CuO-CeO2-ZrO2/HZSM-5催化CO2加氢直接合成DME

采用共沉淀法制备了一系列不同n(Ce)/n(Zr)时的CuO-CeO2-ZrO2甲醇合成催化剂,运用X射线衍射(XRD)、N2物理吸附(BET)和H2程序升温还原(H2-TPR)等手段对催化剂进行了表征分析.将甲醇合成催化剂与HZSM-5分子筛按照一定质量比进行机械混合,CO2加氢直接合成DME双功能催化剂.在固定床反应器中,温度250℃、压力3MPa、H2/CO2=3/1以及空速1800h-1的条件下,对双功能催化剂进行了活性评价.结果表明,当n(Ce)/n(Zr)=1/1时,CO2转化率最高;当n(Ce)/n(Zr)-1/3时,DME的选择性最好,Ce的加入并未有效降低CO的含量.     

Fe添加对Cu/Zn/ZrO2催化剂CO2加氢合成低碳醇性能的影响

采用共沉淀法制备了添加不同Fe含量的Cu/Zn/ZrO2催化剂,在523 K、3.0 MPa和3000 h-1的条件下,考察了不同Fe含量对Cu/Zn/ZrO2催化剂上CO2加氢合成低碳混合醇性能的影响.并采用低温N2吸附、X射线衍射(XRD)、程序升温还原(H2-TPR)和CO2程序升温脱附(CO2-TPD)技术对催化剂进行了表征.结果表明:在Cu/Zn/ZrO2催化剂中加入适量的Fe后,可以提高催化剂的活性、醇的时空产率(STY)以及C2+醇的选择性.     

纳米ZnO/CeO2抗紫外剂制备工艺研究

以Zn(NO3)2·6H2O、Ce(NO3)3·6H3O、(NH4)2CO3·H2O和PEG400为原料,采用直接沉淀法制备ZnO/CeO2抗紫外剂复合粉体,用XRD测试了纳米颗粒的粒径,研究了n(Zn2+)/n(Ce4+)、PEG400的用量、煅烧温度的最佳工艺,结果表明n(Zn2+)/n(Ce4+)为1∶3、PEG400用量为3mL、煅烧温度为500℃时效果最佳.     

n（Zn）/n（Zr）对催化剂CuO-ZnO-ZrO2的结构及其合成甲醇性能的影响

采用并流沉淀法制备了一系列不同n(Zn)/n(Zr)时的CuO-ZnO-ZrO2甲醇合成催化剂,运用X射线衍射仪(XRD)、N2物理吸附(BET)和H2程序升温还原(H2-TPR)等手段对催化剂进行了表征分析。在固定床反应器中进行CO2加H2合成甲醇的活性评价研究,考察了n(Zn)/n(Zr)在催化剂中的作用。结果表明,当n(Zn)/n(Zr)=4/1时,CO2转化率最高;当n(Zn)/n(Zr)=1/4时,甲醇的选择性最好;当n(Zn)/n(Zr)=4/1或1/4时,有效降低了副产物CO的含量,此时的甲醇催化活性最好。     

元素(Ce、Co、La、Sn)掺杂对V-Mo/TiO2催化剂脱硝活性的影响

采用浸渍法制备了一系列V-Mo/TiO2催化剂,考察了钒含量、钼含量及元素(Ce、Co、La、Sn)掺杂对催化剂脱硝活性的影响,并利用XRD、BET、H2-TPR、NH3-TPD及XPS等方法对催化剂的理化性能及结构进行了表征.结果显示,钒最佳含量为3％,钼最佳含量为6％.将Ce、La、Co、Sn掺杂到3％V2 O5-6％MoO3/TiO2中,催化剂的脱硝效率明显提高,其中,3％V2 O5-6％MoO3-1％SnO2/TiO2催化剂表现出最佳的脱硝活性,在180℃具有良好的脱硝稳定性,在引入10％(体积分数)H2 O和0.03％(体积分数)SO2后,表现出良好的抗SO2/H2 O的性能.这主要是由于引入的金属元素以氧化物或钒酸盐形式存在,并与活性组分钒物种有很强的相互作用,抑制了TiO2晶粒的长大,起到了细化TiO2粒径的作用,增加了催化剂表面的弱酸性位点,同时,表面活性氧及还原态的V4+、Mo4+物种数量有了大幅提升,增大了催化剂的还原程度,有利于催化还原反应的进行.     

