Formation, solution and phase change of hydration products in MgO-MgCl2-H2O system was studied with thermodynamics method, and resistance to water immersion and phase change of magnesium oxychloride cement with differ...Formation, solution and phase change of hydration products in MgO-MgCl2-H2O system was studied with thermodynamics method, and resistance to water immersion and phase change of magnesium oxychloride cement with different MgO/MgCl2 molar ratio was experimented. The results show that pH value of immersion solution of cement paste has a remarkable influence on phase stability of hydration products. A higher pH value leads to a lower solubility and a better phase stability of hydration products. When the solution pH value is higher than 10.37, the precipitation of much Mg（OH）2 crystal induces a worse phase stability of hydration products. With the increasing MgO/MgCl2 molar ratio （lower than 6）, the more amount of MgO in the hydration products enhances the alkalinity of solution and the phase stability is improved. However, when the MgO/MgCl2 molar ratio is higher than 6 and the excessive MgO exsits in the hydration products, the cement paste may be damaged by the excessive crystallization stress of a great deal of Mg（OH）2 formation.展开更多
Amorphous gels were processed with a varying Fe/Ba ratio of 11/5, 28/2, 10.5/1 in water and Solvent. Iron and barium nitrites with specific molar ratio was solved in water and slovent at 60°C for 3 hours until! a...Amorphous gels were processed with a varying Fe/Ba ratio of 11/5, 28/2, 10.5/1 in water and Solvent. Iron and barium nitrites with specific molar ratio was solved in water and slovent at 60°C for 3 hours until! a dark brown solution was prepared . The sols were introduced to substrate dropwise and spinning with 2000 rpm in 3 min was applied ; the work was repeated for 10 times and the samples were dried and sintered . The TGA analysis was used to identify the heating rate of the samples; at temperature of 1150°c for one hour the final phase was attained . the thickness , uniformity , morphology and the composition were examined by SEM and XRD. The study shows that the fabrication barium ferrite film of the molar ratio of Fe/Ba = 10.5/1 is much more suitable than other ratios .展开更多
In order to improve the activity and eliminate some impurities, pretreatment wasused before hydrothermal synthesis. The fly ash was mixed with an aqueous NaOH solution, the alkali melted fly ash was also adopted, whic...In order to improve the activity and eliminate some impurities, pretreatment wasused before hydrothermal synthesis. The fly ash was mixed with an aqueous NaOH solution, the alkali melted fly ash was also adopted, which is hydrothermally treated at about104^(。)C, and the liquid/solid ratio was controlled at 6:1. In order to control Si/AI molar ratio,SiO_2 or AI_2O_3 powers were added to the fly ash. The results of XRD and SEM show thatthe alkali melted can activate fly ash and eliminate its quartz and mullite, along with theimprovement of Si/AI molar ratio and alkalinity. In addition, zeolite Na-A changes into sodalite gradually, and nepheline is the synthesized intermediate product. Those resultswere discussed on the basis of a formation mechanism of zeolite from fly ash.展开更多
Fine Al(OH)3 crystals were aggregated from supersaturated aluminate solution in the batch reaction tanks. By means of laser particle size analyzer and scanning electron microscopy, the influences of temperature and in...Fine Al(OH)3 crystals were aggregated from supersaturated aluminate solution in the batch reaction tanks. By means of laser particle size analyzer and scanning electron microscopy, the influences of temperature and initial molar ratio of Na2O to Al2O3 (αK) on agglomeration of fine seed in Bayer process were investigated. The results show that agglomeration is almost finished in 8 h, and seeds with size less than 2 μm are easily aggregated together, and almost disappear in 8 h under the optimal process conditions. In the aluminate solution with the same moderate initial αK, when the reaction temperature reaches 75 ℃, the secondary nucleation does not occur, and the effect of agglomeration is better. And at the same reaction temperature, when the initial αK is 1.62, the initial supersaturation of aluminate solution is moderate, the binders on the surfaces of the seed are enough to maintain the agglomeration process, and the agglomeration degree is better. From SEM images, agglomeration mainly occurs in the fine particles, the combinations among the fine particles are loose and the new formed coarse crystal shapes are irregular.展开更多
