The performance of BaC12-TiO2-SnO2 composite catalysts in oxidative coupling of methane reaction has been investigated. A series of BaC12-TiO2, BaC1E-SnO2, TiO2-SnO2, and BaC12-TiO2-SnO2 catalysts were prepared, and c...The performance of BaC12-TiO2-SnO2 composite catalysts in oxidative coupling of methane reaction has been investigated. A series of BaC12-TiO2, BaC1E-SnO2, TiO2-SnO2, and BaC12-TiO2-SnO2 catalysts were prepared, and characterized by BET, XRD, XPS, CO2-TPD and H2-TPR, respectively. The synergistic effect among BaC12, SnO2 and TiO2 compositions enhances the catalytic performance. The best C2 selectivity and ethylene yield are obtained on the catalyst with the equal molar amount of the three compositions （BaC12 ： TiO2 ： SnO2 molar ratio of 1 ： 1 ： 1）. The optimal reaction conditions are as follows： 800 ℃, 44 mL.min-1 for methane, 22 mL.min-1 for oxygen and a space velocity of 5000 mL-h-1 .g-1, and the C2H4 yield over the catalyst is 20.1% with the CH4 conversion of 43.8% and C2 selectivity of 53.3%.展开更多
A lithium ion conductive solid electrolyte, L20-AI203-TiO2-SiO2-P20s glass with NASICON- type structure have been synthesized and transformed into glass-ceramic through thermal-treatment at various temperatures from 7...A lithium ion conductive solid electrolyte, L20-AI203-TiO2-SiO2-P20s glass with NASICON- type structure have been synthesized and transformed into glass-ceramic through thermal-treatment at various temperatures from 700 to 1 000 ~C for 12 h. The differential scanning calorimetry （DSC）, X-ray diffraction （XRD）, scanning electron microscopy （SEM） and complex impedance techniques were employed to characterize the samples. The experimental results indicated that the capability of glass forming in this system is superior to that of L20-A1203-TiO2-PzO~. The glass has an amorphous structure and resultant glass-ceramic mainly consisting of LiTi2（PO4）3 phases. Impurity phases AIPO4, TiO2, TiP207 and unidentified phase were observed. With the enhanced heat-treatment temperature, grain grew gradually and lithium ion conductivity of glass-ceramics increased accordingly, the related impedance semicircles were depressed gradually and even disappeared, which could be analytically explained by the coordinate action of the ＇Constant phase element＇ （CPE） model and the ＇Concept of Mismatch and Relaxation＇ model （CMR）. When the sample is devitrified at 1 000 ~C, the maximum room temperature lithium ion conductivity comes up to 4.1 x 10-4 S/cm, which is suitable for the application as an electrolyte of all-solid-state lithium batteries.展开更多
A series of new microwave dielectric ceramics Ba3-nLa1+nTinNb3-nO12 (n=0,1,2) were prepared in the BaO-La2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics we...A series of new microwave dielectric ceramics Ba3-nLa1+nTinNb3-nO12 (n=0,1,2) were prepared in the BaO-La2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction, scanning electron microscope, and microwave dielectric properties measurements. These samples were identified as single phase and adopted A4B3O12-type cation-deficient hexagonal perovskite structure, which can be described as consisting of identical perovskite-like blocks, three corner-sharing BO6 octahedra thick, separated by layers of vacant octahedral. These ceramics have high dielectric constants in the range of 48-42, high quality factors (Q×f) up to 38 000 GHz, and low temperature coefficient of resonant frequencies (τf) in the range of (-40-+6)×10-6℃-1. With increasing content of La and Ti, the dielectric constants slightly decrease butτf gradually increases.展开更多
文摘The performance of BaC12-TiO2-SnO2 composite catalysts in oxidative coupling of methane reaction has been investigated. A series of BaC12-TiO2, BaC1E-SnO2, TiO2-SnO2, and BaC12-TiO2-SnO2 catalysts were prepared, and characterized by BET, XRD, XPS, CO2-TPD and H2-TPR, respectively. The synergistic effect among BaC12, SnO2 and TiO2 compositions enhances the catalytic performance. The best C2 selectivity and ethylene yield are obtained on the catalyst with the equal molar amount of the three compositions （BaC12 ： TiO2 ： SnO2 molar ratio of 1 ： 1 ： 1）. The optimal reaction conditions are as follows： 800 ℃, 44 mL.min-1 for methane, 22 mL.min-1 for oxygen and a space velocity of 5000 mL-h-1 .g-1, and the C2H4 yield over the catalyst is 20.1% with the CH4 conversion of 43.8% and C2 selectivity of 53.3%.
基金National Basic Research Program of China (No.2009CB939704)National Natural Science Foundation of China (Nos.51032005, 60808024)the Fundamental Research Funds for the Central Universities (Wuhan University of Technology)
文摘A lithium ion conductive solid electrolyte, L20-AI203-TiO2-SiO2-P20s glass with NASICON- type structure have been synthesized and transformed into glass-ceramic through thermal-treatment at various temperatures from 700 to 1 000 ~C for 12 h. The differential scanning calorimetry （DSC）, X-ray diffraction （XRD）, scanning electron microscopy （SEM） and complex impedance techniques were employed to characterize the samples. The experimental results indicated that the capability of glass forming in this system is superior to that of L20-A1203-TiO2-PzO~. The glass has an amorphous structure and resultant glass-ceramic mainly consisting of LiTi2（PO4）3 phases. Impurity phases AIPO4, TiO2, TiP207 and unidentified phase were observed. With the enhanced heat-treatment temperature, grain grew gradually and lithium ion conductivity of glass-ceramics increased accordingly, the related impedance semicircles were depressed gradually and even disappeared, which could be analytically explained by the coordinate action of the ＇Constant phase element＇ （CPE） model and the ＇Concept of Mismatch and Relaxation＇ model （CMR）. When the sample is devitrified at 1 000 ~C, the maximum room temperature lithium ion conductivity comes up to 4.1 x 10-4 S/cm, which is suitable for the application as an electrolyte of all-solid-state lithium batteries.
基金Projects(50572078, 20571059) supported by the National Natural Science Foundation of China
文摘A series of new microwave dielectric ceramics Ba3-nLa1+nTinNb3-nO12 (n=0,1,2) were prepared in the BaO-La2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction, scanning electron microscope, and microwave dielectric properties measurements. These samples were identified as single phase and adopted A4B3O12-type cation-deficient hexagonal perovskite structure, which can be described as consisting of identical perovskite-like blocks, three corner-sharing BO6 octahedra thick, separated by layers of vacant octahedral. These ceramics have high dielectric constants in the range of 48-42, high quality factors (Q×f) up to 38 000 GHz, and low temperature coefficient of resonant frequencies (τf) in the range of (-40-+6)×10-6℃-1. With increasing content of La and Ti, the dielectric constants slightly decrease butτf gradually increases.
