Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2+OH and C6+OH in alcohol distribution was very high while the methane product...Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2+OH and C6+OH in alcohol distribution was very high while the methane product fraction in hydrocarbon distribution was rather low, demonstrating a promising potential in higher alcohols synthesis from syngas. The distribution of alcohols and hydrocarbons approximately obeyed Anderson-Schulz-Flory distribution with similar chain growth probability, indicating alcohols and hydrocarbons derived from the same intermediates. The effects of Cu/Fe molar ratio, reaction temperature and gas hourly space velocity (GHSV) on catalytic performance were studied in detail. The sample with a Cu/Fe molar ratio of 10/1 exhibited the best catalytic performance. Higher reaction temperature accelerated water-gas-shift reaction and led to lower total alcohols selectivity. GHSV showed great effect on catalytic performance and higher GHSV increased the total alcohol selectivity, indicating there existed visible dehydration reaction of alcohol into hydrocarbon.展开更多
Iron-manganese composited oxide(FeMnO) was prepared with potassium permanganate and ferrous salt. Interface performance, charge property and structure topography of the FeMnO were investigated. Coagulation efficienc...Iron-manganese composited oxide(FeMnO) was prepared with potassium permanganate and ferrous salt. Interface performance, charge property and structure topography of the FeMnO were investigated. Coagulation efficiency and pollution removal mechanism of the FeMnO were approached. Results show that the main compositions of the FeMnO are δ-manganese dioxide and ferric hydroxide. The specific surface area is about 146.22 m^2/g. The FeMnO contains rich hydroxyl with extremely strong adsorption action and chemical adsorption activity. The zero charge point of the oxide in pure water is about 8.0 of pH value. Under neutral pH value conditions, the FeMnO particle surface carried positive charges. The FeMnO particles are quasi-spherical micro-particles with irregular sizes adjoined each other to form net construction. Phosphorus removal efficiency of the FeMnO is remarkable, the total dissoluble phosphorus of settled water can be reduced below detecting level(0.3 μtg/L) at a FeMnO dosage of 6 mg/L, and total phosphorus below detecting level at a FeMnO dosage of 10 mg/L, for water samples containing total phos- phorus of 1281.70 μg/L and total dissoluble phosphorus of 1187.91 μtg/L. The mechanism of effective coagulation for phosphorus removal is combined results of multiple actions of adsorption, charge neutralization, adsorption/bridging and so on.展开更多
A coating of composition Si-40Mo (wt pct) was prepared by fused slurry coating method on the two-dimensional carbon/carbon (2D-C/C) composite to improve oxidation resistance. In the procedure of the fabrication, pure ...A coating of composition Si-40Mo (wt pct) was prepared by fused slurry coating method on the two-dimensional carbon/carbon (2D-C/C) composite to improve oxidation resistance. In the procedure of the fabrication, pure St slurry inner layer in the pre-coating was necessary to apply because of infiltration of liquid Si into the substrate during the sintering. The coating consists of Si continuous phase and MoSi2 particles. In addition, the infiltration of Si into the substrate and the SiC reaction layer between the coating and the C/C composite were observed. Oxidation behavior of coated and uncoated C/C composites was studied in cyclic mode. The oxidation resistance and the thermal shock resistance of the Si-Mo fused slurry coating were quite excellent at 1370℃.展开更多
A series of novel Ni/CeOe-Al2O3 composite catalysts were synthesized by one-step citric acid complex method, The as-synthesized catalysts were characterized by N2 physical adsorption/desorption, X-ray diffraction (XR...A series of novel Ni/CeOe-Al2O3 composite catalysts were synthesized by one-step citric acid complex method, The as-synthesized catalysts were characterized by N2 physical adsorption/desorption, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, hydrogen temperature-programmed reduction (Hz-TPR), X-ray photoelectron spectroscopy (XPS) and thermogravimetry analysis (TGA). The effects of nickel content, calcination and reaction temperatures, gas hourly space velocity (GHSV) and inert gas dilution of N2 on their performance of catalytic partial oxidation of methane (CPOM) were investigated. Catalytic activity test results show that the highest methane conversion (〉85%), the best selectivities to carbon monoxide (〉87%) and to hydrogen (〉95%), the excellent stability and perfect Hz/CO ratio (2.0) can be obtained over Ni/CeO2-Al2O3 with 8 wt% Ni content calcined at 700 ℃ under the reaction condition of 750 ℃, CH4/O2 ratio of 2 : 1 and gas hourly space velocity of 12000 mL.h-1 .g-1. Characterization results show that the good catalytic performance of this composite catalyst can be contributed to its large specific surface area (~108 m2.g-1), small crystallite size, easy reducibility and low coking rate.展开更多
CO2-TPD was demonstrated an effective way to investigate the phase formation during pyrolysis for the preparation of composite oxides using metal-organic molecules as precursors.Based on the CO2-TPD results, it was f...CO2-TPD was demonstrated an effective way to investigate the phase formation during pyrolysis for the preparation of composite oxides using metal-organic molecules as precursors.Based on the CO2-TPD results, it was found that calcination condition had deep effect on the carbonate formation and the minimum firing temperature to acquire pure phase composite oxide.An optimized calcination schedule was then developed.展开更多
