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
The corrosion behavior of bulk metallic glasses(BMGs)(Fe41Co7Cr15Mo14C15B6Y2)100-xCrx(x=0,4,8,12,molar fraction,%)was investigated in1mol/L HCl aqueous solution with electrochemical tests.The electrochemical measureme...The corrosion behavior of bulk metallic glasses(BMGs)(Fe41Co7Cr15Mo14C15B6Y2)100-xCrx(x=0,4,8,12,molar fraction,%)was investigated in1mol/L HCl aqueous solution with electrochemical tests.The electrochemical measurements demonstrate that the passive current density of Fe-based amorphous alloy is reduced by about one order of magnitude,and meanwhile,the stability of passive film can be guaranteed by the Cr/Mo molar ratio.The Mott–Schottky(M–S)curves show that the passive film is the densest when the molar ratio of Cr/Mo is between1.37and1.69.X-ray photoelectron spectroscopy(XPS)analysis was performed to clarify chemical states of elements in the passive films.The results show that the corrosion resistance of the alloy is related to the molar ratio of Cr/Mo.The stability of passive film is determined by the synergistic action of Cr and Mo elements.The main component of the passive film is Cr3+oxide.When the potential is greater than0.5V(vs SCE),Mo6+ions play an important role in keeping the stability of the passive film.The appropriate molar ratio of Cr/Mo can reduce the dissolution rate of the passive film.展开更多
In order to improve the activity and eliminate some impurities, pretreatment was used before hydrothermal synthesis. The fly ash was mixed with an aqueous NaOH solution, the alkali melted fly ash was also adopted, whi...In order to improve the activity and eliminate some impurities, pretreatment was used 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 about 104 ℃, and the liquid/solid ratio was controlled at 6：1. In order to control Si/Al molar ratio, SiO2 or Al2O3 powers were added to the fly ash. The results of XRD and SEM show that the alkali melted can activate fly ash and eliminate its quartz and mullite, along with the improvement of Si/Al molar ratio and alkalinity. In addition, zeolite Na-A changes into sodalite gradually, and nepheline is the synthesized intermediate product. Those results were 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 ...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 （aK） 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 aK, 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 aK 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
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
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
Mercury pollution is created by coal combustion processes in multi-component systems.Adsorbent injection was identified as a potential strategy for capturing Hg^(0)from waste gases,with adsorbents serving as the prima...Mercury pollution is created by coal combustion processes in multi-component systems.Adsorbent injection was identified as a potential strategy for capturing Hg^(0)from waste gases,with adsorbents serving as the primary component.The hydro-thermal approach was used to synthesize a series of MnO_(x)-CeO_(x)nanorod adsorbents with varying Mn/Ce molar ratios to maximize the Hg^(0)capture capabilities.Virgin CeO,had weak Hg elimination activity;<8%Hg^(0)removal efficiency was obtained from 150℃to 250℃.With the addition of MnOr,the amount of surface acid sites and the relative concentration of Mn4+increased.This ensured the sufficient adsorption and oxidation of Hg while overcoming the limitations of restricted adsorbate-adsorbent interactions caused by the lower surface area,endowing MnO_(x)-CeO_(x)with increased Hg^(0)removal capac-ity.When the molar ratio of Mn/Ce reached 6/4,the adsorbent's Hg^(0)removal efficiency remained over 92%at 150℃and 200℃.As the molar ratio of Mn/Ce grew,the adsorbent's Hg^(0)elimination capacity declined due to decreased surface area,weakened acidity,and decreased activity of Mn^(4+);<75%Hg^(0)removal efficiency was reached between 150℃and 250℃for virgin MnOx.Throughout the overall Hg'elimination reactions,Mn4+and O.were in charge of oxidizing Hg^(0)to Hg^(0),with Ce^(4+)acting as a promoter to aid in the regeneration of Mn^(4+),Because of its limited adaptability to flue gas components,further optimization of the MnO_(x)-CeO_(x)nanorod adsorbent is required.展开更多
For a highly efficient recycling of a wastewater containing a high concentration of MgCl_(2),Al(Ⅲ)and P507 were scheduled to be removed in advance.In this study,the in-situ removal of Al(Ⅲ)and P507 from a high conce...For a highly efficient recycling of a wastewater containing a high concentration of MgCl_(2),Al(Ⅲ)and P507 were scheduled to be removed in advance.In this study,the in-situ removal of Al(Ⅲ)and P507 from a high concentration MgCl_(2)solution at different pH values and Al/P molar ratios was investigated.The results showed that P507 formed organic complexes of Al_(x)(OH)_y^(Z+)-P507 at pH of 2.0-4.0.At pH of 4.0-5.0,Al(Ⅲ)precipitated and transferred into Al(OH)_(3)with a flocculent amorphous morphology.Active sites on the Al(OH)_(3)surface enhanced the removal efficiency of P507.At pH of 6.0-6.5,Al(Ⅲ)and Mg(Ⅱ)formed layered crystalline Al(OH)_(3)and MgAl_(2)(OH)_(8with)small pore channels and fewer active sites,resulting in a reduced removal efficiency of P507.When the Al/P molar ratio exceeded 13 and the pH was between 4.0 and 5.0,the removal rates of both Al(Ⅲ)and P507 were higher than98%,while the concentration loss of Mg(Ⅱ)was only 0.2%-0.9%.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
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.
