Ce-modified Mn-Fe mixed-oxide catalysts were prepared by a citric acid sol-gel method and characterized by X-ray diffraction,Raman,N2 adsorption-desorption,infrared spectra H2 temperature-programmed reduction and ther...Ce-modified Mn-Fe mixed-oxide catalysts were prepared by a citric acid sol-gel method and characterized by X-ray diffraction,Raman,N2 adsorption-desorption,infrared spectra H2 temperature-programmed reduction and thermogravimetric analyses.Their catalytic properties were investigated in ozone(O3)decomposition reaction.Results show that the small amount of rare earth metal Ce added during Mn-Fe(FM) mixed-oxide synthesis greatly improves the catalytic performance in O3 decomposition.Among the prepared catalysts.the C0.04(FM)0.96 mixed-oxide catalyst exhibits the highest catalytic activity and stability.The O3 conversion over C0.04(FM)0.96 is 98% after 24 h reaction at 25℃ under dry condition,and that over FM decreases to 90% after 16 h reaction.At 0℃,the O3 conversion over C0.04(FM)0.96 is 95% after 7 h reaction under dry condition.and that over FM slows down to 70%.Under humid condition(RH 65%),the O3 conversion over C0.04(FM)0.96 is 63% after 6.5 h reaction at 25℃.while that over FM decreases to 55%.When Ce is doped into Mn-Fe mixed oxides,the small amount of Ce enters the crystal lattice of MnO2.and partial Fe is separated to form Fe2O3.This changes cause lattice distortion and increase defects and enable the as-synthesized Ce-Fe-Mn ternary mixed-oxide catalysts to acquire additional oxygen vacancies and increase their specific surface area,thereby increasing the number of reaction sites and enhancing the catalytic performance of the catalysts for O3 decomposition.展开更多
研究了合金成分、烧结气氛对Fe Mo Mn Sn Ce C系合金的力学性能与烧结温度的影响以及在烧结合金中的作用机理。结果表明 :适量的Mn、Sn、混合稀土和氨燃烧氮基保护气氛均可加速该系合金的烧结进程 ,降低其烧结温度 ,改善其力学性能 ,而...研究了合金成分、烧结气氛对Fe Mo Mn Sn Ce C系合金的力学性能与烧结温度的影响以及在烧结合金中的作用机理。结果表明 :适量的Mn、Sn、混合稀土和氨燃烧氮基保护气氛均可加速该系合金的烧结进程 ,降低其烧结温度 ,改善其力学性能 ,而且具有协同、叠加强化效果。其强化作用主要体现在稀土元素的脱氧保碳、变质夹杂物、细化晶粒 ,Mn、Sn元素的固溶强化以及氨燃烧氮基保护气氛对烧结热效率、合金表层脱碳状况、烧结活化能的改善等方面。该系合金在氨燃烧氮基保护气氛中的合适烧结温度范围为 10 2 5～ 10 75℃ ,比Fe Mo Ni C系合金的烧结温度降低了 12 0～ 180℃。展开更多
We rationally designed a high performance denitration(De-NOx) catalyst based on a micrometer-sized spherical Mn–Ce–Fe–Ti(CP-SD)catalyst for selective catalytic reduction(SCR). This was prepared by a co-precipitatio...We rationally designed a high performance denitration(De-NOx) catalyst based on a micrometer-sized spherical Mn–Ce–Fe–Ti(CP-SD)catalyst for selective catalytic reduction(SCR). This was prepared by a co-precipitation and spray drying(CP-SD) method. The catalyst was systematically characterized, and its morphological structure and surface properties were identified. Compare with conventional Mn–Ce–Fe–Ti(CP) catalysts, the Mn–Ce–Fe–Ti(CP-SD) catalyst had superior surface-adsorbed oxygen leading to enhanced 'fast NH3-SCR' reaction. The asobtained Mn–Ce–Fe–Ti(CP-SD) catalyst offered excellent NO conversion and N2 selectivity of 100.0% and 84.8% at 250℃, respectively, with a gas hourly space velocity(GHSV) of 40,000 h-1. The porous micro-spherical structure provides a larger surface area and more active sites to adsorb and activate the reaction gases. In addition, the uniform distribution and strong interaction of manganese, iron, cerium, and titanium oxide species improved H2O and SO2 resistance. The results showed that the Mn–Ce–Fe–Ti(CP-SD) catalyst could be used prospectively as a denitration(De-NOx) catalyst.展开更多
基金supported by the National Natural Science Foundation of China(21506194,21676255)the Natural Science Foundation of Zhejiang Province(Y16B070011)the Commission of Science and Technology of Zhejiang province(2017C03007,2017C33106).
