超临界CO_2流体浸渍制备D-葡萄糖加氢钌碳催化剂的研究

以氯化钌为活性前驱体,椰壳活性碳为载体,SCCO2流体为浸渍介质制备了负载Ru/AC催化剂,采用正交试验对SCCO2流体浸渍的主要工艺参数对制备Ru/AC D-葡萄糖加氢催化剂的活性影响规律进行了考察,并用H2-TPR、H2-TPD、ICP、TEM等手段对催化剂样品的结构进行了表征.试验结果表明:SCCO2流体介质浸渍法是一种有效的制备负载型Ru/AC催化剂的新方法,SCCO2各参数对制备催化剂活性的影响大小顺序为:温度压力助溶剂量浸渍时间;超临界优化条件下制备催化剂的活性为62.03 mmol·min-1·g-1,是传统水浸渍法制得催化剂的1.55倍.结构表征表明:超临界浸渍有利于活性组分在载体上的均匀分布,提高了活性组分与载体的相互作用,增强了活性组分在载体上的吸附牢固度,有利于催化剂寿命的提高.     

NaBH_4低温还原的负载型镍基催化剂苯酚加氢的研究

采用等体积法分别将3种镍盐Ni(NO3)2、NiCl2、NiSO4浸渍于γ-Al2O3或SiO2,然后用NaBH4低温液相还原制备了负载型金属镍基催化剂,考察了镍源、载体、还原剂用量、反应温度等对负载型镍基催化剂苯酚加氢性能的影响。结果表明,3种镍源中NiCl2的还原程度最高,适于作为NaBH4液相还原体系的催化剂镍源。经NaBH4液相还原的γ-Al2O3负载的镍基催化剂苯酚加氢活性远高于SiO2负载催化剂,加氢产物以环己醇为主。还原剂NaBH4的用量对催化剂的加氢活性具有显著影响,当n(B)/n(Ni)为3时,催化剂的苯酚转化率最高。经过NaBH4还原制备的镍基催化剂耐高温性和稳定性较差,活性组分与载体之间的作用较弱,在高温加氢条件下容易发生团聚而失去活性。     

在Ni-Mo/Al_2O_3上催化裂化轻汽油的选择性加氢

制备了以Al2O3为载体的镍基双金属选择性加氢催化剂,并用于催化裂化轻汽油的选择性加氢反应。考察了载体焙烧温度、金属镍与钼的负载量对催化剂选择性加氢性能的影响。结果表明,适当的焙烧温度降低了催化剂的比表面积和表面酸性,提高了催化剂的稳定性。助剂钼的加入有利于活性组分镍的均匀分散。在反应温度为80℃、空速为10h-1、氢油体积比为10、压力为1.5MPa的工艺条件下,采用Ni-Mo/Al2O3催化剂,催化裂化轻汽油中二烯烃转化率达到98%以上。制备的选择性加氢催化剂具有良好的活性和选择性,可以在选择性加氢领域获得应用。     

炼厂气、CO2和O2制备合成气的实验与分析

利用固定床流动反应装置研究了金属负载型催化剂对炼厂气、CO2 和O2 转化制备合成气的催化活性;考察了催化剂活性组分、载体、负载量、还原温度、反应温度对催化剂活性的影响,发现催化活性由大到小依次为Ni/γ-Al2O3,Ni/α-Al2O3,Co/γ-Al2O3,Fe/γ-Al2O3,Cu/γ-Al2O3;同时考察了空速、原料气配比对合成气组成的影响,结果表明,调节原料气的配比可以制备不同的合成气.     

MoP/TiO_2-SiO_2-Al_2O_3的制备及加氢脱芳性能研究

采用溶胶—凝胶法及共浸渍法制备了TiO2-SiO2-Al2O3复合载体,并用共浸渍法制备负载型MoP/TiO2-SiO2-Al2O3催化剂。XRD结果表明,TiO2的晶相衍射峰呈锐钛矿,SiO2则大多以无定型态分散于γ-Al2O3晶体表面。通过原位还原技术对催化剂进行还原处理,在连续固定床反应器上进行活性评价,结果表明,钛硅铝物质的量比对催化剂的活性有很大的影响,在温度为360℃,压力为3MPa,液时空速为1h-1,氢油体积比为500∶1的反应条件下,n（Ti）∶n（Si）∶n（Al）为1∶1∶4,Mo负载量为20%时,MoP/TiO2-SiO2-Al2O3催化剂的加氢脱芳活性最高,达到65.6%。并且TiO2-SiO2-Al2O3三元复合载体比传统的γ-Al2O3和SiO2-Al2O3二元复合载体的活性分别提高了19.6%和13.6%。     

