Establishing TA-Pb/Cu and SA-Pb/Cu interface catalyst shells on HMX surfaces via in situ coprecipitation to ameliorate the performances of HMX

Lead/copper tannate (TA-Pb/Cu) and lead/copper salicylate (SA-Pb/Cu) interface catalyst shells are established on the surface of 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX) via in situ coprecipitation to prepare HMX@TA-Pb/Cu and HMX@SA-Pb/Cu composites. The structures and properties of the obtained HMX@TA-Pb/Cu and HMX@SA-Pb/Cu composites are characterized in detail. Molecular dynamics simulations are performed to study the adsorption mechanism of TA-Pb/Cu and SA-Pb/Cu on HMX surface. The residues after HMX@TA-Pb/Cu and HMX@SA-Pb/Cu combusted in air are collected and characterized to study the catalytic effect of TA-Pb/Cu and SA-Pb/Cu on combustion. The study results show that TA-Pb/Cu shells are coated on HMX surface due to the excellent membrane-forming properties of TA, while SA-Pb/Cu shells are embedded in the gullies and holes of HMX surface. TA-Pb/Cu and SA-Pb/Cu shells can decrease the mechanical sensitivities and catalyze the decomposition and combustion of HMX, and the catalytic effects of in situ coprecipitation are better than that of physical mixing. In addition, the phase transition temperature of HMX in HMX@TA-Pb/Cu is increased while that of HMX@SA-Pb/Cu is decreased, illustrating that TA-Pb/Cu can enhance the thermal stability of HMX while SA-Pb/Cu can catalyze the phase transition of HMX.     

载体表面性质对Cu/ZrO2催化剂CO加氢反应行为的影响

用XRD、LRS、NH₃-TPD、CO₂-TPD和CO-FTIR等表征手段考察了不同温度焙烧的氧化锆表面性质的差别,特别是表面酸碱性的差异对Cu/ZrO₂催化剂CO加氢反应行为的影响。结果表明,不同温度焙烧的氧化锆表面酸碱性具有较大的差异,其中以450℃焙烧的氧化锆具有较高的表面碱性和最低酸性。这些表面性质的差异对于Cu/ZrO₂催化剂的CO吸附行为产生较大的影响,进而影响CO的加氢反应活性。以450℃焙烧的氧化锆为载体时,Cu/ZrO₂催化剂具有较好的反应活性。     

The synthesis of Cu/plate-like ZnO nanostructures and their self-assembly mechanism

A composite Cu/ZnO nanostructure with Cu nanoparticles supported on ZnO hexagonal nanoplates has been successfully fabricated by a heating approach, using their metal oleate salts as the precursors without any additives. Combined Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and other examination technologies, the structural properties and formation mechanism of as-synthesized Cu/ZnO nanocomposites are studied in detail. The results reveal that the nanostructures are plate-like with uniform shape and size, and Cu nanoparticles exhibit specific (111) plane matching with the (002) facet of ZnO, indicating a surface-induced interaction mechanism. Further characterization demonstrates that copper nanoparticles can be generated by a decomposition/self-reduction route of copper salts, and the oleate ions act as dual roles in the process: reducing and protecting agents. The difference of decomposition temperature between metal oleates also plays important roles in the formation of Cu/ZnO nanostructure. In addition, the catalytic performance of these nanocomposites is evaluated and it can be found that compared with Cu/rod-like ZnO, as-synthesized samples are highly selective for methanol.     

Enhanced thermal decomposition,laser ignition and combustion properties of NC/Al/RDX composite fibers fabricated by electrospinning

Cellulose - Nano aluminum (Al) has always been the research hotspot in the field of energetic materials because of its high energy density and combustion temperature, and has been considered to be...     

超临界甲醇中Ce/Cu/Zn/Al催化木质素制备酚类化合物的研究

采用共沉淀法制备Ce/Cu/Zn/Al催化剂,并将其应用于超临界甲醇中木质素的催化液化.考察单因素条件对木质素转化率和生成酚类的影响,得到最佳反应条件:反应温度320℃,反应时间120 min,催化剂用量150 mg,初始压力2 MPa,木质素的转化率达到67.33%,酚类产率达到30.84%.同时,以苯酚及愈创木酚为模型物,比较有无催化剂对液化产物分布或选择性生成的影响. Ce/Cu/Zn/Al催化剂的加入促进了甲醇的重整及其与模型化合物苯酚、愈创木酚的烷基化反应,从而生成了大量的烷基苯酚.     