文摘Ce-modified Mn-Fe mixed-oxide catalysts were prepared by a citric acid sol-gel method and characterized by X-ray diffraction,Raman,N2 adsorption-desorption,infrared spectra H2 temperature-programmed reduction and thermogravimetric analyses.Their catalytic properties were investigated in ozone(O3)decomposition reaction.Results show that the small amount of rare earth metal Ce added during Mn-Fe(FM) mixed-oxide synthesis greatly improves the catalytic performance in O3 decomposition.Among the prepared catalysts.the C0.04(FM)0.96 mixed-oxide catalyst exhibits the highest catalytic activity and stability.The O3 conversion over C0.04(FM)0.96 is 98% after 24 h reaction at 25℃ under dry condition,and that over FM decreases to 90% after 16 h reaction.At 0℃,the O3 conversion over C0.04(FM)0.96 is 95% after 7 h reaction under dry condition.and that over FM slows down to 70%.Under humid condition(RH 65%),the O3 conversion over C0.04(FM)0.96 is 63% after 6.5 h reaction at 25℃.while that over FM decreases to 55%.When Ce is doped into Mn-Fe mixed oxides,the small amount of Ce enters the crystal lattice of MnO2.and partial Fe is separated to form Fe2O3.This changes cause lattice distortion and increase defects and enable the as-synthesized Ce-Fe-Mn ternary mixed-oxide catalysts to acquire additional oxygen vacancies and increase their specific surface area,thereby increasing the number of reaction sites and enhancing the catalytic performance of the catalysts for O3 decomposition.
文摘研究了合金成分、烧结气氛对Fe Mo Mn Sn Ce C系合金的力学性能与烧结温度的影响以及在烧结合金中的作用机理。结果表明 :适量的Mn、Sn、混合稀土和氨燃烧氮基保护气氛均可加速该系合金的烧结进程 ,降低其烧结温度 ,改善其力学性能 ,而且具有协同、叠加强化效果。其强化作用主要体现在稀土元素的脱氧保碳、变质夹杂物、细化晶粒 ,Mn、Sn元素的固溶强化以及氨燃烧氮基保护气氛对烧结热效率、合金表层脱碳状况、烧结活化能的改善等方面。该系合金在氨燃烧氮基保护气氛中的合适烧结温度范围为 10 2 5～ 10 75℃ ,比Fe Mo Ni C系合金的烧结温度降低了 12 0～ 180℃。
基金supported by Major Scientific and Technological Project of Bingtuan (No.2018AA002)the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT_15R46)
文摘We rationally designed a high performance denitration(De-NOx) catalyst based on a micrometer-sized spherical Mn–Ce–Fe–Ti(CP-SD)catalyst for selective catalytic reduction(SCR). This was prepared by a co-precipitation and spray drying(CP-SD) method. The catalyst was systematically characterized, and its morphological structure and surface properties were identified. Compare with conventional Mn–Ce–Fe–Ti(CP) catalysts, the Mn–Ce–Fe–Ti(CP-SD) catalyst had superior surface-adsorbed oxygen leading to enhanced 'fast NH3-SCR' reaction. The asobtained Mn–Ce–Fe–Ti(CP-SD) catalyst offered excellent NO conversion and N2 selectivity of 100.0% and 84.8% at 250℃, respectively, with a gas hourly space velocity(GHSV) of 40,000 h-1. The porous micro-spherical structure provides a larger surface area and more active sites to adsorb and activate the reaction gases. In addition, the uniform distribution and strong interaction of manganese, iron, cerium, and titanium oxide species improved H2O and SO2 resistance. The results showed that the Mn–Ce–Fe–Ti(CP-SD) catalyst could be used prospectively as a denitration(De-NOx) catalyst.
