Mesostructured Co3O4-CeO2 composite was found to be an effective catalytic material for the complete oxidation of benzene.The Co3O4-CeO2 catalysts with different Co/Ce ratios(mol/mol)were prepared via the nanocasting ...Mesostructured Co3O4-CeO2 composite was found to be an effective catalytic material for the complete oxidation of benzene.The Co3O4-CeO2 catalysts with different Co/Ce ratios(mol/mol)were prepared via the nanocasting method and the mesostructure was replicated from two-dimensional(2D)hexagonal SBA-15 and three-dimensional(3D)cubic KIT-6 silicas,respectively.All the obtained Co3O4-CeO2 catalysts exhibited the similar symmetry with the parent silicas and well ordered mesostructures.The Co3O4-CeO2 catalysts with 2D mesostructure showed lower catalytic activities than the corresponding 3D materials.The Co3O4-CeO2 catalyst nanocasted from KIT-6 and with the Co/Ce ratio of 16/1 possessed the best catalytic benzene oxidation activity due to larger quantities of surface hydroxyl groups and surface oxygenated species.The mesostructured Co3O4-CeO2 material thus shows great potential as a promising eco-environmental catalyst for benzene effective elimination.展开更多
CeO2-based oxygen materials were prepared with co-precipitation method and characterized via Brunauer-Emmet Teller(BET)method,X-ray diffraction(XRD)and temperature-programmed reduction(H2-TPR).This paper revealed that...CeO2-based oxygen materials were prepared with co-precipitation method and characterized via Brunauer-Emmet Teller(BET)method,X-ray diffraction(XRD)and temperature-programmed reduction(H2-TPR).This paper revealed that three CeO2-based oxygen storage materials are all forming homogeneous solid solution.Among the samples,CeO2-ZrO2-Al2O3(CZA)has the best textural properties and excellent thermal stability.The specific surface area and pore volume of aged CZA are 90 m2/g and 0.29 mL/g.We proposed a viewpoint:Al3+ might insert among the interspace of fluorite structure or highly dispersal in solid solutions.展开更多
A series of Co3O4-CeO2 binary oxides with various Co/(Ce+Co)molar ratios were synthesized using a citric acid method,and their catalytic properties toward the total oxidation of propane were examined.The activities of...A series of Co3O4-CeO2 binary oxides with various Co/(Ce+Co)molar ratios were synthesized using a citric acid method,and their catalytic properties toward the total oxidation of propane were examined.The activities of the catalysts decrease in the order CoCeOx-70>CoCeOx-90>Co3O4>CoCeOx-50>CoCeOx-20>CeO2.CoCeOx-70(Co/(Ce+Co)=70% molar ratio)exhibits the highest catalytic activity toward the total oxidation of propane,of which the T90 is 310℃(GHSV=120000 mL h^-1 g^-1],which is 25℃ lower than that of pure Co3 O4.The enhancement of the catalytic performance of CoCeOx-70 is attributed to the strong interaction between CeO2 and Co3O4,the improvement of the low-temperature reducibility,and the increase in the number of active oxygen species.In-situ DRIFTS and reaction kinetics measurement reveal that Ce addition does not change the reaction mechanism,but promotes the adsorption and activation of propane on the catalyst surface.The addition of water vapor and CO2 in reactant gas has a negative effect on the propane conversion,and the catalyst is more sensitive to water vapor than to CO2.In addition,CoCeOx-70 exhibits excellent stability and reusability in water vapor and CO2 atmosphere.展开更多
Ce-Zr-Al-Nd2O3 (CZAN) support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction (XRD), low temperature nitrogen adsorption-desorption,...Ce-Zr-Al-Nd2O3 (CZAN) support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction (XRD), low temperature nitrogen adsorption-desorption, oxygen pulsing technique, H2-temperamre programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The Pd-only three-way catalysts (Pd-TWC) supported on these materials were prepared by incipient wetness method and studied by activity tests. The results demonstrated that the CZAN supports obtained by the two methods showed better structural, textural and redox properties than the CZA without Nd2O3, and the addition of Nd203 improved the catalytic activity of TWC. Especially, the CZAN-i support prepared by impregnation method had better thermal stability and redox property. Meanwhile, the Pd/CZAN-i catalyst exhibited the best catalytic performance. XPS measurements indicated that the Nd-modified samples possessed more Ce3+ and oxygen vacancies on the surface of samples, which led to a better redox property. The excellent redox property of support materials helped to improve the catalytic activity of TWC.展开更多