Coordination complex of a copper cyanurate(Cu(Ⅱ)-CA) was transformed into coordination polymers upon the stimulus of extra Cu(Ⅱ) through “directed Ostwald ripening”. By increasing the molar ratio of Cu(Ⅱ) to CA, ...Coordination complex of a copper cyanurate(Cu(Ⅱ)-CA) was transformed into coordination polymers upon the stimulus of extra Cu(Ⅱ) through “directed Ostwald ripening”. By increasing the molar ratio of Cu(Ⅱ) to CA, we obtained two coordination polymers with selective coordination sites: Cu(Ⅱ)-κ N(HCA)κ NCu(Ⅱ) and Cu(Ⅱ)-κ N(HCA)κ O-Cu(Ⅱ), which display disparate magnetic interactions.展开更多
An aluminum fractionation study was conducted for a surface reservoir water treatment to understand the performance of poly- aluminum-silicate-chloride （PASiC） in terms of the residual A1 fractions as a function of ...An aluminum fractionation study was conducted for a surface reservoir water treatment to understand the performance of poly- aluminum-silicate-chloride （PASiC） in terms of the residual A1 fractions as a function of initial pH. The coagulation performance expressed as turbidity and organic matter removal was established as supporting data. Some extra data were evaluated in terms of the residual A1 ratio of the composite PASiC coagulant. The main residual A1 sources were the A1 fractions derived from the use of PASiC. The turbidity and organic matter removal ability was optimal at initial pH 6.00-7.00, while the concentrations of various residual A1 species and the residual A1 ratio of PASiC were minimal at an initial pH range of 7.00-8.00. Under the conditions of OH/AI molar ratio = 2.00 and Si/A1 molar ratio = 0.05, PASiC had superior coagulation performance and comparatively low residual A1 concentrations. The A1 fraction in the composite PASiC coagulant seldom remained under such conditions. Experimental data also indicated that the suspended （filterable） AI fraction was the dominant species, and organic-bound or organo-A1 complex A1 was considered to be the major species of dissolved A1 in water treated by PASiC coagulation. Additionally, the dissolved inorganic monomeric A1 species dominated the dissolved monomeric A1 fraction.展开更多
To promote the utilization efficiency of coal resources,and to assist with the control of sulphur during gasification and/or downstream processes,it is essential to gain basic knowledge of sulphur transformation assoc...To promote the utilization efficiency of coal resources,and to assist with the control of sulphur during gasification and/or downstream processes,it is essential to gain basic knowledge of sulphur transformation associated with gasification performance.In this research we investigated the influence of O_2/C molar ratio both on gasification performance and sulphur transformation of a low rank coal,and the sulphur transformation mechanism was also discussed.Experiments were performed in a circulating fluidized bed gasifier with O_2/C molar ratio ranging from 0.39 to 0.78 mol/mol.The results showed that increasing the O_2/C molar ratio from 0.39 to 0.78 mol/mol can increase carbon conversion from 57.65%to 91.92%,and increase sulphur release ratio from 29.66%to63.11%.The increase of O_2/C molar ratio favors the formation of H_2S,and also favors the retained sulphur transforming to more stable forms.Due to the reducing conditions of coal gasification,H_2S is the main form of the released sulphur,which could be formed by decomposition of pyrite and by secondary reactions.Bottom char shows lower sulphur content than fly ash,and mainly exist as sulphates.X-ray photoelectron spectroscopy(XPS)measurements also show that the intensity of pyrite declines and the intensity of sulphates increases for fly ash and bottom char,and the change is more obvious for bottom char.During CFB gasification process,bigger char particles circulate in the system and have longer residence time for further reaction,which favors the release of sulphur species and can enhance the retained sulphur transforming to more stable forms.展开更多