Cu-Zn-Al2O3-ZrO2催化剂上甲醇部分氧化-蒸气重整耦合制氢反应动力学

在改进的共沉淀法制得的Cu-Zn-Al2O3-ZrO2催化剂上常压连续流动微反应器中研究甲醇部分氧化-蒸气重整耦合制氢反应动力学。实验测得甲醇∶水∶氧=0.45∶0.45∶0.10;1.5∶1.0∶0.20和1.0∶2.0∶0.20三种摩尔配比,200～340℃温度范围内的动力学实验数据,建立了动力学模型,确定了动力学参数。     

Cum-Fen/Ti1-xSnxO2复合催化剂的脱硝性能及抗硫活性

采用共沉淀法制备Ti1-x Snx O2复合氧化物,浸渍负载质量分数10％的CuOx和FeOy活性组分,制备一系列Cum-Fen/Ti1-x Snx O2催化剂.探究不同Ti/Sn和Cu/Fe(物质的量比)对Cum-Fen/Ti1-x Snx O2催化剂的NH3-SCR反应活性的影响.研究结果表明,Ti0.67 Sn0.33 O2载体可促进活性组分CuOx和FeOy的相互作用.当Cu/Fe为3:1时,在300℃ 下NOx的转化率达到91.3％;向反应体系通入286 mg/m3 SO2反应3 h后,NOx的转化率仅下降2.6％.X射线光电子能谱(XPS)、程序升温还原(H2-TPR)、程序升温脱附(NH3-TPD和NOx-TPD)的表征表明,CuOx和FeOy之间存在相互作用,与单一的Cu/Ti0.67 Sn0.33 O2和Fe/Ti0.67 Sn0.33 O2对比,复合催化剂表面吸附氧浓度相对增加15％ ～33％,总酸量增大56％,从而提高了催化剂脱硝活性.     

超临界抗溶剂法纳米Al_2O_3-ZrO_2颗粒的制备与表征

以CO2为抗溶剂介质,无水乙醇为溶剂,采用超临界抗溶剂法(SAS)制备了纳米Al2O3-ZrO2复合氧化物颗粒的前驱体—纳米Al(NO3)3-Zr(NO3)4颗粒,系统考察了温度和压力等因素对制备过程的影响,并对前驱体中Al、Zr组分的共抗溶剂效应进行了研究,通过焙烧前驱体Al(NO3)3-Zr(NO3)4制得了纳米Al2O3-ZrO2球形颗粒.采用热重质谱(TG-MS)、X射线衍射(XRD)、X射线光电子能谱(XPS)、场发射透射电镜(FEG-TEM)和程序升温还原(TPR)等技术对所制备的前驱体Al(NO3)3-Zr(NO3)4和Al2O3-ZrO2纳米颗粒的物化性能进行了表征,初步考察了Al2O3-ZrO2纳米颗粒负载Ni催化剂的还原性能.研究发现,该纳米复合氧化物比用浸渍?沉淀法制得的Al2O3-ZrO2载体对活性组分Ni具有更好的分散性能,作为新型催化剂载体材料有良好的应用前景.     

