A novel NOx storage/reductiou catalyst 12CaO·7Al2O3/10%K, defined as C12A7/K, was prepared, which possesses good NOx storage/reduction ability with a high sulfur-tolerance. The effect of H2O on the NO reduction f...A novel NOx storage/reductiou catalyst 12CaO·7Al2O3/10%K, defined as C12A7/K, was prepared, which possesses good NOx storage/reduction ability with a high sulfur-tolerance. The effect of H2O on the NO reduction features over the C12A7/K catalyst was investigated, The NO eonversion and the N2 selectivity were measured as a function of temperature and H2O concentration. In the presence of 1.2% H2O, both the NO conversion and the N2 selectivity significantly decrease at lower temperature region （〈500 ℃）. At temperatures over 500℃, however, the NO reduction is only slightly influenced by H2O, The species of NO3^-/NO2^- are confirmed as main storage components in the C12A7/K catalyst, which are thrther reduced into N2 by H2 under the reduction conditions.展开更多
为提升瓦斯抽采利用率、促进煤矿安全生产,采用介质阻挡放电(DBD)试验系统对CH4-O2-N2-H2O反应体系进行低温等离子体转化研究,分析水蒸气与CH4物质的量比、O2/N2物质的量比、放电电压、放电频率,以及气体总流量对CH4转化率及主要产物产...为提升瓦斯抽采利用率、促进煤矿安全生产,采用介质阻挡放电(DBD)试验系统对CH4-O2-N2-H2O反应体系进行低温等离子体转化研究,分析水蒸气与CH4物质的量比、O2/N2物质的量比、放电电压、放电频率,以及气体总流量对CH4转化率及主要产物产率的影响。结果表明:CH4-O2-N2-H2O反应体系DBD的主要产物为H2、CO、CO2、C2H2、C2H4、C2H6和CH3OH;反应参数对CH4转化率和H2、CO、CO2、C2H6、CH3OH产率影响较为显著,而对C2H2、C2H4产率影响不显著;CH4转化率及主要产物产率均在放电频率为9.8 k Hz时取得最大值。展开更多
This review compares the different types of membrane processes for air dehumidification.Three main categories of membrane-based dehumidification are identified–membrane contactors using porous membranes with concentr...This review compares the different types of membrane processes for air dehumidification.Three main categories of membrane-based dehumidification are identified–membrane contactors using porous membranes with concentrated liquid desiccants,separative membranes using dense membrane morphology with a pressure gradient to drive the separation of moisture from air,and adsorptive membranes using nanofibrous membranes which adsorb and capture moisture to realise dehumidification.Drawing upon the importance of dehumidification and humidity control for urban sustainability and energy efficacy,this review critically analyses and recognizes the three unique categories of membrane-based air dehumidification technologies.Essentially,the discussion is broken into three sections-one for each category-discriminating in terms of the driving force,membrane structure and properties,and its performance indicators.Readers will notice that despite having the same objective to dehumidify air,the polymers used amongst each category differs to suit the operating requirements and optimize dehumidification performance.At the end of each section,a performance table or summary of dehumidifying membranes in its class is provided.The final section concludes with a comparative review of the three categories on membrane-based air dehumidification technologies and draw inspiration from parallel research to rationalise the potential and innovative use of promising materials in membrane fabrication for air dehumidification.展开更多
Controlled oxidation experiments were performed on Kovar alloy by changing oxidation atmosphere, temperature, and exposure time to produce films with different oxide type and thickness. The results indicated that sing...Controlled oxidation experiments were performed on Kovar alloy by changing oxidation atmosphere, temperature, and exposure time to produce films with different oxide type and thickness. The results indicated that single Fe3O4 and single FeO were respectively obtained when Kovar alloy was oxidized in N2-2.31%H2O-0.95%H2 at 500℃ and in N2-2.31%H2O-0.5%H2 at 1000℃, and all kinetic curves followed linear relation; mixed oxides of FeO and Fe3O4 formed when Kovar was oxidized in N2-2.31%H2O at 1000℃and parabolic kinetics were obeyed. Analysis of metallographic cross section of oxides indicated that oxygen diffusion inward through the oxide scale is responsible for intergranular oxide, which had formed beneath the oxide scales when the oxide products were mixed oxides of FeO and Fe3O4, and which did not occur when the oxide was single FeO or Fe3O4. The oxidation model was also established.展开更多
煤矿开采逐渐走向深部,深部煤岩体表现为复杂的孔隙结构及低渗透特性,因此正确认识气体与水在煤岩等低渗岩土介质中的渗透规律、表征煤岩孔裂隙结构网络对于深部开采具有重要意义。核磁共振在研究煤岩孔隙结构和渗流路径方面具有快速无...煤矿开采逐渐走向深部,深部煤岩体表现为复杂的孔隙结构及低渗透特性,因此正确认识气体与水在煤岩等低渗岩土介质中的渗透规律、表征煤岩孔裂隙结构网络对于深部开采具有重要意义。核磁共振在研究煤岩孔隙结构和渗流路径方面具有快速无损的特征。为研究深部煤体在氮气驱水与渗流过程中的流体运移和分布,以及深部煤体原始状态与各级围压状态下的煤体内部孔隙的分布情况,对平煤十二矿己15-31030工作面圆柱形煤样试件分别进行了称重、烘干、饱水,在不同驱替压力下对试件进行了氮气驱水与渗流状态下的核磁共振CPMG序列测试和核磁共振(Nuclear Magnetic Resonance,NMR)成像检测,对饱水试样进行了变围压状态下的核磁共振CPMG序列测试。得到了煤样的横向弛豫时间T 2谱、一维频率编码和NMR成像图,并进行了结果分析。分析结果表明,煤体随着围压的增加,其孔隙率并不是单调变化,而是先增加再减小最后趋向于不变,其吸附孔数量变化规律趋近孔隙率的改变;氮气驱水能驱掉运移孔中的水分,对于渗透孔及以下级别孔隙中的总含水量影响不大;通过核磁共振CPMG序列计算得到煤体孔隙率演化图形。NMR成像结果表明,深部煤体大多无散布大孔隙,且小孔隙分布较均匀。展开更多
文摘A novel NOx storage/reductiou catalyst 12CaO·7Al2O3/10%K, defined as C12A7/K, was prepared, which possesses good NOx storage/reduction ability with a high sulfur-tolerance. The effect of H2O on the NO reduction features over the C12A7/K catalyst was investigated, The NO eonversion and the N2 selectivity were measured as a function of temperature and H2O concentration. In the presence of 1.2% H2O, both the NO conversion and the N2 selectivity significantly decrease at lower temperature region （〈500 ℃）. At temperatures over 500℃, however, the NO reduction is only slightly influenced by H2O, The species of NO3^-/NO2^- are confirmed as main storage components in the C12A7/K catalyst, which are thrther reduced into N2 by H2 under the reduction conditions.