镍钨系列氮化物催化剂的加氢脱硫催化性能

利用程序升温还原技术,以γ-Al_2O_3为载体,采用浸渍法和混合法制备了一系列不同金属负载量的氮化镍钨加氢精制催化剂NiWN_x/γ-Al_2O_3,在固定床高压微反装置上进行噻吩加氢脱硫实验,考察其加氢脱硫性能。结果表明,不同的制备方法和金属负载量对催化剂催化性能的影响很大。氮化镍钨催化剂(ω(Ni)=2.8％,ω(W)=28％)在反应中表现出优异的催化性能,浸渍法制备的氮化镍钨催化剂比混合法制备的催化剂活性高,氮化镍钨催化剂和氮化态工业催化剂比硫化态工业催化剂的HDS活性高。     

超临界沉积制备葡萄糖加氢钌碳催化剂的研究

以氯化钌为活性前驱体、活性碳为载体,采用CO2超临界沉积技术制备了负载钌/碳催化剂,以葡萄糖催化加氢反应表征了催化剂的活性,研究了助溶剂种类、助溶剂用量、超临界压力对催化剂活性的影响,并用SEM对催化剂表面的形貌及负载钌的分布情况进行了表征.结果表明:CO2超临界沉积技术可有效提高负载钌碳催化剂的活性,在试验范围内,当助溶剂为甲醇、用量为2 mL、超临界CO2压力为12.0 MPa时制得催化剂的活性最佳,其活性是水浸渍方法制得样品的1.48倍.SEM结果表明钌在活性碳表面均匀分布.     

制备条件对Fe/Al2O3选择性催化还原SO2的影响

不同负载量的Fe/Al2O3催化剂分别以浸渍法、共沉淀法和溶胶-凝胶法制得，对比评价了不同方法制备的催化剂样品以CO为还原剂，选择性催化还原SO2的活性。研究表明，铁催化剂有较高的去除SO2的活性，制备方法对催化剂活性具有显著影响。其中溶胶-凝胶法和共沉淀法最高活性分别可以达到95%和85%左右；而浸渍法样品的活性较差，最高转化率不到60%。3种不同组分催化剂的活性在低温时并不明显，在高温时明显地显示出高的负载量具有高的活性。     

MoP/TiO2-SiO2-Al2O3的制备及加氢脱芳性能研究

采用溶胶-凝胶法及共浸渍法制备了TiO2-SiO2-Al2O3复合载体,并用共浸渍法制备负载型MoP/TiO2-SiO2-Al2O3催化剂.XRD结果表明,TiO2的晶相衍射峰呈锐钛矿,SiO2则大多以无定型态分散于γ-Al2O3晶体表面.通过原位还原技术对催化剂进行还原处理,在连续固定床反应器上进行活性评价,结果表明,钛硅铝物质的量比对催化荆的活性有很大的影响,在温度为360℃,压力为3 MPa,液时空速为1 h-1,氢油体积比为500:1的反应务件下,n(Ti):n(Si):n(Al)为1: 1:4,Mo负载量为20%时,MoP/TiO2-SiO2-Al2O3催化剂的加氢脱芳活性最高,达到65.6%.并且TiO2-SiO2-Al2O3三元复合载体比传统的γ-Al2O3和SiO2-Al2O3二元复合载体的活性分别提高了19.6%和13.6%.     

载体酸碱性对镍基催化剂催化甘油水蒸汽重整制氢影响

采用等体积浸渍法制备了以Al2O3,SiO2,ZnO,MgO,白云石(CaMg[CO3]2)等具有不同酸碱性质氧化物作为载体的负载型镍基催化剂.在固定床反应装置中考察了上述催化剂的甘油水蒸汽重整制氢的催化性能.结果表明:在常压、反应温度350～500℃条件下,载体酸碱性对镍基催化剂甘油水蒸汽重整制氢的催化性能影响很大.相比负载于酸性氧化物载体的镍基催化剂(Ni/Al2O3,Ni/SiO2),负载于碱性氧化物载体的镍基催化剂(Ni/白云石,Ni/MgO)能够获得更高的甘油转化率以及氢气选择性,在450℃时甘油转化率与氢气选择性可分别达到100％和84％.这表明以碱性氧化物作为负载镍催化剂载体时,镍基催化剂对甘油水蒸汽催化重整制氢反应有较好的催化性能.     

