A ternary composite of TiO2 and a SiO2-Al2O3 aerogel with good photocatalytic activity was prepared by a simple sol-gel method with TiO2 nanoparticles and SiO2-Al2O3 aerogels derived from industrial fly ash.The struct...A ternary composite of TiO2 and a SiO2-Al2O3 aerogel with good photocatalytic activity was prepared by a simple sol-gel method with TiO2 nanoparticles and SiO2-Al2O3 aerogels derived from industrial fly ash.The structural features of the TiO2/SiO2-Al2O3 aerogel composite were investigated by X-ray powder diffraction,Fourier transform infrared spectroscopy,transmission electron microscopy,gas adsorption measurements and diffuse reflectance UV-visible spectroscopy.The optimal conditions for photocatalytic degradation of 2-sec-butyl-4,6-dinitrophenol（DNBP],included an initial DNBP concentration of 0.167 mmol/L at pH = 4.86 with a catalyst concentration of 6 g/L,under visible light irradiation for 5 h.A plausible mechanism is proposed for the photocatalytic degradation of DNBP.Our composite showed higher photocatalytic activity for DNBP degradation than that of pure TiO2.This indicates that this material can serve as an efficient photocatalyst for degradation of hazardous organic pollutants in wastewater.展开更多
The crystallization behavior and kinetics of CaO-MgO-Al2O3 SiO2（CMAS） glass with the Fe2O3 content ranging from zero to 5%were investigated by differential scanning calorimetry（DSC）.The structure and phase analyse...The crystallization behavior and kinetics of CaO-MgO-Al2O3 SiO2（CMAS） glass with the Fe2O3 content ranging from zero to 5%were investigated by differential scanning calorimetry（DSC）.The structure and phase analyses were made by Fourier transform infrared spectroscopy（FT-IR） and X-ray diffraction（XRD）.The experiment results show that the endothermic peak temperature about 760℃ is associated with transition and the exothermic peak temperature about 1000℃ is associated with crystallization.The crystallization peak temperature decreases with increasing the Fe203 content.The crystallization mechanism is changed from two-dimensional crystallization to one-dimensional growth,and the intensity of diopside peaks becomes stronger gradually.There is a saltation for the crystallization temperature with the addition of 0.5%Fe2O3 due to the decomposition of Fe2O3.Si-O-Si,O-Si-O and T-O-T（T=Si,Fe,Al） linkages are observed in Fe2O3-CaO-MgO-Al2O3-SiO2 glass.展开更多
CaO-B203-SiO2 （CBS） glass powders are prepared by conventional glass melting method at different melting temperatures whose properties and microstructures are characterized by X-ray diffraction （XRD） and scanning ...CaO-B203-SiO2 （CBS） glass powders are prepared by conventional glass melting method at different melting temperatures whose properties and microstructures are characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It is found that there are SiO2 and some unknown phases in CBS glass melting liquid from 1 300 ℃ to 1 500 ℃ and the amount of these phases decreases with the increase of the melting temperature. The CBS glass melted at 1 450 ℃ could be sintered from 830 ℃ to 930 ℃ and the bulk densities of the samples are all higher than 2.4 g/cm^3. From the points of the properties and energy conservation, the melting temperature of 1 450 ℃ is the optimal melting temperature. The glass ceramic sintered at 850 ℃ exhibits better dielectric properties： er=6.33, tan6=2.2×10^-3 at 10 GHz, and the major phases of the samples are CaSiO3, CaB2O4 and SiO2.展开更多
