TiO2 supports doped with different amounts of Si were prepared by a sol-gel method, and 1 wt% vanadia （V2O5） loaded on Si-doped TiO2 was obtained by an impregnation method. The mole ratio of Si/Ti was 0.2, NOx conve...TiO2 supports doped with different amounts of Si were prepared by a sol-gel method, and 1 wt% vanadia （V2O5） loaded on Si-doped TiO2 was obtained by an impregnation method. The mole ratio of Si/Ti was 0.2, NOx conversion exceeds 94% at 300℃ and GHSV of 41,324 hr-1 , which is about 20% higher than pure V2O5/TiO2 . The catalysts were characterized by XRD, BET, TEM, FT-IR, NH3-TPD, XPS, H2-TPR, Raman and in situ DRIFTS. The results of FT-IR and XPS indicated that Si was doped into the TiO2 lattice successfully and a solid solution was obtained. V2O5 active component could be dispersed well on the support with the increasing of surface area of the catalyst, which was confirmed by Raman and XRD results. Above all, the numbers of acid sites （especially the Br nsted-acid） and oxidation properties were enhanced for Si-doped V2O5/TiO2 catalysts, which improved the deNOx catalytic activity.展开更多
The VOx catalysts supported on dealuminated Beta zeolite(Si Beta) with varying V loadings(from 0.5 to 10 wt%) are prepared and tested for their catalytic activities in the reaction of direct dehydrogenation of propane...The VOx catalysts supported on dealuminated Beta zeolite(Si Beta) with varying V loadings(from 0.5 to 10 wt%) are prepared and tested for their catalytic activities in the reaction of direct dehydrogenation of propane to propylene(PDH). It is characterized that the VSi Beta catalysts possess different kinds of vanadium species on the Si Beta support, including monomeric or isolated VOx species at a low V loading, and polynuclear VOx species in different polymerization degrees at higher V loadings. The 3 VSi Beta catalyst(V loading is 3 wt%), containing isolated VOx species in monolayer, shows around 40% of propane conversion with 90% of propylene selectivity(reaction conditions: 600 o C, 4000 m L g–1 h–1) which are comparable to VSi Beta catalysts with higher V loadings. The catalytic activity exhibits a good linear relationship with the amount of generated acidic sites, which are derived from the interaction sites between VOx species and Si Beta support, and keeps stable after several regeneration cycles. Thus, as the VOx species directly contact with Si Beta support via V–O–Si bonds, a reactivity enhancement can be achieved. While, the initial valence state of V does not seem to influence the catalytic performance. Moreover, the aggregation degree of VOx species determines the propylene selectivity and deactivation rate, both of which increase as raising the V loading amount.展开更多
VOx/SiO2 catalysts prepared by impregnation method were used for catalytic dehydrogenation of n-butane to butenes and characterized by X-ray diffraction, FT-IR, UV-vis, Raman, and BET measurements. The effects of VOx ...VOx/SiO2 catalysts prepared by impregnation method were used for catalytic dehydrogenation of n-butane to butenes and characterized by X-ray diffraction, FT-IR, UV-vis, Raman, and BET measurements. The effects of VOx loading and the reaction temperature on the VOx/SiO2 catalysts and their catalytic performances for the dehydrogenation of n-butane were studied. When the VOx loading was 12% g/gcat and reaction temperature was between 590 ℃ and 600℃, n-butane conversion and butenes yields reached the highest value under H2 flux of 10 ml/min and n-butane flux of 10 ml/min. Product distribution, such as the ratio of 2-butene to 1-butene and the ratio of cis-2-butene to trans-2-butene, was mainly influenced by the reaction temperature.展开更多
研制出一款640×512高性能17μm非制冷氧化钒红外焦平面探测器。读出电路输入级采用镜像电路获得盲像元(Rd)和感光像元(Rs)电流差的积分电流(Iint),并能够有效抑制输入偏压噪声;同时采用逐行积分、逐列读出模式。氧化钒采用单层微...研制出一款640×512高性能17μm非制冷氧化钒红外焦平面探测器。读出电路输入级采用镜像电路获得盲像元(Rd)和感光像元(Rs)电流差的积分电流(Iint),并能够有效抑制输入偏压噪声;同时采用逐行积分、逐列读出模式。氧化钒采用单层微桥工艺;像元桥臂间距缩至0.8mm,以尽可能增大桥面及VO_x面积,有效提高像元响应率。器件采用高可靠性的金属真空封装。测试结果表明,器件的噪声等效温差(NETD)小于45 m K,响应率大于15 m V/K,热响应时间小于10 ms。展开更多
We demonstrate the polarization of resistive switching for a Cu/VOx/Cu memory cell.The switching behaviors of Cu/VOx/Cu cell are tested by using a semiconductor device analyzer（Agilent B1500A）,and the relative micro...We demonstrate the polarization of resistive switching for a Cu/VOx/Cu memory cell.The switching behaviors of Cu/VOx/Cu cell are tested by using a semiconductor device analyzer（Agilent B1500A）,and the relative micro-analysis of I-V characteristics of VOx/Cu is characterized by using a conductive atomic force microscope（CAFM）.The I-V test results indicate that both the forming and the reversible resistive switching between low resistance state（LRS） and high resistance state（HRS） can be observed under either positive or negative sweep.The CAFM images for LRS and HRS directly exhibit evidence for the formation and rupture of filaments based on positive or negative voltage.The Cu/VOx/Cu sandwiched structure exhibits reversible resistive switching behavior and shows potential applications in the next generation of nonvolatile memory.展开更多
基金supported by the National Natural Science Foundation of China (No. 51078185, U1162119)the research fund of Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province (No. AE201001)the research fund for the Doctoral Program of Higher Education of China (No.20113219110009)
文摘TiO2 supports doped with different amounts of Si were prepared by a sol-gel method, and 1 wt% vanadia （V2O5） loaded on Si-doped TiO2 was obtained by an impregnation method. The mole ratio of Si/Ti was 0.2, NOx conversion exceeds 94% at 300℃ and GHSV of 41,324 hr-1 , which is about 20% higher than pure V2O5/TiO2 . The catalysts were characterized by XRD, BET, TEM, FT-IR, NH3-TPD, XPS, H2-TPR, Raman and in situ DRIFTS. The results of FT-IR and XPS indicated that Si was doped into the TiO2 lattice successfully and a solid solution was obtained. V2O5 active component could be dispersed well on the support with the increasing of surface area of the catalyst, which was confirmed by Raman and XRD results. Above all, the numbers of acid sites （especially the Br nsted-acid） and oxidation properties were enhanced for Si-doped V2O5/TiO2 catalysts, which improved the deNOx catalytic activity.