A mesoporous Al-Mg composite oxide with a hexagonal structure was synthesized with aluminium nitrate and magnesium nitrate as the reagents and sodium dodecyl sulfate(SDS) as the template in the presence of ethylened...A mesoporous Al-Mg composite oxide with a hexagonal structure was synthesized with aluminium nitrate and magnesium nitrate as the reagents and sodium dodecyl sulfate(SDS) as the template in the presence of ethylenediamine. The XRD, nitrogen adsorption-desorption and TEM studies indicate that the composite has a hexagonal framework structure and an average pore diameter of 2. 6 nm. The TG/DTA spectra indicate that the decomposition and the removal of the occluded surfactant of the sample take place in a range of 230-550 ℃. The mesoporous Al-Mg composite oxide exhibites a highly catalytic activity for the oxyethylation of fatty alcohols. Narrow-range distributed ethoxylates are formed in the presence of the mesoporous Al-Mg composite oxide catalyst. The distribution selectivity coefficient(Cx) is 24 when the mesoporous Al-Mg composite oxide was used as a catalyst for the oxyethylation of octanol and the average adduct degree of ethoxylates is 6. 4.展开更多
Oxidation behavior of C/C-SiC gradient matrix composites and C/C composites were compared in stationary air. The results show that oxidation threshold of C-SiC materials increases with the amount of SiC particles in t...Oxidation behavior of C/C-SiC gradient matrix composites and C/C composites were compared in stationary air. The results show that oxidation threshold of C-SiC materials increases with the amount of SiC particles in the codeposition matrix. Oxidation rate of C/C-SiC gradient matrix composites is significantly lower than that of C/C material. The micro-oxidation process was observed by SEM.展开更多
Fe3O4@SiO2 core–shell composite nanoparticles were successfully prepared by a one-pot process. Tetraethyl-orthosilicate was used as a surfactant to synthesize Fe3O4@SiO2 core–shell structures from prepared Fe3O4 nan...Fe3O4@SiO2 core–shell composite nanoparticles were successfully prepared by a one-pot process. Tetraethyl-orthosilicate was used as a surfactant to synthesize Fe3O4@SiO2 core–shell structures from prepared Fe3O4 nanoparticles. The properties of the Fe3O4 and Fe3O4@SiO2 composite nanoparticles were studied by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The prepared Fe3O4 particles were approximately 12 nm in size, and the thickness of the SiO2 coating was approximately 4 nm. The magnetic properties were studied by vibrating sample magnetometry. The results show that the maximum saturation magnetization of the Fe3O4@SiO2 powder(34.85 A·m^2·kg^–1) was markedly lower than that of the Fe3O4 powder(79.55 A·m^2·kg^–1), which demonstrates that Fe3O4 was successfully wrapped by SiO2. The Fe3O4@SiO2 composite nanoparticles have broad prospects in biomedical applications; thus, our next study will apply them in magnetic resonance imaging.展开更多
The electrical and optical properties of the indium tin oxide (ITO)/epoxy composite exhibit dramatic variations as functions of the ITO composition and ITO particle size. Sharp increases in the conductivity in the v...The electrical and optical properties of the indium tin oxide (ITO)/epoxy composite exhibit dramatic variations as functions of the ITO composition and ITO particle size. Sharp increases in the conductivity in the vicinity of a critical volume fraction have been found within the framework of percolation theory. A conductive and insulating transition model is extracted by the ITO particle network in the SEM image, and verified by the resistivity dependence on the temperature. The dependence of the optical transmittance on the particle size was studied. Further decreasing the ITO particle size could further improve the percolation threshold and light transparency of the composite film.展开更多
The fracture toughness of a carbon/carbon composites oxidized at different temperature for 1 h was measured. The fracture surfaces were examined by scanning electron microscopy (SEM). The results indicate that oxida...The fracture toughness of a carbon/carbon composites oxidized at different temperature for 1 h was measured. The fracture surfaces were examined by scanning electron microscopy (SEM). The results indicate that oxidation temperature has significant effects on the fracture toughness. Fracture toughness decreases with the increase of the weight loss. The SEM images reveal that the decrease of fracture toughness was mainly attributed to the oxidation of the interface in the composite.展开更多