SnO2及SnO2／Fe2O3复合微米材料的合成及表征

本文首先以SnCl2·2H2O为主要原料,无水乙醇为溶剂,利用溶剂热法于180℃反应24h得到了SnO2微球;再以所制备的SnO2微球为前驱体,FeCl3·6H2O为主要原料,通过水热法得到SnO2／Fe2O3复合材料．利用X射线粉末衍射仪（XRD）和扫描电子显微镜（SEM）对所得产物进行了表征．结果表明：所得的SnO2为四方锡石型,形貌为微球,平均直径约为2．0μm;复合后得到的SnO2／Fe2O3微球平均直径约为2．5μm．其中,Fe2O3为六方赤铁矿型,在复合物的表面以小颗粒的形式存在,尺寸约为200nm．另外,也对SnO3与SnO2／Fe2O3微球的形成过程进行了讨论．     

Temperature dependence on reaction of CaCO3 and SO2 in O2/CO2 coal combustion

The temperature dependence on the reaction of desulfurization reagent CaCO₃ and SO₂ in O₂/CO₂ coal combustion was investigated by thermogravimetric analysis, X-ray diffraction measurement and pore structure analysis. The results show that the conversion of the reaction of CaCO₃ and SO₂ in air is higher at 500–1 100 °C and lower at 1 200 °C compared with that in O₂/CO₂ atmosphere. The conversion can be increased by increasing the concentration of SO₂, which causes the inhibition of CaSO₄ decomposition and shifting of the reaction equilibrium toward the products. XRD analysis of the product shows that the reaction mechanism of CaCO₃ and SO₂ differs with temperature in O₂/CO₂ atmosphere, i.e. CaCO₃ directly reacts with SO₂ at 500 °C and CaO from CaCO₃ decomposition reacts with SO₂ at 1 000 °C. The pore analysis of the products indicates that the maximum specific surface area of the products accounts for the highest conversion at 1 100 °C in O₂/CO₂ atmosphere. The results reveal that the effect of the atmosphere on the conversion is temperature dependence.     

Preparation of TiO2 photocatalyst loaded with V2O5 for O2 evolution

TiO₂ photocatalysts loaded with V₂O₅ were prepared via a modified hydrolysis process, and characterized by X-ray diffraction, transmission electron microscopy, Raman spectra and diffuse reflectance UV-Vis spectra measurements. The photocatalytic activity of V₂O₅/TiO₂ was investigated by employing splitting of water for O₂ evolution. The results indicate that V₂O₅ loading can pronouncedly improve the photocatalytic activity of TiO₂ with Fe³⁺ as an electron acceptor under UV or visible light irradiation. The optimum mass fraction of the loaded V₂O₅ is 8%, and the largest speed of O₂ evolution for 8%V₂O₅ (mass fraction) loaded TiO₂ catalyst is 118.2 μmol/(L·h) under UV irradiation, and 83.7 μmol/(L·h) under visible light irradiation.     

三氧化二铝是导致建筑物火灾的严重隐患

建筑物供电线路中的铜线与铝线连接处常常生成一种灰白物质－－三氧化二铝,极易引发建筑物火灾。着重介绍和分析这种灰白物质的成分、生成原因、危害以及防止其生成的主要措施。     

Modification of nano-TiO2 by Al2O3 in-situ coating

A novel technology of in-situ coating Al₂O₃ on the surface of H₄TiO₄ was developed to prevent the aggregation of nano-TiO₂ powders and improve the dispersibility and thermal stability in the way of forming a uniform coating layer. The heterogeneous nucleation was conducted to prepare the precursor of nano-TiO₂ and then Al₂O₃ was coated on the surface of precursor. The effects of Al₂O₃ in-situ coating on the properties of nano-TiO₂ were investigated. The results show that H₄TiO₄ can be dispersed well under alkaline condition (pH 8.5) and the heterogeneous nucleation can be controlled easily. The optimized uniform coating layer is obtained by adding 5% (mass fraction) and 10% of Al₂O₃ and the aggregation of nano-TiO₂ powders is effectively inhibited and the dispersibility is obviously improved. The crystal sizes of TiO₂ powders are 12.3, 11.4 and 8.7 nm after coating 0,5% and 10% of Al₂O₃ respectively. Al₂O₃ on the surface of particulates in amorphous phase could increase the thermal stability of nano-particles after calcined at 550 °C. Foundation item: Project(04GK2007) supported by Hunan Industrial Key Project of Science and Technology     