Cu/SiO2表面性质对甲醇脱氢反应性能的影响

甲醇催化脱氢是将甲醇转化为其它有机化学品的一条有效途径,该反应的产物依反应条件以及催化剂不同有可能是无水甲醛、甲酸甲酯或CO’‘－”．很多研究结果表明铜基催化剂对甲醇脱氢反应表现出较好的催化性能’‘－”,但催化剂的表面结构对其反应性能的影响以及反应过程中由于催化剂结构变化引起的活性和选择性的变化规律还缺乏深入研究．本文以Cll／Sic。为研究对象,考察了制备方法对催化剂甲醇脱氧反应性能的影响．1实验部分1．1催化剂制备负载型催化剂以微球型Sic。作为载体（BET比表面积3635mZ·g－‘）,分别以钢氨溶液和硝酸铜…     

Cu/Zn、Cu/Zn/Ni催化剂甲醇部分氧化制氢

研究了甲醇在Cu/Zn及Cu/Zn/Ni催化剂上部分氧化热耦合裂解制氢的反应,系 统地考察了不同O2/CH3OH比及反应温度下催化剂性能.当O2/CH3OH=0.2时,催化剂的性能最 佳.在同样条件下, Cu/Zn催化剂对CO的选择性较Cu/Zn/Ni催化剂低,更具优势. Cu/Zn催化 剂用于甲醇部分氧化反应时,甲醇转化率在150 h寿命实验中基本保持在90％左右. XRD谱图 表明Cu/Zn合金的生成是导致Cu/Zn系催化剂在甲醇裂解反应中快速失活的主要原因,而在部 分氧化反应中, O2的存在可抑制Cu/Zn合金的生成,使Cu/Zn催化剂表现出高度的稳定性.     

Kinetics of no decomposition over Cu/ZSM-5 catalyst

The kinetics of catalytic decomposition of NO over Cu/ZSM-5 catalyst has been studied in an integral flow reactor at atmospheric pressure. Kinetic analysis is based on the assumption that the surface reaction represents the rate-determining step. On the basis of theoretical considerations of different interactions between reactants and catalyst, and experimental evidences, three different mechanistic kinetic models were chosen. Also a power-law model was tested. The best agreement has been achieved with the model

新型高性能Cu/HMS催化剂的合成及其在草酸二甲酯催化加氢合成 乙二醇反应中的应用

采用原位合成法合成了介孔Cu/HMS催化剂, 并以草酸二甲酯催化加氢合成乙二醇为探针反应考察了不同焙烧温度对反应催化性能的影响, 结果表明焙烧温度为650 ℃时合成的催化剂在该反应中表现出最佳的催化性能. 在反应温度为200 ℃、压力为3 MPa、氢酯比为50、液时空速为0.74 h－1的条件下, 草酸二甲酯的转化率达到100%, 并且乙二醇的选择性达到97%. 采用X射线粉末衍射、N2低温吸附、H2-TPR、N2O滴定、X射线光电子能谱及傅利叶变换红外光谱对系列催化剂进行了系统表征, 阐述了焙烧温度对催化性能影响的本质原因. 研究表明焙烧温度能够影响活性铜物种的分散度和铜物种与载体间的相互作用, 从而影响草酸二甲酯催化加氢的催化性能.     

[NiFe/Cu/Co/Cu]n纳米多层线的电化学制备及表征

采用电沉积法,在阳极氧化铝(AAO)模板中制备了[NiFe/Cu/Co/Cu]_n多层纳米线.利用扫描电子显微镜(SEM)及透射电子显微镜(TEM)对纳米多层线的表面形貌及结构进行了表征,纳米线阵列高度有序、直径均一、层状结构清晰,NiFe层厚度约40 nm,Cu层厚度约60 nm,Co层厚度约15 nm,各子层厚度可控.利用X射线能谱分析仪(EDS)对纳米多层线NiFe层的成分进行了测试,Ni,Fe的原子比为4:1.利用X射线衍射仪(XRD)对[NiFe/Cu/Co/Cu]_n纳米多层膜和多层线结构进行了测试,多层膜为面心立方(fcc)结构,多层线NiFe层为面心立方(fcc)结构,Cu层为六方密排hcp(100),Co层为面心立方(fcc)结构.与组成、结构完全相同的多层膜相比,[NiFe/Cu/Co/Cu]_n多层纳米线具有更优越的巨磁电阻性能.     

