed to characterize the effect of supports on the physicochemical properties of prepared catalysts. N2 adsorption-desorption and SEM show that TiO2-Zro.5Al0.501.75 expresses uniform nano-particles and large meso-pore diameters of 26 nm. H2-TPR and XRD indicate that PdO is well dispersed on the supports and strongly interacted with each other. The results of XPS show that the electron density around PdO and the proportion of active oxygen on TiO2-Zro.sAl0.501.75 are maxima among the five supports.展开更多
A series of CexZr1-xO2(0 B x B 1)with different molar ratios of Ce/Zr were syhthesized via coprecipitation method,and Fe2O3-WO3/CexZr1-xO2monolithic catalysts were prepared for selective catalytic reduction of nitroge...A series of CexZr1-xO2(0 B x B 1)with different molar ratios of Ce/Zr were syhthesized via coprecipitation method,and Fe2O3-WO3/CexZr1-xO2monolithic catalysts were prepared for selective catalytic reduction of nitrogen oxides by ammonia(NH3-SCR).The structural properties and redox behavior of the catalysts were comprehensively characterized by N2physisorption,X-ray diffraction(XRD),X-ray photoelectron spectra(XPS),H2-temperature programmed reduction(H2-TPR)and activity measurement for NH3-SCR.The results showed that the NH3-SCR activities of the catalysts were gradually enhanced by increasing the molar ratios of Ce/Zr,especially the lowtemperature catalytic activity and the reaction temperature window.Fe2O3-WO3/Ce0.68Zr0.32O2monolithic catalyst presented the best NH3-SCR activity among the investigated catalysts,more than 90%NOxcould be removed in the temperature range of 247–454°C on the catalyst under the gas hourly space velocities of 30,000 h-1.And it always held more than 99%N2selectivity and less than 20 ppm(1 ppm=10-6L/L)N2O generation concentration between 200 and500°C,the catalyst also displayed its strong resistance of H2O and SO2.Good textural and structural properties,more surface Fe,Ce and active oxygen were together contributed to the excellent NH3-SCR performance of Fe2O3-WO3/Ce0.68Zr0.32O2catalyst.展开更多
基金supported by the National Natural Science Foundation of China(21173153)
文摘Palladium catalysts are supported on TiO2, ZrO2, A12O3, Zro.sAlo.501.75 and TiO2-Zro.sAlo.501.75 prepared by co-precipitation method, re- spectively. Catalytic activities for methane and CO oxidation are evaluated in a gas mixture that simulated the exhaust from lean-burn natural gas vehicles （NGVs）. Pd/TiO2-Zro.sAlo.501.75 performs the best catalytic activity among the tested five catalysts. For CH4, the light-off temperature （Tso） is 254 ℃, and the complete conversion temperature （Tgo） is 280 ℃; for CO, Tso is 84 ℃, and Tgo was 96 ℃. Various techniques, including N2 adsorption-desorption, X-ray diffraction （XRD）, H2-temperature-programmed reduction （H2-TPR）, X-ray photoelec- tron spectroscopy （XPS）, and scanning electron microscopy （SEM） are employed to characterize the effect of supports on the physicochemical properties of prepared catalysts. N2 adsorption-desorption and SEM show that TiO2-Zro.5Al0.501.75 expresses uniform nano-particles and large meso-pore diameters of 26 nm. H2-TPR and XRD indicate that PdO is well dispersed on the supports and strongly interacted with each other. The results of XPS show that the electron density around PdO and the proportion of active oxygen on TiO2-Zro.sAl0.501.75 are maxima among the five supports.
基金supported by the National Natural Science Foundation of China(21173153)the Project from Sichuan Provincial Environment Office of China(2011HB002)the National High Technology Research and Development Program of China(2013AA065304)
文摘A series of CexZr1-xO2(0 B x B 1)with different molar ratios of Ce/Zr were syhthesized via coprecipitation method,and Fe2O3-WO3/CexZr1-xO2monolithic catalysts were prepared for selective catalytic reduction of nitrogen oxides by ammonia(NH3-SCR).The structural properties and redox behavior of the catalysts were comprehensively characterized by N2physisorption,X-ray diffraction(XRD),X-ray photoelectron spectra(XPS),H2-temperature programmed reduction(H2-TPR)and activity measurement for NH3-SCR.The results showed that the NH3-SCR activities of the catalysts were gradually enhanced by increasing the molar ratios of Ce/Zr,especially the lowtemperature catalytic activity and the reaction temperature window.Fe2O3-WO3/Ce0.68Zr0.32O2monolithic catalyst presented the best NH3-SCR activity among the investigated catalysts,more than 90%NOxcould be removed in the temperature range of 247–454°C on the catalyst under the gas hourly space velocities of 30,000 h-1.And it always held more than 99%N2selectivity and less than 20 ppm(1 ppm=10-6L/L)N2O generation concentration between 200 and500°C,the catalyst also displayed its strong resistance of H2O and SO2.Good textural and structural properties,more surface Fe,Ce and active oxygen were together contributed to the excellent NH3-SCR performance of Fe2O3-WO3/Ce0.68Zr0.32O2catalyst.
