A simple and green technique has been developed to prepare hierarchical biomorphic ZrO2- CeO2, using silkworm silk as the template. Different from traditional immersion technics, the whole synthesis process depends mo...A simple and green technique has been developed to prepare hierarchical biomorphic ZrO2- CeO2, using silkworm silk as the template. Different from traditional immersion technics, the whole synthesis process depends more on the restriction or direction functions of the silkworm silk template. The analytic results showed that ZrO2-CeO2 exhibited a well-crystallized hierarchically interwoven hollow fiber structure with 16-28 μm in diameter. The grain size of the sample calcined at 800 ℃ was about 14 nm. Consequently, the interwoven meshwork at three dimensions is formed due to the direction of biotemplate. The action mechanism is summarily discussed here. It may bring the biomorphic ZrO2-CeO2 nanomaterials with hierarchical interwoven structures to more applications, such as catalysts.展开更多
A supported amorphous Ru-Co/ZrO 2 catalyst was prepared by using formaldehyde as reduetant. The amorphous character of the catalyst was estimated by XRD, TG-DTA and SEM. The amorphous Ru-Co/ZrO 2 catalyst has higher s...A supported amorphous Ru-Co/ZrO 2 catalyst was prepared by using formaldehyde as reduetant. The amorphous character of the catalyst was estimated by XRD, TG-DTA and SEM. The amorphous Ru-Co/ZrO 2 catalyst has higher selectivity than Ru/ZrO 2 in the selective hydrogenation of benzene to cyclohexene when the experiments were run in simulated production conditions. Presence of Co in the catalyst favored the selectivity of Ru-Co/ZrO 2 but decreased its activity.展开更多
The mechanism of CO 2 methanation over Ru/ZrO 2 catalyst has been studied by means of diffuse reflectance infrared Fourier-transform spectroscopy. The results indicate that the formation of carbon-containing species o...The mechanism of CO 2 methanation over Ru/ZrO 2 catalyst has been studied by means of diffuse reflectance infrared Fourier-transform spectroscopy. The results indicate that the formation of carbon-containing species on the surface of catalyst is involved in the catalytic process. The adsorbed carbonate, formate and carbon monoxide can be detected on the surface of Ru/ZrO 2 catalyst. The surface carbonate and formate are much more abundant than the surface carbon monoxide. The surface carbonate and formate are main intermediates for the catalytic methanation of CO 2 over Ru/ZrO 2 catalyst, which can be directly hydrogenated to methane in the presence of hydrogen.展开更多
A novel solid superacid catalyst S2O8^2-/ZrO2-CeO2 was prepared by a coprecipitation method and characterized by means of XRD FTIR, BET, TEM and DSC/TG analysis methods. The results indicated that incorporation of app...A novel solid superacid catalyst S2O8^2-/ZrO2-CeO2 was prepared by a coprecipitation method and characterized by means of XRD FTIR, BET, TEM and DSC/TG analysis methods. The results indicated that incorporation of appropriate amounts of Ce into the catalyst was beneficial to the formation of sole tetragonal ZrO2 and effectively prevented from the formation of monoclinic ZrO〉 and restrained the loss of sulfated species. XRD revealed the presence of tetragonal Ce0.16Zr0.84O2phase in the case of S2O8^2-/ZrO2-CeO2 calcined above 500 ℃. Catalytic activities of S2O8^2-/ZrO2-CeO2 for the esterification of lactic acid with n-butanol was studied. The results showed that the optimum conditions were as follows： calcination temperature of the catalyst 600 ℃, n（lactic acid）：n（n-butyl alcohol）=1.0：3.0, w（S2O8^2-/ZrO2- CeO2）=12.0%, reaction temperature 145 ℃, and reaction time 2 h. The esterification efficiency of lactic acid was about 96.6%.展开更多
Ni catalysts supported on Al2O3, ZrO2-Al2O3, CeO2-Al2O3 and ZrO2-CeO2-Al2O3 were prepared by coprecipitation method, and their catalytic performances for autothermal reforming of methane to hydrogen were investigated....Ni catalysts supported on Al2O3, ZrO2-Al2O3, CeO2-Al2O3 and ZrO2-CeO2-Al2O3 were prepared by coprecipitation method, and their catalytic performances for autothermal reforming of methane to hydrogen were investigated. The Ni-supported catalysts were characterized by XRD, TPR and XPS. The relationship between the structures and catalytic activities of the catalysts was discussed. The results showed that the catalytic activity and stability of the Ni/ZrO2-CeO2-Al2O3 catalyst was better than those of other catalysts with the highest CH4 conversion, H2/CO and H2/COx ratio at 750 ℃. The catalyst showed a little deactivation along the reaction time during its 72 h on stream with the mean deactivation rate of 0.08%/h. The catalytic performance of the Ni/ZrO2-CeO2-Al2O3 catalyst was also affected by reaction temperature, no2 ： nCH4 molar ratio and nH2O ： nCH4 molar ratio. TPR, XRD and XPS measurements indicated that the formation of ZrO2-CeO2 solid solution could improve the dispersion of NiO, and inhibit the formation of NiAl2O3, and thus significantly promoted the catalytic activity of the Ni/ZrO2-CeO2-Al2O3 catalyst.展开更多
An optimal set of thermodynamic parameters of the ZrO2-CeO1.5 system has been obtained using phase diagram data by modern CALPHAD (CALculation of PHAse Diagrams) technique. The liquid and other solid solution phases w...An optimal set of thermodynamic parameters of the ZrO2-CeO1.5 system has been obtained using phase diagram data by modern CALPHAD (CALculation of PHAse Diagrams) technique. The liquid and other solid solution phases were regarded as substitutional solution. The ordered Zr2Ce2O7 phase was treated as a stoichiometric compound. The ZrO2-CeO2 system has been re-optimized with new reference state. A comparison between the ZrO2-CeO2 system and ZrO2-CeO1.5 system has been made through calculation. With the calculation, the experimental information is well reproduced and a good agreement is obtained.展开更多
文摘A simple and green technique has been developed to prepare hierarchical biomorphic ZrO2- CeO2, using silkworm silk as the template. Different from traditional immersion technics, the whole synthesis process depends more on the restriction or direction functions of the silkworm silk template. The analytic results showed that ZrO2-CeO2 exhibited a well-crystallized hierarchically interwoven hollow fiber structure with 16-28 μm in diameter. The grain size of the sample calcined at 800 ℃ was about 14 nm. Consequently, the interwoven meshwork at three dimensions is formed due to the direction of biotemplate. The action mechanism is summarily discussed here. It may bring the biomorphic ZrO2-CeO2 nanomaterials with hierarchical interwoven structures to more applications, such as catalysts.