微波热解法制备Cu/Cu2O纳米材料

在二乙二醇溶剂体系中利用微波介电加热分解醋酸铜前体,进一步还原得到Cu2O和Cu纳米粒子以及Cu/Cu2O核壳结构。 采用X射线衍射、透射电子显微镜、扫描电子显微镜和紫外吸收光谱测试技术对产物的形貌、结构和组成进行了研究,结果表明,得到的Cu/Cu2O核壳结构直径为500 nm左右。 对比实验研究了不同聚合度乙二醇系列溶剂、反应时间以及表面活性剂或配位剂对产物形貌、组成的影响,表明低聚合度乙二醇和长的反应时间有利于醋酸铜还原形成铜。     

花状Cu2O/Cu的水热合成及其光催化性能

以硝酸铜为前驱体, 不采用任何模板, 通过逐步水热法合成了花状Cu2O/Cu复合纳米材料. 用扫描电镜(SEM)、X射线衍射(XRD)和紫外-可见漫反射光谱(DRS)对样品进行表征. 结果表明, 花状纳米Cu2O/Cu材料是由长为300-500 nm, 宽为30-70 nm的带状花瓣构成, 在可见光区域有很强的吸收. 复合材料中Cu的含量可以通过反应时间进行调控. 对染料Procion Red MX-5B(PR)的可见光催化降解, Cu能明显提高Cu2O的光催化性能. 当Cu质量分数为27%-71%时, 复合材料Cu2O/Cu的催化活性明显高于单相Cu2O. 与立方体形貌的Cu2O/Cu复合材料相比, 花状纳米Cu2O/Cu复合材料对染料PR有更高的催化降解性能. 且该复合材料有较高的循环回收利用率.     

ZrO2修饰Cu催化剂对甲醇吸附原位红外表征

通过原位红外漫反射实验比较研究了甲醇在Cu及ZrO2/Cu催化剂表面的吸附与反应,并且采用不同还原温度来处理催化剂,改变催化剂表面的氧含量,并进一步研究甲醇吸附和反应性能随着催化剂表面氧含量的变化规律.结果表明,甲醇在Cu催化剂表面反应生成吸附态甲醛物种,进一步生成CO2,而在ZrO2/Cu表面形成甲酸盐物种,并与表面氧进一步反应生成CO2.随着催化剂还原温度的升高,反应中间物进一步生成CO2的反应速率变慢,说明催化剂表面的氧物种含量决定着催化剂甲醇吸附中间物种的形成及反应速率.     

Effects of ethanol on the in situ synthesized Cu/SiO_2 catalyst:Texture,structure,and the catalytic performance in hydrogenation dimethyl oxalate to ethylene glycol

The Cu/SiO₂ catalysts were in situ synthesized by the hydrolysis of tetraethyl orthosilicate（TEOS） in one phase solution using ethanol as co-solvent or TEOS/H₂O two phases solution,followed by the precipitation of copper on SiO₂ by ammonia evaporation. In the hydrogenation of dimethyl oxalate,the catalyst prepared by one phase hydrolysis exhibited higher activity and ethylene glycol（EG） selectivity at lower temperature than that of two phases due to its larger BET surface area and multimodal pore distribution.At 488-503 K,the catalyst prepared in one phase solution with water/ethanol（W/E） volume ratio of 3:1 exhibited 90- 95%EG selectivity,while catalyst prepared by two phase hydrolysis reached 90%EG selectivity only at 498-503 K.     

Cu-M/ZSM-S(M=Ce,La,Ag)催化剂的表征及其对NO直接分解催化活性的研究

考察了用分散法制备的Ｃｕ－Ｍ／ＺＳＭ－５（Ｍ＝Ｃｅ,Ｌａ,Ａｇ）催化剂对ＮＯ直接分解的催化活性,并且用ＸＲＤ、ＳＥＭ、ＴＰＲ、ＸＰＳ及ＩＣＡＰ等手段对催化剂进行了表征。结果表明添加Ｃｅ有利于增加催化剂的铜离子交换度,添加Ａｇ有可能使ＺＳＭ－５分子筛的骨架结构发生改变,从而对催化剂活性产生影响。     