A series of CexZr1-xO2(0 B x B 1)with different molar ratios of Ce/Zr were syhthesized via coprecipitation method,and Fe2O3-WO3/CexZr1-xO2monolithic catalysts were prepared for selective catalytic reduction of nitroge...A series of CexZr1-xO2(0 B x B 1)with different molar ratios of Ce/Zr were syhthesized via coprecipitation method,and Fe2O3-WO3/CexZr1-xO2monolithic catalysts were prepared for selective catalytic reduction of nitrogen oxides by ammonia(NH3-SCR).The structural properties and redox behavior of the catalysts were comprehensively characterized by N2physisorption,X-ray diffraction(XRD),X-ray photoelectron spectra(XPS),H2-temperature programmed reduction(H2-TPR)and activity measurement for NH3-SCR.The results showed that the NH3-SCR activities of the catalysts were gradually enhanced by increasing the molar ratios of Ce/Zr,especially the lowtemperature catalytic activity and the reaction temperature window.Fe2O3-WO3/Ce0.68Zr0.32O2monolithic catalyst presented the best NH3-SCR activity among the investigated catalysts,more than 90%NOxcould be removed in the temperature range of 247–454°C on the catalyst under the gas hourly space velocities of 30,000 h-1.And it always held more than 99%N2selectivity and less than 20 ppm(1 ppm=10-6L/L)N2O generation concentration between 200 and500°C,the catalyst also displayed its strong resistance of H2O and SO2.Good textural and structural properties,more surface Fe,Ce and active oxygen were together contributed to the excellent NH3-SCR performance of Fe2O3-WO3/Ce0.68Zr0.32O2catalyst.展开更多
The experimental test of co-incinerating Chinese raw municipal solid waste （MSW） and coal in a laboratory-scale tubular reactor was first reported in present study, and the emission of normal gas components and the ...The experimental test of co-incinerating Chinese raw municipal solid waste （MSW） and coal in a laboratory-scale tubular reactor was first reported in present study, and the emission of normal gas components and the effects of the S/Cl molar ratio or coal mixing percentages on polychlorinated dibenzo-p-dioxins and dibenzofurans （PCDDs/Fs） emission were investigated and discussed. The results indicated that OCDD was the only PCDD homologues since others like TCDD-HpCDD was hardly detected, while as the categories of PCDF homologues were comparatively much more general. The amount of PCDD was much larger than that of PCDF in all operating conditions. Since ZPCDF/∑PCDD〈〈1, the dominant role of the precursor formation was proven in our experimental conductions. With increasing the coal addition to MSW （from 0 to 16%）, PCDD and PCDF were reduced considerably. Coal and MSW may suppress the PCDD/F emissions efficiently （over 95%） during the MSW incineration process. The PCDD/F suppression results of the present study could be helpful guidance to the industrial application of Chinese MSW and auxiliary coal co-incineration processes. The PCDD/F stack emission data of two industrial incinerators using co-incineration technology in China seem to have a great positive reduction of PCDDs/Fs.展开更多
The amorphous boron nitride ceramic powders were prepared at 750-950 ℃ by the low-cost urea route, and the effects of preparation temperatures, molar ratios of the raw materials and oxidation treatment on the composi...The amorphous boron nitride ceramic powders were prepared at 750-950 ℃ by the low-cost urea route, and the effects of preparation temperatures, molar ratios of the raw materials and oxidation treatment on the composition, structure and surface morphology of the products were investigated through FT-IR, XRD and SEM. The results show that the products ceramize and crystallize gradually with the increase of the temperature. When the molar ratio and reaction temperature are 3：2 and 850 ℃, respectively, the products have high purity, compact structure and nice shape. The oxidation treatment at 450 ℃ will not impair the composition and structure of boron nitride but effectively remove the impurities.展开更多
Pure K2Ti4O9 whiskers were prepared by KDC（Kneading-Drying-Calcination） method with TiO2 and K2CO3 as raw materials. The influences of TiO2/K2CO3 molar ratio（RT/K）, calcination temperature（TC） and cooling proces...Pure K2Ti4O9 whiskers were prepared by KDC（Kneading-Drying-Calcination） method with TiO2 and K2CO3 as raw materials. The influences of TiO2/K2CO3 molar ratio（RT/K）, calcination temperature（TC） and cooling process on phase composition and morphology of the whiskers were investigated by TG-DSC（thermo gravimetric-differential scanning calorimeter）, XRD（X-ray diffraction）, and SEM（scanning electron microscope）. Pure K2Ti4O9 potassium titanate whiskers with large length-diameter ratio（r）（over 250） can be obtained at RT/K = 2.9 and TC = 950 ℃.展开更多