A series of composites as electrode materials for supercapacitors were prepared via incipient wetness impregnation method utilizing ordered mesoporous carbon (OMC) and tin (IV) oxide (SnO2) with different ratio....A series of composites as electrode materials for supercapacitors were prepared via incipient wetness impregnation method utilizing ordered mesoporous carbon (OMC) and tin (IV) oxide (SnO2) with different ratio.The structure and electrochemical properties of the OMC/SnO2 composites were characterized by XRD,TEM and cyclic voltammetry (CV).Pore characteristics were measured by nitrogen adsorption and desorption isotherms.The results show that the structure and electrochemical properties of the composites depend mainly on the loading amount of SnO2 in the ordered mesoporous carbon.The optimum amount of SnCl4 added is found to be 40 % (1.54 g ethanol-based SnCl4·5H2O added to 1 g OMC) of the saturated solution.The specific capacitance of the composite of optimum amount of SnCl4 (200 F g-1) is nearly three times of that of the pristine SnO2 (72 F g-1) at the scan rate of 5 mV s-1,and its specific capacitance is almost equal to that of the ordered mesoporous carbon (126 F g-1) at the scan rate of 200 mV s-1.Meanwhile,it has better specific volumetric energy density than OMC due to its higher density.Besides,in the potential range of 0-0.9 V the composite electrode material exhibits a stable cycle life after 500 cycles.展开更多
YSZ/(Ni, Al) composite coatings with different Ni:Al mole ratios were deposited on superalloy Inconel 600 by electrophoretic deposition(EPD) technique, followed by sintering in CH_4 atmosphere at 1 100 ℃for 2 h ...YSZ/(Ni, Al) composite coatings with different Ni:Al mole ratios were deposited on superalloy Inconel 600 by electrophoretic deposition(EPD) technique, followed by sintering in CH_4 atmosphere at 1 100 ℃for 2 h and isothermally oxidation at 1000 ℃ for 50 h. After sintering at 1100 ℃ for 2 h in CH_4 atmosphere, besides ZrC and t-ZrO_2 phases, the phase constitutes of Ni:Al mole ratios with 1:3, 1:2, and 1:1 were(Zr, Al)C, AlNi_3 and Ni phases, respectively. A remarkable difference in the oxidation behaviors of YSZ/(Ni, Al) composite coatings with different Ni:Al mole ratios was observed. For YSZ(Ni:Al=1:3) coated sample, oxidation at 1000 ℃ causes decomposition of the(Zr,Al)C solid solution to metallic Al, and then most of the Al is oxidized to Al_2O_3. For the YSZ(Ni:Al=1:2) coated sample, oxidation at 1000 ℃ mainly causes decomposition of the AlNi_3 phase. For YSZ(Ni:Al=1:1) coated sample, after oxidation at 1000 ℃, most of the Ni is oxidized to Ni O phase, and tolerated 50 h of oxidation and finally cracked and spalled from the specimen. YSZ(Ni:Al=1:3) and YSZ(Ni:Al=1:2) coated samples show superior oxidation resistance than that of YSZ coating. The different oxidation resistance mechanisms of YSZ/(Ni, Al) composite coatings sintered in CH_4 atmosphere were discussed.展开更多
Pure copper plates were coated by Ni-TiC dipulse current plating method. The effects of adding different concentration(ranging from 0.5 g/L to 3.0 g/L) of attapulgite nano particles to the plating bath on the surfac...Pure copper plates were coated by Ni-TiC dipulse current plating method. The effects of adding different concentration(ranging from 0.5 g/L to 3.0 g/L) of attapulgite nano particles to the plating bath on the surface morphology, wear resistance, and oxidation resistance of Ni/TiC/Attapulgite nano-composite coatings were investigated. The experimental results show that the composite coating is flat and compact with adding 3.0 g/L in the bath, and the coating preferred orientation is changed from the planes(111) to(200). The coefficient of the composite coatings decreases from 0.68 to 0.18 with increasing content of attapulgite in the bath, a mixed mode of adhesive-abrasive wear occurs for all coatings, and the wear mechanism shows a transition from adhesive-abrasive to predominantly abrasive wear mechanism when the concentration of attapulgite is beyond 1.5 g/L in electrolyte. The oxidation resistance of composite coatings is the best prepared when adding attapulgite particles at 0.5 g/L in the bath, the oxide mainly consists of a NiO phase by X-ray analysis.展开更多
With sol-gel method, nanometer La-Ti composite oxide was successfully prepared at a low temperature (750~800C) using polyethylene glycol as dispersant. By means of atomic force microscope, the surface pattern, partic...With sol-gel method, nanometer La-Ti composite oxide was successfully prepared at a low temperature (750~800C) using polyethylene glycol as dispersant. By means of atomic force microscope, the surface pattern, particle size distribution, and specific surface area were studied. The compound particle surface appears as a smooth sheet, the mean size of the compound is 25.38 nm. On the specific surface, the particle erects at a height of 4.69 nm. The surface area is 58.90 nm2. The La-Ti composite oxide nanocrystal prefers to narrow and even particle size distribution and the homogeneity of surface topography.展开更多
Two methods for preparing La0.9K0.1CoO3 perovskite composite oxides.traditional solid state reaction method and sol-gel method.were compared.The characteristics of the powders,such as purity.particle diameter,BET surf...Two methods for preparing La0.9K0.1CoO3 perovskite composite oxides.traditional solid state reaction method and sol-gel method.were compared.The characteristics of the powders,such as purity.particle diameter,BET surface area,pore diameter,were inrestigated by using TG-DTA,XRD,SEM and BET methods.The experimental results shou that La0.9K0.1CoO3 perorskite composite oxide can be obtained by using the two methods.The purity of La0.9K0.1CoO3 powders can be increased by raising the calcining temperature while the particle diameter increased and BET surface area decreased.At the same calcining temperature,the properties of the La0.9K0.1CoO3 powders synthesized by the sol-gel method are superior to those synthesized by the solid state reaction method.such as purer phase,smaller particle diameter,which can be used as a satisfactory catalyst in diesel waste gas cleaning.展开更多
