NiO and Ce0.8Sm0.2O1.9 were synthesized by the combination of sol gel and citric acid-nitrate low temperature self-propagating combustion method. Anode precursors which include home-made NiO and Ce0.8Sm0.2O1.9 were pr...NiO and Ce0.8Sm0.2O1.9 were synthesized by the combination of sol gel and citric acid-nitrate low temperature self-propagating combustion method. Anode precursors which include home-made NiO and Ce0.8Sm0.2O1.9 were prepared by different NiO content and fabrication condition. The anode precursors with pure hydrogen at 820 ℃ for 2.5 h were reduced, The electrical conductivity was tested, and the effect of microstructure on electrical conductivity of Ce0.8Sm0.2O1.9 composite anodes was investigated. The results show that the anode electrical conductivity depends strongly on the anode microstructure that is dramatically affected by Ni content and fabrication condition.展开更多
Compositely doped oxide La0.5Sr0.5CoO2.91 （LSC） was synthesized using solid state reaction and citric acid-nitrate low temperature self-propagating combustion methods. The crystal structure and the particle size mic...Compositely doped oxide La0.5Sr0.5CoO2.91 （LSC） was synthesized using solid state reaction and citric acid-nitrate low temperature self-propagating combustion methods. The crystal structure and the particle size micrograph of LSC powders synthesized by different methods were investigated with XRD and SEM. The experimental results show that the single perovskite phase of LSC can be synthesized by solid state reaction method, but LaSrCoO4 phase appears in LSC powder synthesized by citric acid-nitrate low temperature self-propagating combustion method. The LSC particle by citric acid-nitrate low temperature self- propagating combustion method has smaller size. To analyze the character of cathode material based on Ceo.gGdo.101.95（GDC） electrolyte, two types of cathode wafers were fabricated with the two kinds of LSC and GDC powders at the mass rate of 6：4, respectively. The electrical conductivity of the sintered samples was measured by four probe DC method from 300 to 800 ℃. The cathode with LSC particle by citric acid- nitrate low temperature self-propagating combustion method has higher electrical conductivity. In order to investigate the stability, the two samples were put into the muffle furnace to heat up in air at 800℃for 800 h. To analysis the reason for reduced electrical conductivity, the crystal structure and the particle micrograph of the cathode wafers before and after an exposure were investigated with XRD and SEM. The result shows that new crystal structure appears in both the two kinds of cathode wafers and crystal micrographs change a lot.展开更多
The coal partial gasification process produces a large number of chars.They have similar combustion characteristics to anthracite and can be utilized as a material manufacturing clean briquette to replace residential ...The coal partial gasification process produces a large number of chars.They have similar combustion characteristics to anthracite and can be utilized as a material manufacturing clean briquette to replace residential coal to achieve clean combustion.Moreover,the coal partial gasification produced more tar at relatively low temperature,which can be applied as naphtha or diesel after purification and hydrogenation.Herein,experiments of coal partial gasification coproducing char,tar,and gas are carried out on a bench-scale fluidized bed reactor during the temperature range of 625–762℃.The effect of equivalence ratio on the characteristics of coal partial gasification products is studied.The results show that the equivalence ratio increasing from 0.06 to 0.13 leads to a higher partial gasification temperature and lower char yield,and tar yield reaches a maximum value and the lower calorific value of gas reaches as high as 6.14 MJ/m^(3).When the gasification temperature is lower than 643℃,the increase in temperature promotes the generation of oxygen-containing functional groups and aromatic compounds in coal particles,and the microstructures of char become more disordered.The combustion stability of char is getting worse,whereas the pore structures in char become abundant at high temperatures.From the analysis of the tar chromatography column,it is observed that asphaltene and non-hydrocarbon account for 77%–88%of the total amount of tar.展开更多
In this work,the effects of nanoparticle size,particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated.Both size and pH are found to significantly affect nanocollo...In this work,the effects of nanoparticle size,particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated.Both size and pH are found to significantly affect nanocolloid viscosity.Two models are used to study the effect of aggregate structure on the viscosity of the nanocolloidal dispersion.The fractal concept is introduced to describe the irregular and dynamic aggregate structure.The structure of aggregates,which is considered to play an important role in viscosity,is affected by both intermolecular and electrostatic forces.The particle interaction is primarily affected by particle distance and becomes stronger with decreasing particle size and increasing volume fraction.The aggregate structure is also affected by the pH of the solution.Studying the relationship between pH and zeta-potential shows that with the neutralization of charges on the particle surface and decreasing electrical repulsion force,the particle interaction becomes dominated by attractive forces and the aggregates form a more compact structure.展开更多
The evolution behavior of the light tar fraction of tar during large bituminous coal particle pyrolysis in afluidized bed reactor at 500--900 ℃ was investigated to optimize the industrial process. The coal residence ...The evolution behavior of the light tar fraction of tar during large bituminous coal particle pyrolysis in afluidized bed reactor at 500--900 ℃ was investigated to optimize the industrial process. The coal residence time wasvaried from 30 s to 150 s. The crude tar obtained was distilled and separated into the light fraction and the heavyfraction through an evaporator under conditions of 280 ℃ and 104 Pa. The light tar was subjected to GC-MS analysis,and the 300 main species in each spectrum were determined and analyzed. The experimental results showed that theevolution behavior of the light tar fraction and the heavy tar fraction presented spectacularly different variation trendswith pyrolysis temperature and coal residence time. The molecular weight and number of rings per aromatic com-pound molecule contained in the light tar fraction increased with increasing pyrolysis temperature because of poly-merization. It was also observed that the amount of methyl substituents decreased with an increasing number of ringsper molecule of poly-aromatic ring compounds. The chain aliphatic compound evolution was suppressed and under-went heterocyclization with increasing temperature.展开更多
文摘NiO and Ce0.8Sm0.2O1.9 were synthesized by the combination of sol gel and citric acid-nitrate low temperature self-propagating combustion method. Anode precursors which include home-made NiO and Ce0.8Sm0.2O1.9 were prepared by different NiO content and fabrication condition. The anode precursors with pure hydrogen at 820 ℃ for 2.5 h were reduced, The electrical conductivity was tested, and the effect of microstructure on electrical conductivity of Ce0.8Sm0.2O1.9 composite anodes was investigated. The results show that the anode electrical conductivity depends strongly on the anode microstructure that is dramatically affected by Ni content and fabrication condition.