La掺杂Ni-SiO2催化剂催化裂解甲烷制备氢气和碳纤维

采用浸渍法制备了不同La掺杂量的Ni-SiO2催化剂,研究了La掺杂量对Ni-SiO2催化剂的Ni活性金属粒径、还原性能、甲烷催化裂解寿命以及反应后生成碳纤维的影响.结果表明:La、Ni物质的量比由0增长至0.3时,Ni-SiO2催化剂的寿命显著提高,而当La、Ni物质的量比由0.3增长至0.6时,催化剂寿命在一定程度上略有降低;La、Ni物质的量比由0增长至0.6时,还原后催化剂Ni金属的平均粒径从26.43nm不断降低至10.57nm.不同La掺杂量Ni-SiO2催化剂甲烷催化裂解过程中Ni金属平均粒径变化趋势明显不同,n(La)∶n(Ni) =0的Ni-SiO2催化剂随反应进行Ni金属平均粒径不断降低,而n(La)∶n(Ni)=0.3的Ni-SiO2催化剂随反应进行Ni金属平均粒径则不断升高.碳纤维形态受掺La掺杂量影响较大,随La、Ni物质的量比由0增长至0.3,反应过程中生成的碳纤维管径变粗,而随La、Ni物质的量比由0.3增长至0.6,碳纤维变短.     

Cu/V2O5-TiO2的结构、光吸收性能与催化反应性能研究

用溶胶 凝胶法制得复合半导体 V2O5 TiO2,用等体积浸渍法制得Cu/V2O5 TiO2 光催化剂。利用X射线衍射(XRD)、拉曼光谱(Raman)、程序升温还原(TPR)、红外光谱(IR)、X 射线光电子能谱(XPS)、紫外可见漫反射光谱(UV VisDRS)和光反应器等技术研究了 Cu/V2O5 TiO2 的物相结构、光吸收性能和光催化反应性能。结果表明:含量为 10%(质量分数)的V2O5 单分子层分散在 TiO2 表面;V2O5 负载量超过单分子层分散(> 10% (质量分数))有晶相V2O5 生成,光吸收性能下降;负载金属 Cu 促进四面体配位V向八面体配位 V转化,使 TiO2 光吸收限发生蓝移,对可见光部分的吸收明显增加,拓宽了催化剂的光响应范围,提高了材料的光催化性能, CO2 和C3H6 合成MAA反应的光量子效率显著增加;催化剂的光吸收性能与反应性能呈顺变关系,Cu/10%V2O5 TiO2 的催化活性优于其它含量的催化剂,光量子效率达到15.5%。     

Preparation and phase studies of the ternary semiconducting compounds ZnSnP2, ZnGeP2, ZnSiP2, CdGeP2, and CdSiP2

ZnSnP₂, ZnGeP₂, ZnSiP₂, CdGeP₂ and CdSiP₂ have been prepared in single or polycrystalline form by direct synthesis from the elements, combination of the group IV element with the II-V₂ phosphide, vapour transport or solution growth. Differential thermal analysis and X-ray powder diffraction studies have been used to determine the temperatures of phase transitions in each of these compounds. Of particular interest is the observation of a phase transition in CdSiP₂ at 1098° C some 22° C below the melting point. The thermal analysis studies of ZnSnP₂ indicate a peak, the cause of which is uncertain, at 720° C which is well separated from the melting temperature of 930° C; further ZnSnP₂ does not appear to be congruently melting and has a freezing point at 970° C. c/a ratios have been determined for all five compounds to 1 part in 2000.     

Growth of IrO2, SnO2, and SnO2:IrO2 crystals

Crystals of IrO₂, SnO₂, and SnO₂:IrO₂ have been grown by chemical vapor transport. The IrO₂ crystals are larger than any previously reported. The SnO₂ and SnO₂:IrO₂ crystals are optically clear and are suitable for optical properties studies. This is the first report on the growth of SnO₂:IrO₂ crystals.     

High-Frequency Point-Contact Spectroscopy of TiSi2, TaSi2, and VSi2

High-frequency point-contact spectroscopy as well as conventional low-frequency PC spectroscopy has been used for determining the spectral functions of the electron-phonon interaction (EPI) for three disilicides TiSi₂, TaSi₂, and VSi₂. The temperature dependences of resistivity have been calculated from obtained EPI functions. Comparison of calculated dependences with known experimental data allowed correction of the electron-phonon interaction constants for the studied disilicides.     

Mass Spectrometric Study of NF2, NF3, N2F2, and N2F4

Appearance potentia’s have been measured for selected ions from NF₂, NF₃, N₂F₂, and N₂F₄. Ionization-dissociation processes are identified and bond dissociation energies are calculated. In addition, the bond dissociation energy, D(F₂N–NF₂), has been directly measured to be 5.14±0.38 kj/mole (21.5± 1.6 kcal/mole). A summary is made of available thermochemical and mass spectrometric data for N–F compounds and some evidence is presented to support the designation of cis and trans structures for the N₂F₂ isomers.     