文摘A supported amorphous Ru-Co/ZrO 2 catalyst was prepared by using formaldehyde as reduetant. The amorphous character of the catalyst was estimated by XRD, TG-DTA and SEM. The amorphous Ru-Co/ZrO 2 catalyst has higher selectivity than Ru/ZrO 2 in the selective hydrogenation of benzene to cyclohexene when the experiments were run in simulated production conditions. Presence of Co in the catalyst favored the selectivity of Ru-Co/ZrO 2 but decreased its activity.
文摘The mechanism of CO 2 methanation over Ru/ZrO 2 catalyst has been studied by means of diffuse reflectance infrared Fourier-transform spectroscopy. The results indicate that the formation of carbon-containing species on the surface of catalyst is involved in the catalytic process. The adsorbed carbonate, formate and carbon monoxide can be detected on the surface of Ru/ZrO 2 catalyst. The surface carbonate and formate are much more abundant than the surface carbon monoxide. The surface carbonate and formate are main intermediates for the catalytic methanation of CO 2 over Ru/ZrO 2 catalyst, which can be directly hydrogenated to methane in the presence of hydrogen.
基金supported by the Science and Technique Foundation of Shaaxi Province of China (2008K07-32)the Foundation of Shaanxi Educa- tional Committee of China (08JK228)the Graduate Innovation Fund of Shaanxi University of Science and Technology
文摘A novel solid superacid catalyst S2O8^2-/ZrO2-CeO2 was prepared by a coprecipitation method and characterized by means of XRD FTIR, BET, TEM and DSC/TG analysis methods. The results indicated that incorporation of appropriate amounts of Ce into the catalyst was beneficial to the formation of sole tetragonal ZrO2 and effectively prevented from the formation of monoclinic ZrO〉 and restrained the loss of sulfated species. XRD revealed the presence of tetragonal Ce0.16Zr0.84O2phase in the case of S2O8^2-/ZrO2-CeO2 calcined above 500 ℃. Catalytic activities of S2O8^2-/ZrO2-CeO2 for the esterification of lactic acid with n-butanol was studied. The results showed that the optimum conditions were as follows： calcination temperature of the catalyst 600 ℃, n（lactic acid）：n（n-butyl alcohol）=1.0：3.0, w（S2O8^2-/ZrO2- CeO2）=12.0%, reaction temperature 145 ℃, and reaction time 2 h. The esterification efficiency of lactic acid was about 96.6%.
基金supported by Guangdong Provincial Natural Science Foundation of China(030514)Science and Technology Plan of Guangdong Province of China(2004B33401006)Doctoral Startup Foundation of Guang Dong Pharmaceutical University.
文摘Ni catalysts supported on Al2O3, ZrO2-Al2O3, CeO2-Al2O3 and ZrO2-CeO2-Al2O3 were prepared by coprecipitation method, and their catalytic performances for autothermal reforming of methane to hydrogen were investigated. The Ni-supported catalysts were characterized by XRD, TPR and XPS. The relationship between the structures and catalytic activities of the catalysts was discussed. The results showed that the catalytic activity and stability of the Ni/ZrO2-CeO2-Al2O3 catalyst was better than those of other catalysts with the highest CH4 conversion, H2/CO and H2/COx ratio at 750 ℃. The catalyst showed a little deactivation along the reaction time during its 72 h on stream with the mean deactivation rate of 0.08%/h. The catalytic performance of the Ni/ZrO2-CeO2-Al2O3 catalyst was also affected by reaction temperature, no2 ： nCH4 molar ratio and nH2O ： nCH4 molar ratio. TPR, XRD and XPS measurements indicated that the formation of ZrO2-CeO2 solid solution could improve the dispersion of NiO, and inhibit the formation of NiAl2O3, and thus significantly promoted the catalytic activity of the Ni/ZrO2-CeO2-Al2O3 catalyst.
基金This work is financially supported by the China-Flanders bi-lateral project (1999)0209, the Science and Technology Committee of Shanghai Municipality 005207011 and the project of the State Key Laboratory of High Performance Ceramics and Superfine Mi-cros
文摘An optimal set of thermodynamic parameters of the ZrO2-CeO1.5 system has been obtained using phase diagram data by modern CALPHAD (CALculation of PHAse Diagrams) technique. The liquid and other solid solution phases were regarded as substitutional solution. The ordered Zr2Ce2O7 phase was treated as a stoichiometric compound. The ZrO2-CeO2 system has been re-optimized with new reference state. A comparison between the ZrO2-CeO2 system and ZrO2-CeO1.5 system has been made through calculation. With the calculation, the experimental information is well reproduced and a good agreement is obtained.