基金Funded by the National Natural Science Foundation of China(No50078019)
文摘Formation, solution and phase change of hydration products in MgO-MgCl2-H2O system was studied with thermodynamics method, and resistance to water immersion and phase change of magnesium oxychloride cement with different MgO/MgCl2 molar ratio was experimented. The results show that pH value of immersion solution of cement paste has a remarkable influence on phase stability of hydration products. A higher pH value leads to a lower solubility and a better phase stability of hydration products. When the solution pH value is higher than 10.37, the precipitation of much Mg（OH）2 crystal induces a worse phase stability of hydration products. With the increasing MgO/MgCl2 molar ratio （lower than 6）, the more amount of MgO in the hydration products enhances the alkalinity of solution and the phase stability is improved. However, when the MgO/MgCl2 molar ratio is higher than 6 and the excessive MgO exsits in the hydration products, the cement paste may be damaged by the excessive crystallization stress of a great deal of Mg（OH）2 formation.
文摘Amorphous gels were processed with a varying Fe/Ba ratio of 11/5, 28/2, 10.5/1 in water and Solvent. Iron and barium nitrites with specific molar ratio was solved in water and slovent at 60°C for 3 hours until! a dark brown solution was prepared . The sols were introduced to substrate dropwise and spinning with 2000 rpm in 3 min was applied ; the work was repeated for 10 times and the samples were dried and sintered . The TGA analysis was used to identify the heating rate of the samples; at temperature of 1150°c for one hour the final phase was attained . the thickness , uniformity , morphology and the composition were examined by SEM and XRD. The study shows that the fabrication barium ferrite film of the molar ratio of Fe/Ba = 10.5/1 is much more suitable than other ratios .
基金Supported by the Henan Outstanding Youth Science Fund (0612002400)
文摘In order to improve the activity and eliminate some impurities, pretreatment wasused before hydrothermal synthesis. The fly ash was mixed with an aqueous NaOH solution, the alkali melted fly ash was also adopted, which is hydrothermally treated at about104^(。)C, and the liquid/solid ratio was controlled at 6:1. In order to control Si/AI molar ratio,SiO_2 or AI_2O_3 powers were added to the fly ash. The results of XRD and SEM show thatthe alkali melted can activate fly ash and eliminate its quartz and mullite, along with theimprovement of Si/AI molar ratio and alkalinity. In addition, zeolite Na-A changes into sodalite gradually, and nepheline is the synthesized intermediate product. Those resultswere discussed on the basis of a formation mechanism of zeolite from fly ash.
基金Project(2005CB623702)supported by the Major State Basic Research and Development Program of ChinaProject(20476107) supported by the National Natural Science Foundation of China
文摘Fine Al(OH)3 crystals were aggregated from supersaturated aluminate solution in the batch reaction tanks. By means of laser particle size analyzer and scanning electron microscopy, the influences of temperature and initial molar ratio of Na2O to Al2O3 (αK) on agglomeration of fine seed in Bayer process were investigated. The results show that agglomeration is almost finished in 8 h, and seeds with size less than 2 μm are easily aggregated together, and almost disappear in 8 h under the optimal process conditions. In the aluminate solution with the same moderate initial αK, when the reaction temperature reaches 75 ℃, the secondary nucleation does not occur, and the effect of agglomeration is better. And at the same reaction temperature, when the initial αK is 1.62, the initial supersaturation of aluminate solution is moderate, the binders on the surfaces of the seed are enough to maintain the agglomeration process, and the agglomeration degree is better. From SEM images, agglomeration mainly occurs in the fine particles, the combinations among the fine particles are loose and the new formed coarse crystal shapes are irregular.