热处理对[NiFe/Cu/Co/Cu]_n多层纳米线磁性能的影响

采用双槽控电位法在阳极氧化铝(AAO)模板中制备了有序均一的[NiFe/Cu/Co/Cu]n多层纳米线阵列,并在不同温度下进行了热处理.利用X射线衍射(XRD)对热处理前后多层线的晶体结构进行了测试.考察了不同退火温度对多层线矫顽力、剩磁比、巨磁电阻(GMR)效应、磁灵敏度的影响.随热处理温度升高,多层纳米线中磁性微晶晶型取向越来越明显,晶体结构更均匀;多层纳米线的矫顽力和剩磁比先增大后减小.300°C下多层纳米线矫顽力达到最大值,GMR最大值可达59%,对应的磁电阻灵敏度(SV)为0.233%Oe-1.     

Cu/Zn比对微波辐射老化制备CuO/ZnO/Al2O3催化剂结构和活性的影响

在微波辐射条件下, 对共沉淀法制备合成甲醇CuO/ZnO/Al₂O₃催化剂前驱体的母液进行老化, 通过改变Cu/Zn比, 研究了微波辐射对催化剂性能的影响, 并结合XRD, FTIR, DTG, H₂-TPR, XPS等表征手段, 探讨了微波辐射对前驱体物相组成及催化剂微观结构的影响. 结果表明: 在微波辐射老化条件下, Cu/Zn比对催化剂前驱体物相组成影响较大, 微波辐射有利于绿铜锌矿(Cu, Zn)₅(CO₃)₂(OH)₆晶相选择生成. 当Cu/Zn比为2.0时, 前驱体中含有较多的绿铜锌矿物相, 且结晶较好, 焙烧后形成的催化剂中CuO-ZnO协同作用较强, CuO分散性好, 导致H₂还原温度低, 在浆态床合成甲醇过程中表现出良好的催化活性和稳定性, 甲醇时空收率(STY)达到309.0 g•kg^－1•h^－1, 失活率仅为0.11%/d, 远优于常规水浴加热制备的催化剂.     

Derivatives (Cu/CuO,Cu/Cu2O,and CuS) of Cu superstructures reduced by biomass reductants

Metallic Cu is considered as the promising functional material owing to its high conductivity and harmlessness. Here, metallic Cu which presents a unique interconnected and continuous structure (Cu superstructure) is prepared using Magnolia grandiflora leaves as the biomass reductant, a green process which avoided the release of harmful gases and massive energy consumption. What's more, Cu/CuO, Cu/Cu₂O, and CuS nanosheets with different sizes were fabricated using Cu superstructure as the substrate via facile methods, and the morphology is regulated by controlling the relevant factors. The electrochemical sensors based on the three derivations were fabricated to study the sensing performance of glucose. The unique structure of nanosheets encapsulating Cu superstructure guarantees the excellent conductivity of Cu/CuO and Cu/Cu₂O composites. Moreover, the electrochemical stability is improved owing to the nanosheet protective layer. Although no metallic Cu was maintained in CuS, the integrated multilayer nanosheets endow CuS with short channels for fast interlayer electronic transmission and with structural stability.     

Pt/Cu双金属纳米颗粒的制备及其催化制氢活性

采用化学共还原法合成了聚乙烯吡咯烷酮保护的Pt/Cu双金属纳米颗粒(BNPs),并采用紫外可见吸收光谱、透射电子显微镜、高分辨透射电子显微镜等对所合成的Pt/Cu BNPs进行了表征。研究了化学组成对Pt/Cu BNPs催化Na BH4水解制氢性能的影响。结果表明,所制备的Pt/Cu BNPs平均粒径为1.8~2.3nm,其催化活性远高于单金属Pt和Cu NPs的活性,其中Pt90Cu10BNP的催化活性最高,其在30℃的条件下,催化Na BH4制氢的活性可达6570mol-H2·mol-cat-1·h-1,约为相同粒径的Pt单金属NP的1.6倍。密度泛函理论的计算结果表明,Pt/Cu BNPs优异的催化性能可归因于电荷转移效应,Pt原子与Cu原子之间发生的电子转移使得Pt原子带负电而Cu原子带正电,荷电的Pt和Cu原子成为催化反应的活性中心。     

急性腹泻患儿血清锌、铜及锌／铜比值的初步探讨

对息性腹泻息儿血清锌、铜水平及锌／铜比值关系进行了探讨．认为锌／铜比值变化具有临床意义．