Mg-Li-Gd alloys were prepared by electrochemical codeposition from LiCl-KCl-MgCl 2 -Gd 2 O 3 melts on molybdenum electrode with constant current density at 823 and 973 K. The microstructure of the Mg-Li-Gd alloys was ...Mg-Li-Gd alloys were prepared by electrochemical codeposition from LiCl-KCl-MgCl 2 -Gd 2 O 3 melts on molybdenum electrode with constant current density at 823 and 973 K. The microstructure of the Mg-Li-Gd alloys was analyzed by X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM). The results show that magnesium and gadolinium deposit mainly in the first 30 min, and the alloy obtained contains 96.53% Mg, 0.27% Li and 3.20% Gd (mass fraction). Then, the reduction of lithium ions occurs quickly. The composition of alloy can be adjusted by controlling electrolysis time or Gd 2 O 3 concentration in LiCl-KCl melts. With the addition of Gd into Mg-Li alloys, the corrosion resistance of the alloys is enhanced. XRD results suggest that Mg 3 Gd and Mg 2 Gd can be formed in Mg-Li-Gd alloys. The distribution of Gd element in Mg-Li-Gd alloys indicates that Gd element mainly distributes at the grain boundaries of Mg-Li-Gd alloys.展开更多
Cubic and monoclinic Gd2O3:Eu3+ phosphors in the range of nano-scale and submicron-scale were prepared by a modified solution combustion method.Coexistence of cubic and monoclinic phases was found in the highest lumin...Cubic and monoclinic Gd2O3:Eu3+ phosphors in the range of nano-scale and submicron-scale were prepared by a modified solution combustion method.Coexistence of cubic and monoclinic phases was found in the highest luminescent sample synthesized at 600 oC.In relation to commercial sample,the relative luminescence intensity was 49.8%.The shape of emission spectrum of the sample thus changed and the charge-transfer-state band of excitation spectrum slightly shift toward higher energies.With increasing the anneal...展开更多
基金supported by the National Natural Science Funds for Distinguished Young Scholar(No.20725723)the National Basic Research Program of China(No.2010CB732300)the National High Technology Research and Development Program of China(No.2006AA06A310)
摘要Mesostructured Co3O4-CeO2 composite was found to be an effective catalytic material for the complete oxidation of benzene.The Co3O4-CeO2 catalysts with different Co/Ce ratios(mol/mol)were prepared via the nanocasting method and the mesostructure was replicated from two-dimensional(2D)hexagonal SBA-15 and three-dimensional(3D)cubic KIT-6 silicas,respectively.All the obtained Co3O4-CeO2 catalysts exhibited the similar symmetry with the parent silicas and well ordered mesostructures.The Co3O4-CeO2 catalysts with 2D mesostructure showed lower catalytic activities than the corresponding 3D materials.The Co3O4-CeO2 catalyst nanocasted from KIT-6 and with the Co/Ce ratio of 16/1 possessed the best catalytic benzene oxidation activity due to larger quantities of surface hydroxyl groups and surface oxygenated species.The mesostructured Co3O4-CeO2 material thus shows great potential as a promising eco-environmental catalyst for benzene effective elimination.
摘要CeO2-based oxygen materials were prepared with co-precipitation method and characterized via Brunauer-Emmet Teller(BET)method,X-ray diffraction(XRD)and temperature-programmed reduction(H2-TPR).This paper revealed that three CeO2-based oxygen storage materials are all forming homogeneous solid solution.Among the samples,CeO2-ZrO2-Al2O3(CZA)has the best textural properties and excellent thermal stability.The specific surface area and pore volume of aged CZA are 90 m2/g and 0.29 mL/g.We proposed a viewpoint:Al3+ might insert among the interspace of fluorite structure or highly dispersal in solid solutions.