基金the financial support from the Australian Research Council (No.DP190101607)National Natural Science Foundation of China (No.21971203)。
文摘Coordination complex of a copper cyanurate(Cu(Ⅱ)-CA) was transformed into coordination polymers upon the stimulus of extra Cu(Ⅱ) through “directed Ostwald ripening”. By increasing the molar ratio of Cu(Ⅱ) to CA, we obtained two coordination polymers with selective coordination sites: Cu(Ⅱ)-κ N(HCA)κ NCu(Ⅱ) and Cu(Ⅱ)-κ N(HCA)κ O-Cu(Ⅱ), which display disparate magnetic interactions.
基金supported by the Scientific Technology Research and Development Program of Shandong,China (No.2010GZX20605)the Chinese National Foundation of Natural Sciences (No.21077066)+3 种基金the Natural Science Foundation of Shandong Province, China (No.ZR2010BM014)the Graduate Innovation Foundationof Shandong University (No.yyx10010, GIFSDU)the Shanghai Tongji Gao Tingyao Environmental Science &Technology Development Foundation (STGEF)the Scholarship Award for Excellent Doctoral Student granted by Ministry of Education
文摘An aluminum fractionation study was conducted for a surface reservoir water treatment to understand the performance of poly- aluminum-silicate-chloride （PASiC） in terms of the residual A1 fractions as a function of initial pH. The coagulation performance expressed as turbidity and organic matter removal was established as supporting data. Some extra data were evaluated in terms of the residual A1 ratio of the composite PASiC coagulant. The main residual A1 sources were the A1 fractions derived from the use of PASiC. The turbidity and organic matter removal ability was optimal at initial pH 6.00-7.00, while the concentrations of various residual A1 species and the residual A1 ratio of PASiC were minimal at an initial pH range of 7.00-8.00. Under the conditions of OH/AI molar ratio = 2.00 and Si/A1 molar ratio = 0.05, PASiC had superior coagulation performance and comparatively low residual A1 concentrations. The A1 fraction in the composite PASiC coagulant seldom remained under such conditions. Experimental data also indicated that the suspended （filterable） AI fraction was the dominant species, and organic-bound or organo-A1 complex A1 was considered to be the major species of dissolved A1 in water treated by PASiC coagulation. Additionally, the dissolved inorganic monomeric A1 species dominated the dissolved monomeric A1 fraction.
基金supported by the National Natural Science Foundation of China(No.21306193)the International Science&Technology Cooperation Program of China(No.2014DFG61680)
文摘To promote the utilization efficiency of coal resources,and to assist with the control of sulphur during gasification and/or downstream processes,it is essential to gain basic knowledge of sulphur transformation associated with gasification performance.In this research we investigated the influence of O_2/C molar ratio both on gasification performance and sulphur transformation of a low rank coal,and the sulphur transformation mechanism was also discussed.Experiments were performed in a circulating fluidized bed gasifier with O_2/C molar ratio ranging from 0.39 to 0.78 mol/mol.The results showed that increasing the O_2/C molar ratio from 0.39 to 0.78 mol/mol can increase carbon conversion from 57.65%to 91.92%,and increase sulphur release ratio from 29.66%to63.11%.The increase of O_2/C molar ratio favors the formation of H_2S,and also favors the retained sulphur transforming to more stable forms.Due to the reducing conditions of coal gasification,H_2S is the main form of the released sulphur,which could be formed by decomposition of pyrite and by secondary reactions.Bottom char shows lower sulphur content than fly ash,and mainly exist as sulphates.X-ray photoelectron spectroscopy(XPS)measurements also show that the intensity of pyrite declines and the intensity of sulphates increases for fly ash and bottom char,and the change is more obvious for bottom char.During CFB gasification process,bigger char particles circulate in the system and have longer residence time for further reaction,which favors the release of sulphur species and can enhance the retained sulphur transforming to more stable forms.