The composition,structure and micro-morphology of magnesium- iron- aluminum composite oxides were investigated using various methods such as XRF,SEM,EDS,XRD and KMn O4-titration. Compared to hercynite,the composite ox...The composition,structure and micro-morphology of magnesium- iron- aluminum composite oxides were investigated using various methods such as XRF,SEM,EDS,XRD and KMn O4-titration. Compared to hercynite,the composite oxides have completely different phases including solid solution( Mg O)0. 77( Fe O)0. 23,composite spinel Mg Fe0. 2Al1. 8O4 and a small amount of Mg Fe2O4. The composite oxides exhibit excellent corrosion resistance to cement clinker and potassium salts.The products produced by magnesite and the composite oxides show better performance than magnesia- hercynite bricks,especially the corrosion resistance and thermal shock resistance.展开更多
SiCp/Al2O3-Al composites were synthesized by means of direct metal oxidation method. The composition and microstructures of the composites were investigated using X-ray diffraction (XRD), scanning electron microsco...SiCp/Al2O3-Al composites were synthesized by means of direct metal oxidation method. The composition and microstructures of the composites were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and metallurgical microscope. The effects of technical parameters on the properties of the product were analyzed. The results indicate that the composite possesses a dense microstructure, composed of three interpenetrated phases. Of them, SiO2 layer prohibits the powdering of the composites; Mg promotes the wetting and infiltration of the system and Si restricts the interfacial reaction while improving the wetting ability between reinforcement and matrix.展开更多
Two different morphologies of ZnO(lotus-shaped, rod-shaped) and ZnO/PVDF composite materials were prepared. The morphologies of ZnO and composite materials were characterized by scanning electron microscopy(SEM) a...Two different morphologies of ZnO(lotus-shaped, rod-shaped) and ZnO/PVDF composite materials were prepared. The morphologies of ZnO and composite materials were characterized by scanning electron microscopy(SEM) and transmission electron microscopy(TEM). Fourier transform infrared spectroscopy(FT-IR), thermal gravimetry(TG), and X-ray diffraction(XRD) were also used to characterize the chemical structures and phase composites of ZnO and ZnO/PVDF composite materials. Breakdown voltage, dielectric constant and dielectric loss of ZnO/PVDF composite materials were also tested. Microstructure analysis showed that ZnO nanoparticles dispersed uniformly in the matrix. And the dielectric constant expresses a significantly improvement while the dielectric loss and breakdown voltage expresses no significant change. Moreover, dielectric constant keeps an improvement tendency with increasing content of ZnO.展开更多
Spinel-type CuFe_(2)O_(4)nanoparticles were syn-thesized by a solvother-mal method using ethy-lene glycol as solvent and polyvinylpyrroli-done(PVP)as disper-sant.The characteriza-tion results showed that the average d...Spinel-type CuFe_(2)O_(4)nanoparticles were syn-thesized by a solvother-mal method using ethy-lene glycol as solvent and polyvinylpyrroli-done(PVP)as disper-sant.The characteriza-tion results showed that the average diameter of the hollow-spherical CuFe_(2)O_(4)was approximately 100 nm with homogeneous morphology and negligible agglomeration.CuFe_(2)O_(4)was used as the active electrode material to explore its su-percapacitive properties in different concentrations of KOH electrolytes.It was found that the CuFe_(2)O_(4)hollow-spherical nanoparticles exhibit potential electronic performance in superca-pacitor,with a specific capacitance of 368.2 F/g and capacitance stability retention of 91.0%after 2000 cycles at the current density of 5 A/g in 3 mol/L KOH electrolyte.The present findings demonstrate that the CuFe_(2)O_(4)electrode materials can have important implications with practical prospects in energy storage systems.展开更多
The effects of MgO and TiO_2 on the viscosity, activation energy for viscous flow, and break-point temperature of titanium-bearing slag were studied. The correlation between viscosity and slag structure was analyzed b...The effects of MgO and TiO_2 on the viscosity, activation energy for viscous flow, and break-point temperature of titanium-bearing slag were studied. The correlation between viscosity and slag structure was analyzed by Fourier transform infrared(FTIR) spectroscopy. Subsequently, main phases in the slag and their content changes were investigated by X-ray diffraction and Factsage 6.4 software package. The results show that the viscosity decreases when the MgO content increases from 10.00wt% to 14.00wt%. Moreover, the break-point temperature increases, and the activation energy for viscous flow initially increases and subsequently decreases. In addition, with increasing TiO_2 content from 5.00wt% to 9.00wt%, the viscosity decreases, and the break-point temperature and activation energy for viscous flow initially decrease and subsequently increase. FTIR analyses reveal that the polymerization degree of complex viscous units in titanium-bearing slag decreases with increasing MgO and TiO_2 contents. The mechanism of viscosity variation was elucidated. The basic phase in experimental slags is melilite. Besides, as the MgO content increases, the amount of magnesia–alumina spinel in the slag increases. Similarly, the sum of pyroxene and perovskite phases in the slag increases with increasing TiO_2 content.展开更多