氢（氘、氚）分子与低能氦原子（E=0.1eV）碰撞研究

对H2,D2,T2碰撞体系,采用Tang-Toennies势,用密耦方法求解散射方程,计算了E＝0.1eV时00－00,00－02,00－04分子转动激发分截面和角分布,并研究了原子与分子碰撞弹性分波截面和非弹性激发截面随量子数增加的变化规律。     

Bi2O3和Fe2O3掺杂对BaTiO3陶瓷显微结构的影响

利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线能量色散谱(EDAX)等结构分析技术,研究了施主(Bi     

负载型催化剂MnOx-CeO2/TiO2去除甲苯

为了考察铈掺杂对金属氧化物催化剂催化燃烧处理有机废气的影响,采用蜂窝状TiO2丝网作为催化燃烧催化剂的载体,以MnOx、CeO2作为活性组分,用浸渍法负载制备出催化燃烧催化剂,考察了活性组分负载量及配比、焙烧温度、焙烧时间对催化剂降解甲苯的影响.实验确定了催化剂的最佳制备工艺:Mn的负载量(质量分数)约为15%,Mn与Ce物质的量比为3∶1,催化剂的焙烧温度为500℃,焙烧时间为5h.结果表明:与催化剂MnOx/TiO2相比,掺杂Ce后的催化剂MnOx-CeO2/TiO2对甲苯催化燃烧的起燃温度和完全转化温度均有明显降低,催化剂表面燃烧物颗粒的粒径有所减小,分散均匀,更有利于甲苯的降解处理.     

氧化铝增强的PdSe2/Si异质结光电探测器

为了降低暗电流,通过原子层沉积(ALD)生长了一层氧化铝(Al₂O₃)隧穿层,制备了PdSe₂/Al₂O₃/Si异质结光电探测器.通过优化Al₂O₃层的厚度,使得该探测器实现了高速和宽光谱响应.研究结果表明,在波长为808 nm的光照射和-2 V偏压下,所制备的光电探测器与未生长Al₂O₃的器件相比,暗电流降低了约3个数量级,器件的光响应度达到了约为0.31 A/W,对应的比探测率约为2.5×10¹² Jones,器件在零偏压下表现出明显的自驱动效应.经过循环测试1 200次后,器件保持良好的光响应.器件响应的上升时间和下降时间分别为7.1和15.6μs.结果表明,在二维层状半导体材料与Si之间引入Al₂O₃隧穿层,可以有效地降低器件的暗电流,有利于高性能的Si基光电探测器的制备.     

Characteristics of LiCoO2, LiMn2O4 and LiNi0.45Co0.1Mn0.45O2 as cathodes of lithium ion batteries

LiNi_0.45Co_0.10Mn_0.45O₂ was synthesized from Li₂CO₃ and a triple oxide of nickel, cobalt and manganese at 950 °C in air. The structures and characteristics of LiNi_0.45Co_0.10Mn_0.45O₂, LiCoO₂ and LiMn₂O₄ were investigated by XRD, SEM and electrochemical measurements. The results show that LiNi_0.45Co_0.10Mn_0.45O₂ has a layered structure with hexagonal lattice. The commercial LiCoO₂ has sphere-like appearance and smooth surfaces, while the LiMn₂O₄ and LiNi_0.45Co_0.10Mn_0.45O₂ consist of cornered and uneven particles. LiNi_0.45Co_0.10Mn_0.45O₂ has a large discharge capacity of 140.9 mA · h/g in practical lithium ion battery, which is 33.4% and 2.8% above that of LiMn₂O₄ and LiCoO₂, respectively. LiCoO₂ and LiMn₂O₄ have higher discharge voltage and better rate-capability than LiNi_0.45Co_0.10Mn_0.45O₂. All the three cathodes have excellent cycling performance with capacity retention of above 89.3% at the 250th cycle. Batteries with LiMn₂O₄ or LiNi_0.45Co_0.10Mn_0.45O₂ cathodes show better safety performance under abusive conditions than those with LiCoO₂ cathodes. Foundation item: Project(50302016) supported by the National Natural Science Foundation of China; Project(2005037698) supported by the Postdoctoral Science Foundation of China