A series of catalysts were prepared by doping different loadings of CeO2 over TiO2-SiO2-WO3 and used for the selective catalytic reduction of NOx by NH3. The experimental results showed that the selective catalytic re...A series of catalysts were prepared by doping different loadings of CeO2 over TiO2-SiO2-WO3 and used for the selective catalytic reduction of NOx by NH3. The experimental results showed that the selective catalytic reduction(SCR) performance and SO2-resistant ability of TiO2-SiO2-WO3 were greatly enhanced by the introduction of cerium. The catalyst containing 10% CeO2 showed the highest NO conversion in a wide temperature range and good N2 selectivity with broad operation temperature window at the gas hourly space velocity(GHSV) of 30000 h–1, which was a very promising catalyst for NOx abatement from diesel engine exhaust. The catalysts were characterized by X-ray diffraction(XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy(SEM-EDS), N2 adsorption-desorption(BET) and X-ray photoelectron spectroscopy(XPS). The characterization results showed that the bigger pore radius, higher surface atomic concentration and dispersion of Ce and the abundant adsorbed oxygen on the surface of catalyst contributed to the best NH3-SCR performance of CeO2/TiO2-SiO2-WO3 catalyst containing 10% CeO2.展开更多
A series of Ce-promoted Mn-Na2WO4/SiO2 catalysts were prepared by incipient wetness impregnation method, and their catalytic performance for oxidative coupling of methane (OCM) was investigated at atmospheric pressu...A series of Ce-promoted Mn-Na2WO4/SiO2 catalysts were prepared by incipient wetness impregnation method, and their catalytic performance for oxidative coupling of methane (OCM) was investigated at atmospheric pressure in a micro-quartz-tube reactor. The catalysts were characterized by X-ray diffraction (XRD), temperature program reduction (TPR) and BET surface area. Ce promoter increased surface area and Na2WO4 species dispersion, which enriched the amount of the surface species. In addition, Ce promoter increased the Na/W species reduction, but the reduction peak shifted to higher temperature. Stability test of 5wt%Ce catalyst indicated suitable performance and stability. The selectivity and yield of C^2+ hydrocarbons after 50 h operation reached 65.5% and 19.6%, respectively, at 840 ℃ over 5wt%Ce-2wt%Mn5wt%Na2WO4/SiO2 catalyst.展开更多
XRD, Raman, TEM, and N2-adsorption were utilized to characterize CeO2/SiO2 prepared by coprecipi-tation and surfactant-assisted method. The results show that nanocrystalline CeO2 can be uniformly supported on the surf...XRD, Raman, TEM, and N2-adsorption were utilized to characterize CeO2/SiO2 prepared by coprecipi-tation and surfactant-assisted method. The results show that nanocrystalline CeO2 can be uniformly supported on the surface of SiO2 particles, when the molar ratio of Si4+/(Ce3++Si4+) is less than 35% in coprecipitation samples. At higher Si content, the surface of SiO2 can not be fully covered by CeO2. With surfactant (CTAB) added, the u-iformly supported structure can even exist when the molar ratio of Si4+/(Ce3++Si4+) is as high as 53%. It is because Ce and Si complexes can be well dispersed in precursor solution in present of CTAB. However, the uniformly supported structure can not be synthesised through surfactant-assisted approch for its hydrothermal threatment, which can easily lead to separate aggregation of nanocrystalline CeO2 and SiO2 particles.展开更多