基金the State Key Fundamental Research Program(Ministry of Science and Technology of China,No.2011CBA00501)Shanghai Municipal Science and Technology Commission,China(Grant No:11DZ1200300)the Foundation of State Key Laboratory of Coal Conversion(Grant No:1112610)
文摘Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2+OH and C6+OH in alcohol distribution was very high while the methane product fraction in hydrocarbon distribution was rather low, demonstrating a promising potential in higher alcohols synthesis from syngas. The distribution of alcohols and hydrocarbons approximately obeyed Anderson-Schulz-Flory distribution with similar chain growth probability, indicating alcohols and hydrocarbons derived from the same intermediates. The effects of Cu/Fe molar ratio, reaction temperature and gas hourly space velocity (GHSV) on catalytic performance were studied in detail. The sample with a Cu/Fe molar ratio of 10/1 exhibited the best catalytic performance. Higher reaction temperature accelerated water-gas-shift reaction and led to lower total alcohols selectivity. GHSV showed great effect on catalytic performance and higher GHSV increased the total alcohol selectivity, indicating there existed visible dehydration reaction of alcohol into hydrocarbon.
基金Supported by National Natural Science Foundation of China(Nos.50378004 and 50678007)Beijing Natural Science Foun-dation(No.8082009)+1 种基金Science & Technology Development Programme of Beijing Municipal Commission of Education (No.KM200610005025)Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality(No. 05004014200701).
文摘Iron-manganese composited oxide(FeMnO) was prepared with potassium permanganate and ferrous salt. Interface performance, charge property and structure topography of the FeMnO were investigated. Coagulation efficiency and pollution removal mechanism of the FeMnO were approached. Results show that the main compositions of the FeMnO are δ-manganese dioxide and ferric hydroxide. The specific surface area is about 146.22 m^2/g. The FeMnO contains rich hydroxyl with extremely strong adsorption action and chemical adsorption activity. The zero charge point of the oxide in pure water is about 8.0 of pH value. Under neutral pH value conditions, the FeMnO particle surface carried positive charges. The FeMnO particles are quasi-spherical micro-particles with irregular sizes adjoined each other to form net construction. Phosphorus removal efficiency of the FeMnO is remarkable, the total dissoluble phosphorus of settled water can be reduced below detecting level(0.3 μtg/L) at a FeMnO dosage of 6 mg/L, and total phosphorus below detecting level at a FeMnO dosage of 10 mg/L, for water samples containing total phos- phorus of 1281.70 μg/L and total dissoluble phosphorus of 1187.91 μtg/L. The mechanism of effective coagulation for phosphorus removal is combined results of multiple actions of adsorption, charge neutralization, adsorption/bridging and so on.
文摘A coating of composition Si-40Mo (wt pct) was prepared by fused slurry coating method on the two-dimensional carbon/carbon (2D-C/C) composite to improve oxidation resistance. In the procedure of the fabrication, pure St slurry inner layer in the pre-coating was necessary to apply because of infiltration of liquid Si into the substrate during the sintering. The coating consists of Si continuous phase and MoSi2 particles. In addition, the infiltration of Si into the substrate and the SiC reaction layer between the coating and the C/C composite were observed. Oxidation behavior of coated and uncoated C/C composites was studied in cyclic mode. The oxidation resistance and the thermal shock resistance of the Si-Mo fused slurry coating were quite excellent at 1370℃.
基金supported by the National Natural Science Foundation of China(Grants No.21067004 and No.21263005)the Technological Foundation of Jiangxi Province Education Office(No.GJJ12344)+1 种基金the Young Science and Technolgy Project of Jiangxi Province(No.20133BAB21003)the Young Scientist Training Project of Jiangxi Province(No.20122BCB23015)
文摘A series of novel Ni/CeOe-Al2O3 composite catalysts were synthesized by one-step citric acid complex method, The as-synthesized catalysts were characterized by N2 physical adsorption/desorption, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, hydrogen temperature-programmed reduction (Hz-TPR), X-ray photoelectron spectroscopy (XPS) and thermogravimetry analysis (TGA). The effects of nickel content, calcination and reaction temperatures, gas hourly space velocity (GHSV) and inert gas dilution of N2 on their performance of catalytic partial oxidation of methane (CPOM) were investigated. Catalytic activity test results show that the highest methane conversion (〉85%), the best selectivities to carbon monoxide (〉87%) and to hydrogen (〉95%), the excellent stability and perfect Hz/CO ratio (2.0) can be obtained over Ni/CeO2-Al2O3 with 8 wt% Ni content calcined at 700 ℃ under the reaction condition of 750 ℃, CH4/O2 ratio of 2 : 1 and gas hourly space velocity of 12000 mL.h-1 .g-1. Characterization results show that the good catalytic performance of this composite catalyst can be contributed to its large specific surface area (~108 m2.g-1), small crystallite size, easy reducibility and low coking rate.