The sintering characteristics at 1350℃ and leaching property at 80℃ of calcium aluminate clinkers in the CaO-Al2O3-SiO2 （C-A-S） system with different additions of FeO and Fe2O3 were investigated. FeO inhibits the ...The sintering characteristics at 1350℃ and leaching property at 80℃ of calcium aluminate clinkers in the CaO-Al2O3-SiO2 （C-A-S） system with different additions of FeO and Fe2O3 were investigated. FeO inhibits the conversion of β-Ca2SiO4 to γ-Ca2SiO4 and makes the clinker not pulverizable. FeO and Fe2O3 inhibit the formation of CaAl2O4, but promote the formation of Ca12Al14O33. The interplanar spacing at （2 1 1） crystal face of Ca12 Al14O33 in the clinker increases with the increase of FeO addition, which indicates that FeO forms solid solutions in Ca12Al14O33. The clinkers with Fe2O3 addition form a new phase Ca2Fe2O5, and the amount of Ca2Fe2o5 increases with the in crease of Fe2O3 addition. Both FeO and Fe2O3 do not affect the Al2O3 leaching rate of calcium aluminate clinker in sodium carbonate solution, but they increase the molar ratio of caustic Na2O to Al2O3 in the leached liquor.展开更多
A near infrared to visible blue, green, and red upconversion luminescence in a Tb^3＋-doped CaO-Al2O3-SiO2 glass was studied, which was excited using 800 nm femtosecond laser irradiation. The upconversion luminescence...A near infrared to visible blue, green, and red upconversion luminescence in a Tb^3＋-doped CaO-Al2O3-SiO2 glass was studied, which was excited using 800 nm femtosecond laser irradiation. The upconversion luminescence was attributed to ^5D3→^7F5, ^5D3→^7F4, ^5D3→^7F3, ^5D4→^7F6, ^5D4→^7F5, ^5D4→^7F4, and ^5D4→^7F3 transitions of Tb^3＋. The relationship between upconversion luminescence intensity and the pump power indicated that a three-photon simultaneous absorption process was dominant in this upconversion luminescence. The intense red, green, and blue upconversion luminescence of Tb^3＋-doped CaO-Al2O3-SiO2 glass may be potentially useful in developing three-dimensional display applications.展开更多
Ni/Al_2O_3-SiO_2 catalysts were synthesized via one-step method employing SiO_2 as an additive for the selective hydrogenation of butyne-1,4-diol(B_3D) to butane-1,4-diol(B1D). The prepared catalysts were evaluated by...Ni/Al_2O_3-SiO_2 catalysts were synthesized via one-step method employing SiO_2 as an additive for the selective hydrogenation of butyne-1,4-diol(B_3D) to butane-1,4-diol(B1D). The prepared catalysts were evaluated by a series of characterization techniques including BET, XRD, SEM, EDX-mapping, TEM, H_2-TPR, XPS, NH_3-TPD and Py-FTIR. Compared to Ni/Al_2O_3 catalyst, the SiO_2-doped samples exhibited better B_3D conversion. SiO_2 could help to form a strong interaction between NiO with the support, which inhibited Ni agglomeration at high temperature, improved the Ni dispersion, and enhanced the hydrogenation activity. B_1D selectivity was mainly influenced by the quantity of Lewis acid sites in addition to the Ni dispersion. The catalyst with a silica loading of 6.4% demonstrated an excellent selectivity of 75.18%(by 13% higher than the contrastive Ni/Al_2O_3 catalyst), which was attributed to the larger amount of Lewis acid sites and the moderate interaction between NiO with the support, which could facilitate the nickel dispersion on a preferable surface area of 176.3 m^2/g of support.展开更多
ZrO2, TiO2 and P2O5 were doped in CaO-B2O3-SiO2 glass-ceramics as nucleating additives. Effects of different nucleating additives on the phase separation and crystalline behaviors were investigated by using gradient t...ZrO2, TiO2 and P2O5 were doped in CaO-B2O3-SiO2 glass-ceramics as nucleating additives. Effects of different nucleating additives on the phase separation and crystalline behaviors were investigated by using gradient temperature furnace, DTA and XRD. Then, sintering process of the glass-ceramics was investigated by testing sintering shrinkage, dielectric constant and loss. The experimental results shows that the glass-ceramics doped with nucleating additives represents higher crystallization, with ZrO2 as an exceptional effective dopant to promote the precipitation of wollastonite crystal. Finally, ZrO2 containing glass-ceramics was chosen to study the influence of sintering temperature and soaking time with the help of X-ray diffraction analysis and density measurement. The glass-ceramics can be well consolidated at 850 ℃ for 10 min, with low dielectric constant （5.87） and loss （3.21×10^-4）, which is desirable for LTCC application.展开更多