Electrical and tensile properties of Cu-ThO2, Au-ThO2, Pt-ThO2 and Au-Al2O3, Pt-Al2O3 alloys

Dispersion-strengthened alloys of Pt, Au and Cu containing ThO₂ and Al₂O₃ were prepared by precipitating the elements from a solution containing a suspension of the oxide phase. The precipitate deposited on the oxide particles of 0.05μm average diameter and produced dispersions of good homogeneity on compaction. Alloys containing less than 2 vol% oxide phase had sufficient ductility to permit fabrication of wire. Tensile strength and elongation, hardness, and electrical resistivity were measured as a function of temperature up to 1000°C. The dispersion-strengthening caused a relatively small increase in the resistivity of the alloys compared to the resistivity of the metals. The alloys are useful where high electrical or thermal conductivity combined with superior tensile strength, hardness and oxidation resistance at elevated temperatures, are desirable.     

Low temperature specific heat of VSi2, NbSi2, and TaSi2

We present low temperature specific heat measurements of VSi₂, NbSi₂ and TaSi₂. The three disilicides crystallize in the same hexagonal structure (C40, space group P6₂22). The measured values of the electronic Density of States at the Fermi Energy,D(E_F), are in good agreement with theoretical band structure calculations. The obtained Debye temperatures vary asM ^–1/2 (M is the molar mass of the compound), showing that the interatomic forces are similar in the three disilicides. NbSi₂ and TaSi₂ are found to be superconductors at 0.130K and 0.353K respectively. The variation of the transition temperatures is discussed.Also affiliated with Laboratoire des Matériaux et du Génie Physique, ENSPG, INPG.     

Comparison of the Electronic Structures of La2CuO4, Sr2CuO2Cl2, and Sr2CuO2F2

First-principles cluster calculations are reported of the local electronic structure of the three compounds: La₂CuO₄, Sr₂CuO₂Cl₂, and Sr₂CuO₂F₂. The copper ${\text{3d}}_{x^2 - y^2 } $ and the planar oxygen 2p _σ atomic orbitals exhibit a similar degree of covalency. The out-of-plane orbitals, however, are quite different with the ${\text{3}}d_{3z^2 - r^2 } $ atomic orbital lowered significantly in energy for chlorine and fluorine apical positions.     

Strain engineering in single-, bi- and tri-layer MoS2, MoSe2, WS2 and WSe2

Nano Research - Strain is a powerful tool to modify the optical properties of semiconducting transition metal dichalcogenides like MoS2, MoSe2, WS2 and WSe2. In this work we provide a thorough...     

1,4-二叠氮-2,3-二叠氮甲基-2,3-二硝基丁烷的合成

以硝基甲烷为原料合成了1,4-二叠氮-2,3-二叠氮甲基-2,3-二硝基丁烷,总收率为37.8%。采用1HNMR﹑IR和MS对目标产物及中间体的结构进行了表征。在三羟甲基硝基甲烷的合成中,结合反应机理确定了氢氧化钙的用量为:n(CH3NO2)n(Ca(OH)2)=1001;通过对催化剂浓硫酸﹑三氟化硼—乙醚络合物和对甲苯磺酸的比较,得出对甲苯磺酸为中间体2,2-二甲基-5-羟甲基-5-硝基-1,3-二氧杂环己烷合成的较优催化剂;分别采用2,3-二羟甲基-2,3-二硝基-1,4-丁二醇四硝酸酯和2,3-二羟甲基-2,3-二硝基-1,4-丁二醇四对甲苯磺酸酯与NaN3反应,发现磺酸酯基易离去,叠氮化反应更易进行,收率较高;叠氮化反应的较优溶剂为DMSO。DSC分析表明,1,4-二叠氮-2,3-二叠氮甲基-2,3-二硝基丁烷的分解峰温为223.46℃。