文摘CO2-TPD was demonstrated an effective way to investigate the phase formation during pyrolysis for the preparation of composite oxides using metal-organic molecules as precursors.Based on the CO2-TPD results, it was found that calcination condition had deep effect on the carbonate formation and the minimum firing temperature to acquire pure phase composite oxide.An optimized calcination schedule was then developed.
基金Supported by the Natural Science Foundation of Heilongjiang Province(No.9810B).
文摘A mesoporous Al-Mg composite oxide with a hexagonal structure was synthesized with aluminium nitrate and magnesium nitrate as the reagents and sodium dodecyl sulfate(SDS) as the template in the presence of ethylenediamine. The XRD, nitrogen adsorption-desorption and TEM studies indicate that the composite has a hexagonal framework structure and an average pore diameter of 2. 6 nm. The TG/DTA spectra indicate that the decomposition and the removal of the occluded surfactant of the sample take place in a range of 230-550 ℃. The mesoporous Al-Mg composite oxide exhibites a highly catalytic activity for the oxyethylation of fatty alcohols. Narrow-range distributed ethoxylates are formed in the presence of the mesoporous Al-Mg composite oxide catalyst. The distribution selectivity coefficient(Cx) is 24 when the mesoporous Al-Mg composite oxide was used as a catalyst for the oxyethylation of octanol and the average adduct degree of ethoxylates is 6. 4.
文摘Oxidation behavior of C/C-SiC gradient matrix composites and C/C composites were compared in stationary air. The results show that oxidation threshold of C-SiC materials increases with the amount of SiC particles in the codeposition matrix. Oxidation rate of C/C-SiC gradient matrix composites is significantly lower than that of C/C material. The micro-oxidation process was observed by SEM.
基金the National Natural Science Foundation of China (No.51274039)the State Key Lab of Advanced Metals and Materials (No.2013-ZD05)the Guangdong Foundation of Research (No.2014B090901003)
文摘Fe3O4@SiO2 core–shell composite nanoparticles were successfully prepared by a one-pot process. Tetraethyl-orthosilicate was used as a surfactant to synthesize Fe3O4@SiO2 core–shell structures from prepared Fe3O4 nanoparticles. The properties of the Fe3O4 and Fe3O4@SiO2 composite nanoparticles were studied by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The prepared Fe3O4 particles were approximately 12 nm in size, and the thickness of the SiO2 coating was approximately 4 nm. The magnetic properties were studied by vibrating sample magnetometry. The results show that the maximum saturation magnetization of the Fe3O4@SiO2 powder(34.85 A·m^2·kg^–1) was markedly lower than that of the Fe3O4 powder(79.55 A·m^2·kg^–1), which demonstrates that Fe3O4 was successfully wrapped by SiO2. The Fe3O4@SiO2 composite nanoparticles have broad prospects in biomedical applications; thus, our next study will apply them in magnetic resonance imaging.
基金supported by the National Natural Science Foundation of China(Grant Nos.61222501 and 61335004)
文摘The electrical and optical properties of the indium tin oxide (ITO)/epoxy composite exhibit dramatic variations as functions of the ITO composition and ITO particle size. Sharp increases in the conductivity in the vicinity of a critical volume fraction have been found within the framework of percolation theory. A conductive and insulating transition model is extracted by the ITO particle network in the SEM image, and verified by the resistivity dependence on the temperature. The dependence of the optical transmittance on the particle size was studied. Further decreasing the ITO particle size could further improve the percolation threshold and light transparency of the composite film.
基金Funded by National Natural Science Foundation of China(No.50702045)the Program for New Century Excellent Talents in University(No.NCET-08-0460)Basic Research Foundation of NWPU(No.JC20100227)
文摘The fracture toughness of a carbon/carbon composites oxidized at different temperature for 1 h was measured. The fracture surfaces were examined by scanning electron microscopy (SEM). The results indicate that oxidation temperature has significant effects on the fracture toughness. Fracture toughness decreases with the increase of the weight loss. The SEM images reveal that the decrease of fracture toughness was mainly attributed to the oxidation of the interface in the composite.
