多孔Pd/TiO2-Al2O3催化剂上乙醇完全氧化的研究

利用模板剂-浸渍法制备出了不同焙烧温度下的多孔复合材料TiO2-Al2O3 和Pd/Al2O3-TiO2 催化剂,催化剂用来催化氧化乙醇。样品经过XRD,FT-IR,孔结构分析、TEM、XPS进行表征分析。250℃焙烧的Pd/TiO2-Al2O3催化剂具有最高的乙醇转化率和CO2生成率。高比表面积、均匀分散的金属Pd颗粒和丰富的表面吸附氧是其具有高的催化活性的主要原因。     

前驱物热稳定性对氧化铁/氧化锡制备的影响

氧化铁纳米复合材料具有优越的磁学和催化性能,近年来在癌症诊断及治疗[1-3]、污染治理[4-6]、电磁屏蔽[7-8]等多个领域得到广泛研究.目前有许多研究集中于如何对复合材料的组成、结构和形貌进行设计合成,例如:利用机械球磨法将SnO2和α-Fe2O3粉体混合制备α-Fe2O3/SnO2 复合材料[9];通过共沉淀法将SnO2复合在α-Fe2O3 的表面[4];或者在Fe3O4表面复合一层C和相应的盐,然后通过煅烧制备Fe3O4/ZrO2和Fe3O4/TiO2微球[10-11].     

TiO_2·Al_2O_3/beads光活性的研究

研究以空心玻璃微球为载体 ,用溶胶 凝胶法制备附载型复合光催化剂的过程 .对TiO2 ·Al2 O3/beads光催化活性进行评价 ,并利用XRD、TEM、SEM对附载型复合光催化剂进行表征 ,同时对TiO2 ·Al2 O3/beads的吸附性和比表面进行测试 .结果表明 ,附载型复合光催化剂TiO2 ·Al2 O3/beads光活性显著提高且组分摩尔比存在最佳值 .当n(TiO2 ) /m (Al2 O3) =97/3时 ,其最高光解率为同样降解条件下 ,同样含量DegussaP 2 5TiO2 光解率的 1 5倍左右 .探讨了TiO2 ·Al2 O3/beads光活性提高的主要因素 ,认为纳米尺寸TiO2 和TiO2 ·Al2 O3/beads吸附性是光活性提高的最主要因素 ,另外 ,活化条件和比表面也是影响光活性的主要因素     

轻质高强度C/Al2O3复合气凝胶的制备及表征

采用溶胶-凝胶法和CO2超临界干燥工艺制备RF/Al2O3复合气凝胶,再经高温热处理过程得到轻质高强度C/Al2O3复合气凝胶,研究了不同热处理温度对气凝胶结构的影响,利用氮气吸附、X射线衍射、扫描电子显微镜和透射电子显微镜等手段对气凝胶的结构和性能进行了分析并且测试了不同热处理温度样品的压缩强度。实验结果表明:C/Al2O3复合气凝胶具有均匀的三维网络结构且成块性好,随着热处理温度的升高,气凝胶比表面积和强度均先增大后减小,当1 400℃时,C/Al2O3复合气凝胶比表面积最高,为831 m2.g-1,压缩强度最大,为9.5 MPa。     

纳米晶状磷酸钙盐/Al2O3-Ti生物复合材料的制备与结构表征

0引言众所周知,钛及其合金具有优良的机械力学性能,但其生物活性不足。因此,在金属基体上涂敷一层生物活性涂层,结合金属与生物活性材料的各自优势,已成为世界各国学者研究最为活跃的生物复合材料体系之一。该体系可用于临床医学,作为人体硬组织等的修复替换材料。目前,已开发出多种在金属基体上制备生物活性涂层的工艺和方法。如:等离子沉积法[1]、离子束溅射法[2]、激光熔覆法[3]、溶胶鄄凝胶法[4]、电化学沉积与水热处理合成法[5]、电泳沉积[6]、电结晶[7]等多种方法。但现有涂层材料尚存在一些问题:(1)由于替换材料的高硬度而导致其周围硬组织坏死[8];(2)由于疲劳磨损或热膨胀不匹配引起涂层脱落[9];(3)由于异质相导致生物活性降解[10]。因此,研究新的制备工艺,开发新的生物复合材料体系就显得十分重要。考虑到Al2O3具有优异的抗磨损、耐腐蚀等性能,以及较好的生物相容性,常作为临床选用的人造硬组织承载材料[11],故在本研究工作中,我们首次采用阳极氧化与水热处理复合工艺研制酸式磷酸钙/Al2O3鄄Ti生物复合材料体系。该体系不同于由日本Ishizawa等研制的HAp/TiO2鄄Ti复合体系[12]。主要体现在两...     