基金supported by the National Natural Science Foundation of China(21377018)the Natural Science Foundation of Liaoning Province of China(2013020116)the Fundamental Research Funds for the Central Universities(DUT15ZD240)~~
文摘A ternary composite of TiO2 and a SiO2-Al2O3 aerogel with good photocatalytic activity was prepared by a simple sol-gel method with TiO2 nanoparticles and SiO2-Al2O3 aerogels derived from industrial fly ash.The structural features of the TiO2/SiO2-Al2O3 aerogel composite were investigated by X-ray powder diffraction,Fourier transform infrared spectroscopy,transmission electron microscopy,gas adsorption measurements and diffuse reflectance UV-visible spectroscopy.The optimal conditions for photocatalytic degradation of 2-sec-butyl-4,6-dinitrophenol（DNBP],included an initial DNBP concentration of 0.167 mmol/L at pH = 4.86 with a catalyst concentration of 6 g/L,under visible light irradiation for 5 h.A plausible mechanism is proposed for the photocatalytic degradation of DNBP.Our composite showed higher photocatalytic activity for DNBP degradation than that of pure TiO2.This indicates that this material can serve as an efficient photocatalyst for degradation of hazardous organic pollutants in wastewater.
基金Projects(51264023,51364020,U1202271)supported by the National Natural Science Foundation of ChinaProject(IRT1250)supported by the Program for Innovative Research Team in University of Ministry of Education of ChinaProject(2014HA003)supported by the Science and Technology Leading Talent of Yunnan Province,China
文摘The crystallization behavior and kinetics of CaO-MgO-Al2O3 SiO2（CMAS） glass with the Fe2O3 content ranging from zero to 5%were investigated by differential scanning calorimetry（DSC）.The structure and phase analyses were made by Fourier transform infrared spectroscopy（FT-IR） and X-ray diffraction（XRD）.The experiment results show that the endothermic peak temperature about 760℃ is associated with transition and the exothermic peak temperature about 1000℃ is associated with crystallization.The crystallization peak temperature decreases with increasing the Fe203 content.The crystallization mechanism is changed from two-dimensional crystallization to one-dimensional growth,and the intensity of diopside peaks becomes stronger gradually.There is a saltation for the crystallization temperature with the addition of 0.5%Fe2O3 due to the decomposition of Fe2O3.Si-O-Si,O-Si-O and T-O-T（T=Si,Fe,Al） linkages are observed in Fe2O3-CaO-MgO-Al2O3-SiO2 glass.
基金Project(2007AA03Z0455) supported by the National High Technology Research and Development Program of ChinaProject(BE2010194) supported by Science&Technology Pillar Program of Jiangsu Province, China+1 种基金Project(KF201103) supported by the State Key Laboratory of New Ceramic and Fine Processing, Tsinghua University, ChinaProject supported by the Priority Academic Development of Jiangsu Higher Education Institutions, China
文摘CaO-B203-SiO2 （CBS） glass powders are prepared by conventional glass melting method at different melting temperatures whose properties and microstructures are characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It is found that there are SiO2 and some unknown phases in CBS glass melting liquid from 1 300 ℃ to 1 500 ℃ and the amount of these phases decreases with the increase of the melting temperature. The CBS glass melted at 1 450 ℃ could be sintered from 830 ℃ to 930 ℃ and the bulk densities of the samples are all higher than 2.4 g/cm^3. From the points of the properties and energy conservation, the melting temperature of 1 450 ℃ is the optimal melting temperature. The glass ceramic sintered at 850 ℃ exhibits better dielectric properties： er=6.33, tan6=2.2×10^-3 at 10 GHz, and the major phases of the samples are CaSiO3, CaB2O4 and SiO2.