基金Funded by Science and Technology Commission of Shanghai Municipality (No.0952nm02500)
文摘A series of composites as electrode materials for supercapacitors were prepared via incipient wetness impregnation method utilizing ordered mesoporous carbon (OMC) and tin (IV) oxide (SnO2) with different ratio.The structure and electrochemical properties of the OMC/SnO2 composites were characterized by XRD,TEM and cyclic voltammetry (CV).Pore characteristics were measured by nitrogen adsorption and desorption isotherms.The results show that the structure and electrochemical properties of the composites depend mainly on the loading amount of SnO2 in the ordered mesoporous carbon.The optimum amount of SnCl4 added is found to be 40 % (1.54 g ethanol-based SnCl4·5H2O added to 1 g OMC) of the saturated solution.The specific capacitance of the composite of optimum amount of SnCl4 (200 F g-1) is nearly three times of that of the pristine SnO2 (72 F g-1) at the scan rate of 5 mV s-1,and its specific capacitance is almost equal to that of the ordered mesoporous carbon (126 F g-1) at the scan rate of 200 mV s-1.Meanwhile,it has better specific volumetric energy density than OMC due to its higher density.Besides,in the potential range of 0-0.9 V the composite electrode material exhibits a stable cycle life after 500 cycles.
基金Funded by the Science and Technology Key Fund Project of Shanghai University of Engineering Science(cs1405015)the Graduate Research and Innovation Special Projects of Shanghai University of Engineering Science(15KY0501 and 14KY0515)
文摘YSZ/(Ni, Al) composite coatings with different Ni:Al mole ratios were deposited on superalloy Inconel 600 by electrophoretic deposition(EPD) technique, followed by sintering in CH_4 atmosphere at 1 100 ℃for 2 h and isothermally oxidation at 1000 ℃ for 50 h. After sintering at 1100 ℃ for 2 h in CH_4 atmosphere, besides ZrC and t-ZrO_2 phases, the phase constitutes of Ni:Al mole ratios with 1:3, 1:2, and 1:1 were(Zr, Al)C, AlNi_3 and Ni phases, respectively. A remarkable difference in the oxidation behaviors of YSZ/(Ni, Al) composite coatings with different Ni:Al mole ratios was observed. For YSZ(Ni:Al=1:3) coated sample, oxidation at 1000 ℃ causes decomposition of the(Zr,Al)C solid solution to metallic Al, and then most of the Al is oxidized to Al_2O_3. For the YSZ(Ni:Al=1:2) coated sample, oxidation at 1000 ℃ mainly causes decomposition of the AlNi_3 phase. For YSZ(Ni:Al=1:1) coated sample, after oxidation at 1000 ℃, most of the Ni is oxidized to Ni O phase, and tolerated 50 h of oxidation and finally cracked and spalled from the specimen. YSZ(Ni:Al=1:3) and YSZ(Ni:Al=1:2) coated samples show superior oxidation resistance than that of YSZ coating. The different oxidation resistance mechanisms of YSZ/(Ni, Al) composite coatings sintered in CH_4 atmosphere were discussed.
基金Founded by the National Natural Youth Science Fundation of China(51301086)the Scientific Research Fund of Nanjing Institute of Technology Doctoral(N20130222 and CKJB201205)the Nanjing Institute of Technology,China
文摘Pure copper plates were coated by Ni-TiC dipulse current plating method. The effects of adding different concentration(ranging from 0.5 g/L to 3.0 g/L) of attapulgite nano particles to the plating bath on the surface morphology, wear resistance, and oxidation resistance of Ni/TiC/Attapulgite nano-composite coatings were investigated. The experimental results show that the composite coating is flat and compact with adding 3.0 g/L in the bath, and the coating preferred orientation is changed from the planes(111) to(200). The coefficient of the composite coatings decreases from 0.68 to 0.18 with increasing content of attapulgite in the bath, a mixed mode of adhesive-abrasive wear occurs for all coatings, and the wear mechanism shows a transition from adhesive-abrasive to predominantly abrasive wear mechanism when the concentration of attapulgite is beyond 1.5 g/L in electrolyte. The oxidation resistance of composite coatings is the best prepared when adding attapulgite particles at 0.5 g/L in the bath, the oxide mainly consists of a NiO phase by X-ray analysis.
基金This project was supported by the National Natural Science Foundation of China (1972003).
文摘With sol-gel method, nanometer La-Ti composite oxide was successfully prepared at a low temperature (750~800C) using polyethylene glycol as dispersant. By means of atomic force microscope, the surface pattern, particle size distribution, and specific surface area were studied. The compound particle surface appears as a smooth sheet, the mean size of the compound is 25.38 nm. On the specific surface, the particle erects at a height of 4.69 nm. The surface area is 58.90 nm2. The La-Ti composite oxide nanocrystal prefers to narrow and even particle size distribution and the homogeneity of surface topography.
文摘Two methods for preparing La0.9K0.1CoO3 perovskite composite oxides.traditional solid state reaction method and sol-gel method.were compared.The characteristics of the powders,such as purity.particle diameter,BET surface area,pore diameter,were inrestigated by using TG-DTA,XRD,SEM and BET methods.The experimental results shou that La0.9K0.1CoO3 perorskite composite oxide can be obtained by using the two methods.The purity of La0.9K0.1CoO3 powders can be increased by raising the calcining temperature while the particle diameter increased and BET surface area decreased.At the same calcining temperature,the properties of the La0.9K0.1CoO3 powders synthesized by the sol-gel method are superior to those synthesized by the solid state reaction method.such as purer phase,smaller particle diameter,which can be used as a satisfactory catalyst in diesel waste gas cleaning.