基金supported by the National Natural Science Foundation of China(21173153)the Project from Sichuan Provincial Environment Office of China(2011HB002)the National High Technology Research and Development Program of China(2013AA065304)
文摘A series of CexZr1-xO2(0 B x B 1)with different molar ratios of Ce/Zr were syhthesized via coprecipitation method,and Fe2O3-WO3/CexZr1-xO2monolithic catalysts were prepared for selective catalytic reduction of nitrogen oxides by ammonia(NH3-SCR).The structural properties and redox behavior of the catalysts were comprehensively characterized by N2physisorption,X-ray diffraction(XRD),X-ray photoelectron spectra(XPS),H2-temperature programmed reduction(H2-TPR)and activity measurement for NH3-SCR.The results showed that the NH3-SCR activities of the catalysts were gradually enhanced by increasing the molar ratios of Ce/Zr,especially the lowtemperature catalytic activity and the reaction temperature window.Fe2O3-WO3/Ce0.68Zr0.32O2monolithic catalyst presented the best NH3-SCR activity among the investigated catalysts,more than 90%NOxcould be removed in the temperature range of 247–454°C on the catalyst under the gas hourly space velocities of 30,000 h-1.And it always held more than 99%N2selectivity and less than 20 ppm(1 ppm=10-6L/L)N2O generation concentration between 200 and500°C,the catalyst also displayed its strong resistance of H2O and SO2.Good textural and structural properties,more surface Fe,Ce and active oxygen were together contributed to the excellent NH3-SCR performance of Fe2O3-WO3/Ce0.68Zr0.32O2catalyst.
基金Project supported by the National Basic Research Program (973) of China(No.G1999022211)the National Natural Science Foun-dation of China(No.59836210).
文摘The experimental test of co-incinerating Chinese raw municipal solid waste （MSW） and coal in a laboratory-scale tubular reactor was first reported in present study, and the emission of normal gas components and the effects of the S/Cl molar ratio or coal mixing percentages on polychlorinated dibenzo-p-dioxins and dibenzofurans （PCDDs/Fs） emission were investigated and discussed. The results indicated that OCDD was the only PCDD homologues since others like TCDD-HpCDD was hardly detected, while as the categories of PCDF homologues were comparatively much more general. The amount of PCDD was much larger than that of PCDF in all operating conditions. Since ZPCDF/∑PCDD〈〈1, the dominant role of the precursor formation was proven in our experimental conductions. With increasing the coal addition to MSW （from 0 to 16%）, PCDD and PCDF were reduced considerably. Coal and MSW may suppress the PCDD/F emissions efficiently （over 95%） during the MSW incineration process. The PCDD/F suppression results of the present study could be helpful guidance to the industrial application of Chinese MSW and auxiliary coal co-incineration processes. The PCDD/F stack emission data of two industrial incinerators using co-incineration technology in China seem to have a great positive reduction of PCDDs/Fs.
基金Funded by the National Natural Science Foundation of China (Nos.50902150 & 90916019)the Graduate Innovation Foundation of the National University of Defense Technology(No.S100103)
文摘The amorphous boron nitride ceramic powders were prepared at 750-950 ℃ by the low-cost urea route, and the effects of preparation temperatures, molar ratios of the raw materials and oxidation treatment on the composition, structure and surface morphology of the products were investigated through FT-IR, XRD and SEM. The results show that the products ceramize and crystallize gradually with the increase of the temperature. When the molar ratio and reaction temperature are 3：2 and 850 ℃, respectively, the products have high purity, compact structure and nice shape. The oxidation treatment at 450 ℃ will not impair the composition and structure of boron nitride but effectively remove the impurities.
基金Funded by the Natural Science Foundation Key Project of Hubei Province(No.2011CDA060)
文摘Pure K2Ti4O9 whiskers were prepared by KDC（Kneading-Drying-Calcination） method with TiO2 and K2CO3 as raw materials. The influences of TiO2/K2CO3 molar ratio（RT/K）, calcination temperature（TC） and cooling process on phase composition and morphology of the whiskers were investigated by TG-DSC（thermo gravimetric-differential scanning calorimeter）, XRD（X-ray diffraction）, and SEM（scanning electron microscope）. Pure K2Ti4O9 potassium titanate whiskers with large length-diameter ratio（r）（over 250） can be obtained at RT/K = 2.9 and TC = 950 ℃.