基金supported by the National Key R&D Program of China(2016YFB0600305)~~
摘要A series of Co3O4-CeO2 binary oxides with various Co/(Ce+Co)molar ratios were synthesized using a citric acid method,and their catalytic properties toward the total oxidation of propane were examined.The activities of the catalysts decrease in the order CoCeOx-70>CoCeOx-90>Co3O4>CoCeOx-50>CoCeOx-20>CeO2.CoCeOx-70(Co/(Ce+Co)=70% molar ratio)exhibits the highest catalytic activity toward the total oxidation of propane,of which the T90 is 310℃(GHSV=120000 mL h^-1 g^-1],which is 25℃ lower than that of pure Co3 O4.The enhancement of the catalytic performance of CoCeOx-70 is attributed to the strong interaction between CeO2 and Co3O4,the improvement of the low-temperature reducibility,and the increase in the number of active oxygen species.In-situ DRIFTS and reaction kinetics measurement reveal that Ce addition does not change the reaction mechanism,but promotes the adsorption and activation of propane on the catalyst surface.The addition of water vapor and CO2 in reactant gas has a negative effect on the propane conversion,and the catalyst is more sensitive to water vapor than to CO2.In addition,CoCeOx-70 exhibits excellent stability and reusability in water vapor and CO2 atmosphere.
基金Project supported by National Natural Science Foundation of China (20773090, 20803049)the Specialized Research Fund for the Doctoral Program of Higher Education (20070610026, 200806100009)
摘要Ce-Zr-Al-Nd2O3 (CZAN) support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction (XRD), low temperature nitrogen adsorption-desorption, oxygen pulsing technique, H2-temperamre programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The Pd-only three-way catalysts (Pd-TWC) supported on these materials were prepared by incipient wetness method and studied by activity tests. The results demonstrated that the CZAN supports obtained by the two methods showed better structural, textural and redox properties than the CZA without Nd2O3, and the addition of Nd203 improved the catalytic activity of TWC. Especially, the CZAN-i support prepared by impregnation method had better thermal stability and redox property. Meanwhile, the Pd/CZAN-i catalyst exhibited the best catalytic performance. XPS measurements indicated that the Nd-modified samples possessed more Ce3+ and oxygen vacancies on the surface of samples, which led to a better redox property. The excellent redox property of support materials helped to improve the catalytic activity of TWC.
基金Project(2009AA050702)supported by the National High-tech Research and Development Program of ChinaProject(GC06A212)supported by the Scientific Technology Project of Heilongjiang Province,China+2 种基金Project(50871033)supported by the National Natural Science Foundation of ChinaProject(208181)supported by the Key Project of Ministry of Education,ChinaProject(HEUCF101002)supported by the Fundamental Research Funds for the Central Universities,China
摘要Mg-Li-Gd alloys were prepared by electrochemical codeposition from LiCl-KCl-MgCl 2 -Gd 2 O 3 melts on molybdenum electrode with constant current density at 823 and 973 K. The microstructure of the Mg-Li-Gd alloys was analyzed by X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM). The results show that magnesium and gadolinium deposit mainly in the first 30 min, and the alloy obtained contains 96.53% Mg, 0.27% Li and 3.20% Gd (mass fraction). Then, the reduction of lithium ions occurs quickly. The composition of alloy can be adjusted by controlling electrolysis time or Gd 2 O 3 concentration in LiCl-KCl melts. With the addition of Gd into Mg-Li alloys, the corrosion resistance of the alloys is enhanced. XRD results suggest that Mg 3 Gd and Mg 2 Gd can be formed in Mg-Li-Gd alloys. The distribution of Gd element in Mg-Li-Gd alloys indicates that Gd element mainly distributes at the grain boundaries of Mg-Li-Gd alloys.
基金supported by the Ministry of Science and Technology of China (2006CB601104)the Foundation of International Joint Research of Beijing (2007N08)+1 种基金Natural Science Foundation of Jiangxi Province (2009GQC0042)Foundation of Jiangxi Educational Committee (GJJ10153)
摘要Cubic and monoclinic Gd2O3:Eu3+ phosphors in the range of nano-scale and submicron-scale were prepared by a modified solution combustion method.Coexistence of cubic and monoclinic phases was found in the highest luminescent sample synthesized at 600 oC.In relation to commercial sample,the relative luminescence intensity was 49.8%.The shape of emission spectrum of the sample thus changed and the charge-transfer-state band of excitation spectrum slightly shift toward higher energies.With increasing the anneal...