文摘The composition,structure and micro-morphology of magnesium- iron- aluminum composite oxides were investigated using various methods such as XRF,SEM,EDS,XRD and KMn O4-titration. Compared to hercynite,the composite oxides have completely different phases including solid solution( Mg O)0. 77( Fe O)0. 23,composite spinel Mg Fe0. 2Al1. 8O4 and a small amount of Mg Fe2O4. The composite oxides exhibit excellent corrosion resistance to cement clinker and potassium salts.The products produced by magnesite and the composite oxides show better performance than magnesia- hercynite bricks,especially the corrosion resistance and thermal shock resistance.
基金National Natural Science Foundation of China (50372037)Scientific Research Foundations of Shaanxi University of Science and Technology (SUST-B14)
文摘SiCp/Al2O3-Al composites were synthesized by means of direct metal oxidation method. The composition and microstructures of the composites were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and metallurgical microscope. The effects of technical parameters on the properties of the product were analyzed. The results indicate that the composite possesses a dense microstructure, composed of three interpenetrated phases. Of them, SiO2 layer prohibits the powdering of the composites; Mg promotes the wetting and infiltration of the system and Si restricts the interfacial reaction while improving the wetting ability between reinforcement and matrix.
基金Funded by the National Natural Science Foundation of China(51677045)the Natural Science Foundation of Heilongjiang Province of China(E201224)
文摘Two different morphologies of ZnO(lotus-shaped, rod-shaped) and ZnO/PVDF composite materials were prepared. The morphologies of ZnO and composite materials were characterized by scanning electron microscopy(SEM) and transmission electron microscopy(TEM). Fourier transform infrared spectroscopy(FT-IR), thermal gravimetry(TG), and X-ray diffraction(XRD) were also used to characterize the chemical structures and phase composites of ZnO and ZnO/PVDF composite materials. Breakdown voltage, dielectric constant and dielectric loss of ZnO/PVDF composite materials were also tested. Microstructure analysis showed that ZnO nanoparticles dispersed uniformly in the matrix. And the dielectric constant expresses a significantly improvement while the dielectric loss and breakdown voltage expresses no significant change. Moreover, dielectric constant keeps an improvement tendency with increasing content of ZnO.
基金supported by Henan Province Key Research and Development and Promotion of Science and Technology Project(No.222102320336)Applica-tion Research Plan of Key Scientific Research Projects of Higher Education Institutions of Henan Province(No.22B150018)the National Natural Science Foundation of China(No.92061203)。
文摘Spinel-type CuFe_(2)O_(4)nanoparticles were syn-thesized by a solvother-mal method using ethy-lene glycol as solvent and polyvinylpyrroli-done(PVP)as disper-sant.The characteriza-tion results showed that the average diameter of the hollow-spherical CuFe_(2)O_(4)was approximately 100 nm with homogeneous morphology and negligible agglomeration.CuFe_(2)O_(4)was used as the active electrode material to explore its su-percapacitive properties in different concentrations of KOH electrolytes.It was found that the CuFe_(2)O_(4)hollow-spherical nanoparticles exhibit potential electronic performance in superca-pacitor,with a specific capacitance of 368.2 F/g and capacitance stability retention of 91.0%after 2000 cycles at the current density of 5 A/g in 3 mol/L KOH electrolyte.The present findings demonstrate that the CuFe_(2)O_(4)electrode materials can have important implications with practical prospects in energy storage systems.
基金financial support by the Fundamental Research Funds for the Central Universities (No. N130602003)National High Technology Research and Development Program of China (No. 2012AA062302)the National Natural Science Foundation of China (No. 51574067)
文摘The effects of MgO and TiO_2 on the viscosity, activation energy for viscous flow, and break-point temperature of titanium-bearing slag were studied. The correlation between viscosity and slag structure was analyzed by Fourier transform infrared(FTIR) spectroscopy. Subsequently, main phases in the slag and their content changes were investigated by X-ray diffraction and Factsage 6.4 software package. The results show that the viscosity decreases when the MgO content increases from 10.00wt% to 14.00wt%. Moreover, the break-point temperature increases, and the activation energy for viscous flow initially increases and subsequently decreases. In addition, with increasing TiO_2 content from 5.00wt% to 9.00wt%, the viscosity decreases, and the break-point temperature and activation energy for viscous flow initially decrease and subsequently increase. FTIR analyses reveal that the polymerization degree of complex viscous units in titanium-bearing slag decreases with increasing MgO and TiO_2 contents. The mechanism of viscosity variation was elucidated. The basic phase in experimental slags is melilite. Besides, as the MgO content increases, the amount of magnesia–alumina spinel in the slag increases. Similarly, the sum of pyroxene and perovskite phases in the slag increases with increasing TiO_2 content.