本文采用铈掺杂的CuO-SiO_2复合氧化物作为催化剂,双氧水为氧化剂,以氧化脱除模拟油中苯并噻吩反应为探针,通过单因素实验考察氧化剂用量、溶剂用量、催化剂用量、氧化温度和氧化时间等因素对脱硫效果的影响。研究结果表明,铈掺杂的0.02...本文采用铈掺杂的CuO-SiO_2复合氧化物作为催化剂,双氧水为氧化剂,以氧化脱除模拟油中苯并噻吩反应为探针,通过单因素实验考察氧化剂用量、溶剂用量、催化剂用量、氧化温度和氧化时间等因素对脱硫效果的影响。研究结果表明,铈掺杂的0.02CeO_2-0.1CuO-SiO_2复合氧化物比表面积比未掺杂的比表面积略高,在模拟油用量10 m L、复合氧化物催化剂用量0.10 g、溶剂乙腈用量2.0 m L,氧化剂30%H_2O_20.2 m L、氧化反应温度65℃的条件下反应60 min,脱硫率为88.23%。展开更多
基金supported by the National Natural Science Foundation of China(21173153)the National High Technology Research and Development Program of China(863 project)(2013AA065304)
摘要A series of catalysts were prepared by doping different loadings of CeO2 over TiO2-SiO2-WO3 and used for the selective catalytic reduction of NOx by NH3. The experimental results showed that the selective catalytic reduction(SCR) performance and SO2-resistant ability of TiO2-SiO2-WO3 were greatly enhanced by the introduction of cerium. The catalyst containing 10% CeO2 showed the highest NO conversion in a wide temperature range and good N2 selectivity with broad operation temperature window at the gas hourly space velocity(GHSV) of 30000 h–1, which was a very promising catalyst for NOx abatement from diesel engine exhaust. The catalysts were characterized by X-ray diffraction(XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy(SEM-EDS), N2 adsorption-desorption(BET) and X-ray photoelectron spectroscopy(XPS). The characterization results showed that the bigger pore radius, higher surface atomic concentration and dispersion of Ce and the abundant adsorbed oxygen on the surface of catalyst contributed to the best NH3-SCR performance of CeO2/TiO2-SiO2-WO3 catalyst containing 10% CeO2.
摘要A series of Ce-promoted Mn-Na2WO4/SiO2 catalysts were prepared by incipient wetness impregnation method, and their catalytic performance for oxidative coupling of methane (OCM) was investigated at atmospheric pressure in a micro-quartz-tube reactor. The catalysts were characterized by X-ray diffraction (XRD), temperature program reduction (TPR) and BET surface area. Ce promoter increased surface area and Na2WO4 species dispersion, which enriched the amount of the surface species. In addition, Ce promoter increased the Na/W species reduction, but the reduction peak shifted to higher temperature. Stability test of 5wt%Ce catalyst indicated suitable performance and stability. The selectivity and yield of C^2+ hydrocarbons after 50 h operation reached 65.5% and 19.6%, respectively, at 840 ℃ over 5wt%Ce-2wt%Mn5wt%Na2WO4/SiO2 catalyst.
摘要XRD, Raman, TEM, and N2-adsorption were utilized to characterize CeO2/SiO2 prepared by coprecipi-tation and surfactant-assisted method. The results show that nanocrystalline CeO2 can be uniformly supported on the surface of SiO2 particles, when the molar ratio of Si4+/(Ce3++Si4+) is less than 35% in coprecipitation samples. At higher Si content, the surface of SiO2 can not be fully covered by CeO2. With surfactant (CTAB) added, the u-iformly supported structure can even exist when the molar ratio of Si4+/(Ce3++Si4+) is as high as 53%. It is because Ce and Si complexes can be well dispersed in precursor solution in present of CTAB. However, the uniformly supported structure can not be synthesised through surfactant-assisted approch for its hydrothermal threatment, which can easily lead to separate aggregation of nanocrystalline CeO2 and SiO2 particles.
摘要本文采用铈掺杂的CuO-SiO_2复合氧化物作为催化剂,双氧水为氧化剂,以氧化脱除模拟油中苯并噻吩反应为探针,通过单因素实验考察氧化剂用量、溶剂用量、催化剂用量、氧化温度和氧化时间等因素对脱硫效果的影响。研究结果表明,铈掺杂的0.02CeO_2-0.1CuO-SiO_2复合氧化物比表面积比未掺杂的比表面积略高,在模拟油用量10 m L、复合氧化物催化剂用量0.10 g、溶剂乙腈用量2.0 m L,氧化剂30%H_2O_20.2 m L、氧化反应温度65℃的条件下反应60 min,脱硫率为88.23%。