基金Project(51261021)supported by the National Natural Science Foundation of ChinaProject(KJLD13056)supported by the Science and Technology Landing Plan of Jiangxi Province,China
文摘The corrosion behavior of bulk metallic glasses(BMGs)(Fe41Co7Cr15Mo14C15B6Y2)100-xCrx(x=0,4,8,12,molar fraction,%)was investigated in1mol/L HCl aqueous solution with electrochemical tests.The electrochemical measurements demonstrate that the passive current density of Fe-based amorphous alloy is reduced by about one order of magnitude,and meanwhile,the stability of passive film can be guaranteed by the Cr/Mo molar ratio.The Mott–Schottky(M–S)curves show that the passive film is the densest when the molar ratio of Cr/Mo is between1.37and1.69.X-ray photoelectron spectroscopy(XPS)analysis was performed to clarify chemical states of elements in the passive films.The results show that the corrosion resistance of the alloy is related to the molar ratio of Cr/Mo.The stability of passive film is determined by the synergistic action of Cr and Mo elements.The main component of the passive film is Cr3+oxide.When the potential is greater than0.5V(vs SCE),Mo6+ions play an important role in keeping the stability of the passive film.The appropriate molar ratio of Cr/Mo can reduce the dissolution rate of the passive film.
基金Supported by the Henan Outstanding Youth Science Fund (0612002400)
文摘In order to improve the activity and eliminate some impurities, pretreatment was used 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 about 104 ℃, and the liquid/solid ratio was controlled at 6：1. In order to control Si/Al molar ratio, SiO2 or Al2O3 powers were added to the fly ash. The results of XRD and SEM show that the alkali melted can activate fly ash and eliminate its quartz and mullite, along with the improvement of Si/Al molar ratio and alkalinity. In addition, zeolite Na-A changes into sodalite gradually, and nepheline is the synthesized intermediate product. Those results were 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 （aK） 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 aK, 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 aK 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.
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the Fundamental Research Funds in China Jiliang University,the Zhejiang Provincial Department of Education General Research Project in 2023(No.Y202353660)the Zhejiang Provincial Natural Science Foundation of China(No.LQ22E060003).
文摘Mercury pollution is created by coal combustion processes in multi-component systems.Adsorbent injection was identified as a potential strategy for capturing Hg^(0)from waste gases,with adsorbents serving as the primary component.The hydro-thermal approach was used to synthesize a series of MnO_(x)-CeO_(x)nanorod adsorbents with varying Mn/Ce molar ratios to maximize the Hg^(0)capture capabilities.Virgin CeO,had weak Hg elimination activity;<8%Hg^(0)removal efficiency was obtained from 150℃to 250℃.With the addition of MnOr,the amount of surface acid sites and the relative concentration of Mn4+increased.This ensured the sufficient adsorption and oxidation of Hg while overcoming the limitations of restricted adsorbate-adsorbent interactions caused by the lower surface area,endowing MnO_(x)-CeO_(x)with increased Hg^(0)removal capac-ity.When the molar ratio of Mn/Ce reached 6/4,the adsorbent's Hg^(0)removal efficiency remained over 92%at 150℃and 200℃.As the molar ratio of Mn/Ce grew,the adsorbent's Hg^(0)elimination capacity declined due to decreased surface area,weakened acidity,and decreased activity of Mn^(4+);<75%Hg^(0)removal efficiency was reached between 150℃and 250℃for virgin MnOx.Throughout the overall Hg'elimination reactions,Mn4+and O.were in charge of oxidizing Hg^(0)to Hg^(0),with Ce^(4+)acting as a promoter to aid in the regeneration of Mn^(4+),Because of its limited adaptability to flue gas components,further optimization of the MnO_(x)-CeO_(x)nanorod adsorbent is required.
基金financial supports from the National Key Research and Development Program of China(No.2022YFB3504501)the National Natural Science Foundation of China(Nos.52274355,91962211)the Gansu Province Science and Technology Major Special Project,China(No.22ZD6GD061)。
文摘For a highly efficient recycling of a wastewater containing a high concentration of MgCl_(2),Al(Ⅲ)and P507 were scheduled to be removed in advance.In this study,the in-situ removal of Al(Ⅲ)and P507 from a high concentration MgCl_(2)solution at different pH values and Al/P molar ratios was investigated.The results showed that P507 formed organic complexes of Al_(x)(OH)_y^(Z+)-P507 at pH of 2.0-4.0.At pH of 4.0-5.0,Al(Ⅲ)precipitated and transferred into Al(OH)_(3)with a flocculent amorphous morphology.Active sites on the Al(OH)_(3)surface enhanced the removal efficiency of P507.At pH of 6.0-6.5,Al(Ⅲ)and Mg(Ⅱ)formed layered crystalline Al(OH)_(3)and MgAl_(2)(OH)_(8with)small pore channels and fewer active sites,resulting in a reduced removal efficiency of P507.When the Al/P molar ratio exceeded 13 and the pH was between 4.0 and 5.0,the removal rates of both Al(Ⅲ)and P507 were higher than98%,while the concentration loss of Mg(Ⅱ)was only 0.2%-0.9%.
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.