基金Item Sponsored by National Natural Science Foundation of China(51174054,51104041,51374065)
文摘The sintering characteristics at 1350℃ and leaching property at 80℃ of calcium aluminate clinkers in the CaO-Al2O3-SiO2 （C-A-S） system with different additions of FeO and Fe2O3 were investigated. FeO inhibits the conversion of β-Ca2SiO4 to γ-Ca2SiO4 and makes the clinker not pulverizable. FeO and Fe2O3 inhibit the formation of CaAl2O4, but promote the formation of Ca12Al14O33. The interplanar spacing at （2 1 1） crystal face of Ca12 Al14O33 in the clinker increases with the increase of FeO addition, which indicates that FeO forms solid solutions in Ca12Al14O33. The clinkers with Fe2O3 addition form a new phase Ca2Fe2O5, and the amount of Ca2Fe2o5 increases with the in crease of Fe2O3 addition. Both FeO and Fe2O3 do not affect the Al2O3 leaching rate of calcium aluminate clinker in sodium carbonate solution, but they increase the molar ratio of caustic Na2O to Al2O3 in the leached liquor.
基金supported by the Education Department of Zhejiang Province (20050359)
文摘A near infrared to visible blue, green, and red upconversion luminescence in a Tb^3＋-doped CaO-Al2O3-SiO2 glass was studied, which was excited using 800 nm femtosecond laser irradiation. The upconversion luminescence was attributed to ^5D3→^7F5, ^5D3→^7F4, ^5D3→^7F3, ^5D4→^7F6, ^5D4→^7F5, ^5D4→^7F4, and ^5D4→^7F3 transitions of Tb^3＋. The relationship between upconversion luminescence intensity and the pump power indicated that a three-photon simultaneous absorption process was dominant in this upconversion luminescence. The intense red, green, and blue upconversion luminescence of Tb^3＋-doped CaO-Al2O3-SiO2 glass may be potentially useful in developing three-dimensional display applications.
基金Financial support from the National Natural Science Foundation of China (21163019) is gratefully acknowledged
文摘Ni/Al_2O_3-SiO_2 catalysts were synthesized via one-step method employing SiO_2 as an additive for the selective hydrogenation of butyne-1,4-diol(B_3D) to butane-1,4-diol(B1D). The prepared catalysts were evaluated by a series of characterization techniques including BET, XRD, SEM, EDX-mapping, TEM, H_2-TPR, XPS, NH_3-TPD and Py-FTIR. Compared to Ni/Al_2O_3 catalyst, the SiO_2-doped samples exhibited better B_3D conversion. SiO_2 could help to form a strong interaction between NiO with the support, which inhibited Ni agglomeration at high temperature, improved the Ni dispersion, and enhanced the hydrogenation activity. B_1D selectivity was mainly influenced by the quantity of Lewis acid sites in addition to the Ni dispersion. The catalyst with a silica loading of 6.4% demonstrated an excellent selectivity of 75.18%(by 13% higher than the contrastive Ni/Al_2O_3 catalyst), which was attributed to the larger amount of Lewis acid sites and the moderate interaction between NiO with the support, which could facilitate the nickel dispersion on a preferable surface area of 176.3 m^2/g of support.
基金Funded by the Shanghai Leading Academic Discipline Project (B502)Shanghai Key Laboratory Project (08DZ2230500)
文摘ZrO2, TiO2 and P2O5 were doped in CaO-B2O3-SiO2 glass-ceramics as nucleating additives. Effects of different nucleating additives on the phase separation and crystalline behaviors were investigated by using gradient temperature furnace, DTA and XRD. Then, sintering process of the glass-ceramics was investigated by testing sintering shrinkage, dielectric constant and loss. The experimental results shows that the glass-ceramics doped with nucleating additives represents higher crystallization, with ZrO2 as an exceptional effective dopant to promote the precipitation of wollastonite crystal. Finally, ZrO2 containing glass-ceramics was chosen to study the influence of sintering temperature and soaking time with the help of X-ray diffraction analysis and density measurement. The glass-ceramics can be well consolidated at 850 ℃ for 10 min, with low dielectric constant （5.87） and loss （3.21×10^-4）, which is desirable for LTCC application.