文摘Compositely doped oxide La0.5Sr0.5CoO2.91 （LSC） was synthesized using solid state reaction and citric acid-nitrate low temperature self-propagating combustion methods. The crystal structure and the particle size micrograph of LSC powders synthesized by different methods were investigated with XRD and SEM. The experimental results show that the single perovskite phase of LSC can be synthesized by solid state reaction method, but LaSrCoO4 phase appears in LSC powder synthesized by citric acid-nitrate low temperature self-propagating combustion method. The LSC particle by citric acid-nitrate low temperature self- propagating combustion method has smaller size. To analyze the character of cathode material based on Ceo.gGdo.101.95（GDC） electrolyte, two types of cathode wafers were fabricated with the two kinds of LSC and GDC powders at the mass rate of 6：4, respectively. The electrical conductivity of the sintered samples was measured by four probe DC method from 300 to 800 ℃. The cathode with LSC particle by citric acid- nitrate low temperature self-propagating combustion method has higher electrical conductivity. In order to investigate the stability, the two samples were put into the muffle furnace to heat up in air at 800℃for 800 h. To analysis the reason for reduced electrical conductivity, the crystal structure and the particle micrograph of the cathode wafers before and after an exposure were investigated with XRD and SEM. The result shows that new crystal structure appears in both the two kinds of cathode wafers and crystal micrographs change a lot.
基金supported by the National Key Research and Development Projects of China(2019YFE0100100-05).
文摘The coal partial gasification process produces a large number of chars.They have similar combustion characteristics to anthracite and can be utilized as a material manufacturing clean briquette to replace residential coal to achieve clean combustion.Moreover,the coal partial gasification produced more tar at relatively low temperature,which can be applied as naphtha or diesel after purification and hydrogenation.Herein,experiments of coal partial gasification coproducing char,tar,and gas are carried out on a bench-scale fluidized bed reactor during the temperature range of 625–762℃.The effect of equivalence ratio on the characteristics of coal partial gasification products is studied.The results show that the equivalence ratio increasing from 0.06 to 0.13 leads to a higher partial gasification temperature and lower char yield,and tar yield reaches a maximum value and the lower calorific value of gas reaches as high as 6.14 MJ/m^(3).When the gasification temperature is lower than 643℃,the increase in temperature promotes the generation of oxygen-containing functional groups and aromatic compounds in coal particles,and the microstructures of char become more disordered.The combustion stability of char is getting worse,whereas the pore structures in char become abundant at high temperatures.From the analysis of the tar chromatography column,it is observed that asphaltene and non-hydrocarbon account for 77%–88%of the total amount of tar.
基金supported by the Research Foundation of Science and Technology Department of Zhejiang Province,China (2009C21023)the China Postdoctoral Science Foundation (20080441248)
文摘In this work,the effects of nanoparticle size,particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated.Both size and pH are found to significantly affect nanocolloid viscosity.Two models are used to study the effect of aggregate structure on the viscosity of the nanocolloidal dispersion.The fractal concept is introduced to describe the irregular and dynamic aggregate structure.The structure of aggregates,which is considered to play an important role in viscosity,is affected by both intermolecular and electrostatic forces.The particle interaction is primarily affected by particle distance and becomes stronger with decreasing particle size and increasing volume fraction.The aggregate structure is also affected by the pH of the solution.Studying the relationship between pH and zeta-potential shows that with the neutralization of charges on the particle surface and decreasing electrical repulsion force,the particle interaction becomes dominated by attractive forces and the aggregates form a more compact structure.
文摘The evolution behavior of the light tar fraction of tar during large bituminous coal particle pyrolysis in afluidized bed reactor at 500--900 ℃ was investigated to optimize the industrial process. The coal residence time wasvaried from 30 s to 150 s. The crude tar obtained was distilled and separated into the light fraction and the heavyfraction through an evaporator under conditions of 280 ℃ and 104 Pa. The light tar was subjected to GC-MS analysis,and the 300 main species in each spectrum were determined and analyzed. The experimental results showed that theevolution behavior of the light tar fraction and the heavy tar fraction presented spectacularly different variation trendswith pyrolysis temperature and coal residence time. The molecular weight and number of rings per aromatic com-pound molecule contained in the light tar fraction increased with increasing pyrolysis temperature because of poly-merization. It was also observed that the amount of methyl substituents decreased with an increasing number of ringsper molecule of poly-aromatic ring compounds. The chain aliphatic compound evolution was suppressed and under-went heterocyclization with increasing temperature.