文摘为提升瓦斯抽采利用率、促进煤矿安全生产,采用介质阻挡放电(DBD)试验系统对CH4-O2-N2-H2O反应体系进行低温等离子体转化研究,分析水蒸气与CH4物质的量比、O2/N2物质的量比、放电电压、放电频率,以及气体总流量对CH4转化率及主要产物产率的影响。结果表明:CH4-O2-N2-H2O反应体系DBD的主要产物为H2、CO、CO2、C2H2、C2H4、C2H6和CH3OH;反应参数对CH4转化率和H2、CO、CO2、C2H6、CH3OH产率影响较为显著,而对C2H2、C2H4产率影响不显著;CH4转化率及主要产物产率均在放电频率为9.8 k Hz时取得最大值。
基金supported by Singapore Membrane Technology Centre(SMTC),Interdisciplinary Graduate Programme,Nanyang Environment and Water Research institute and Nanyang Technological university for this research.
文摘This review compares the different types of membrane processes for air dehumidification.Three main categories of membrane-based dehumidification are identified–membrane contactors using porous membranes with concentrated liquid desiccants,separative membranes using dense membrane morphology with a pressure gradient to drive the separation of moisture from air,and adsorptive membranes using nanofibrous membranes which adsorb and capture moisture to realise dehumidification.Drawing upon the importance of dehumidification and humidity control for urban sustainability and energy efficacy,this review critically analyses and recognizes the three unique categories of membrane-based air dehumidification technologies.Essentially,the discussion is broken into three sections-one for each category-discriminating in terms of the driving force,membrane structure and properties,and its performance indicators.Readers will notice that despite having the same objective to dehumidify air,the polymers used amongst each category differs to suit the operating requirements and optimize dehumidification performance.At the end of each section,a performance table or summary of dehumidifying membranes in its class is provided.The final section concludes with a comparative review of the three categories on membrane-based air dehumidification technologies and draw inspiration from parallel research to rationalise the potential and innovative use of promising materials in membrane fabrication for air dehumidification.
基金supported by the National Natural Science Foundation of China(No. 50671014).
文摘Controlled oxidation experiments were performed on Kovar alloy by changing oxidation atmosphere, temperature, and exposure time to produce films with different oxide type and thickness. The results indicated that single Fe3O4 and single FeO were respectively obtained when Kovar alloy was oxidized in N2-2.31%H2O-0.95%H2 at 500℃ and in N2-2.31%H2O-0.5%H2 at 1000℃, and all kinetic curves followed linear relation; mixed oxides of FeO and Fe3O4 formed when Kovar was oxidized in N2-2.31%H2O at 1000℃and parabolic kinetics were obeyed. Analysis of metallographic cross section of oxides indicated that oxygen diffusion inward through the oxide scale is responsible for intergranular oxide, which had formed beneath the oxide scales when the oxide products were mixed oxides of FeO and Fe3O4, and which did not occur when the oxide was single FeO or Fe3O4. The oxidation model was also established.
文摘煤矿开采逐渐走向深部,深部煤岩体表现为复杂的孔隙结构及低渗透特性,因此正确认识气体与水在煤岩等低渗岩土介质中的渗透规律、表征煤岩孔裂隙结构网络对于深部开采具有重要意义。核磁共振在研究煤岩孔隙结构和渗流路径方面具有快速无损的特征。为研究深部煤体在氮气驱水与渗流过程中的流体运移和分布,以及深部煤体原始状态与各级围压状态下的煤体内部孔隙的分布情况,对平煤十二矿己15-31030工作面圆柱形煤样试件分别进行了称重、烘干、饱水,在不同驱替压力下对试件进行了氮气驱水与渗流状态下的核磁共振CPMG序列测试和核磁共振(Nuclear Magnetic Resonance,NMR)成像检测,对饱水试样进行了变围压状态下的核磁共振CPMG序列测试。得到了煤样的横向弛豫时间T 2谱、一维频率编码和NMR成像图,并进行了结果分析。分析结果表明,煤体随着围压的增加,其孔隙率并不是单调变化,而是先增加再减小最后趋向于不变,其吸附孔数量变化规律趋近孔隙率的改变;氮气驱水能驱掉运移孔中的水分,对于渗透孔及以下级别孔隙中的总含水量影响不大;通过核磁共振CPMG序列计算得到煤体孔隙率演化图形。NMR成像结果表明,深部煤体大多无散布大孔隙,且小孔隙分布较均匀。