基金supported by the National Natural Science Foundation of China(21421001,21573115)the 111 project(B12015)the Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(2017-K13)~~
文摘The VOx catalysts supported on dealuminated Beta zeolite(Si Beta) with varying V loadings(from 0.5 to 10 wt%) are prepared and tested for their catalytic activities in the reaction of direct dehydrogenation of propane to propylene(PDH). It is characterized that the VSi Beta catalysts possess different kinds of vanadium species on the Si Beta support, including monomeric or isolated VOx species at a low V loading, and polynuclear VOx species in different polymerization degrees at higher V loadings. The 3 VSi Beta catalyst(V loading is 3 wt%), containing isolated VOx species in monolayer, shows around 40% of propane conversion with 90% of propylene selectivity(reaction conditions: 600 o C, 4000 m L g–1 h–1) which are comparable to VSi Beta catalysts with higher V loadings. The catalytic activity exhibits a good linear relationship with the amount of generated acidic sites, which are derived from the interaction sites between VOx species and Si Beta support, and keeps stable after several regeneration cycles. Thus, as the VOx species directly contact with Si Beta support via V–O–Si bonds, a reactivity enhancement can be achieved. While, the initial valence state of V does not seem to influence the catalytic performance. Moreover, the aggregation degree of VOx species determines the propylene selectivity and deactivation rate, both of which increase as raising the V loading amount.
基金The project was supported by Program for New Century Excellent Talents in University (Grant No. NCET-04-0987)Doctor Fund of Science Research of Xinjiang University (Grant No. BS060101).
文摘VOx/SiO2 catalysts prepared by impregnation method were used for catalytic dehydrogenation of n-butane to butenes and characterized by X-ray diffraction, FT-IR, UV-vis, Raman, and BET measurements. The effects of VOx loading and the reaction temperature on the VOx/SiO2 catalysts and their catalytic performances for the dehydrogenation of n-butane were studied. When the VOx loading was 12% g/gcat and reaction temperature was between 590 ℃ and 600℃, n-butane conversion and butenes yields reached the highest value under H2 flux of 10 ml/min and n-butane flux of 10 ml/min. Product distribution, such as the ratio of 2-butene to 1-butene and the ratio of cis-2-butene to trans-2-butene, was mainly influenced by the reaction temperature.
文摘研制出一款640×512高性能17μm非制冷氧化钒红外焦平面探测器。读出电路输入级采用镜像电路获得盲像元(Rd)和感光像元(Rs)电流差的积分电流(Iint),并能够有效抑制输入偏压噪声;同时采用逐行积分、逐列读出模式。氧化钒采用单层微桥工艺;像元桥臂间距缩至0.8mm,以尽可能增大桥面及VO_x面积,有效提高像元响应率。器件采用高可靠性的金属真空封装。测试结果表明,器件的噪声等效温差(NETD)小于45 m K,响应率大于15 m V/K,热响应时间小于10 ms。
基金Project supported by the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-11-1064)the Young Scientists Fund of the National Natural Science Foundation of China (Grant Nos. 61101055,61274113,and 11204212)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20100032120029)Tianjin Natural Science Foundation of China (Grant No. 10SYSYJC27700)
文摘We demonstrate the polarization of resistive switching for a Cu/VOx/Cu memory cell.The switching behaviors of Cu/VOx/Cu cell are tested by using a semiconductor device analyzer（Agilent B1500A）,and the relative micro-analysis of I-V characteristics of VOx/Cu is characterized by using a conductive atomic force microscope（CAFM）.The I-V test results indicate that both the forming and the reversible resistive switching between low resistance state（LRS） and high resistance state（HRS） can be observed under either positive or negative sweep.The CAFM images for LRS and HRS directly exhibit evidence for the formation and rupture of filaments based on positive or negative voltage.The Cu/VOx/Cu sandwiched structure exhibits reversible resistive switching behavior and shows potential applications in the next generation of nonvolatile memory.