Ag2S/Al2O3纳米复合物的水热合成及表征

采用水热技术结合煅烧的方法,成功制备了Ag2S/Al2O3纳米复合物。 通过SEM、EDX、XRD等测试技术对产品进行了表征,证明得到的产品是Ag2S/Al2O3纳米复合物;无孔Al2O3和多孔Al2O3作反应模板得到的复合物的形态和分布不同。     

Fe2O3/TiO2纳米管的制备及其光电催化降解染料废水性能

采用阴极电沉积和阳极氧化法制备了Fe2O3改性TiO2纳米管(Fe2O3/TiO2-NTs)电极,运用场发射扫描电子显微镜、透射电子显微镜、X射线衍射和紫外-可见漫反射光谱等手段对其进行了表征,考察了其光电化学性能,并研究了复合电极光电催化降解甲基橙染料废水的反应性能.结果表明,Fe2O3的负载成功地将TiO2-NTs的光响应区间拓宽到可见光区域,Fe2O3/TiO2-NTs复合电极的光电流密度达到TiO2-NTs电极的3倍.在光电催化反应中,Fe2O3/TiO2-NTs复合电极对甲基橙的脱色效果明显优于TiO2-NTs电极,以Fe2O3/TiO2-NTs为阳极,光照5min,甲基橙溶液的脱色率可达90%以上.     

制备方法对负载型纳米ZrO2/Al2O3复合载体性能的影响

采用浸渍-沉淀法制备了负载型纳米ZrO2/Al2O3复合载体.采用X射线衍射、N2物理吸附、差示扫描量热(DSC)和程序升温脱附等技术考察了浸渍方式和干燥方法对复合载体的表面性能、热稳定性和晶相结构的影响.结果表明,ZrO2/Al2O3复合载体中没有生成ZrO2-Al2O3复合氧化物或固溶体,纳米ZrO2仅负载在Al2O3的表面.微波干燥法制备的ZrO2/Al2O3复合载体的比表面积(158.7 m2/g)较大,最可几孔径为19.4 nm,ZrO2的粒度为4.2 nm,晶相结构为四方相ZrO2.微波诱导作用使ZrO2/Al2O3复合载体表面产生了新的酸碱中心,微波干燥法制备的ZrO2/Al2O3复合载体具有较强的热稳定性,在873~1 073 K范围内DSC曲线没有出现吸热峰,而其它干燥方法制备的复合载体在903~1 023 K范围内出现了较明显的吸热峰,表明复合载体表面的部分四方相ZrO2转变为单斜相ZrO2(m-ZrO2).对超声波处理过的复合载体进行微波干燥能进一步提高纳米ZrO2与Al2O3之间的相互作用,纳米粒子的粒度(3.4 nm)更小,分布更均匀,但没有改变ZrO2的晶相结构.     

TiO2微粒功能化多孔Al2O3膜的光电化学研究

用恒电位法制备了多孔Al2O3薄膜,通过在Al2O3薄膜孔内水蒸汽水解钛酸异丙酯生成了锐钛矿型TiO2微粒,制备出了Al2O3与TiO2微粒的复合薄膜．用XRD,SEM,光电化学方法进行了研究．实验表明：该复合薄膜具有光电转换特性,在光催化、光电化学太阳能转换中具有应用价值．     

NiO/WO3/TiO2-Al2O3催化剂上正庚烷的临氢异构化

采用溶胶凝胶法制备了TiO2-Al2O3复合载体,用分步浸渍法制备了NiO/WO3/TiO2-Al2O3催化剂。 在常压连续流动固定床反应器上考察了NiO/WO3/TiO2-Al2O3对正庚烷临氢异构化反应的催化性能。 研究了催化剂中WO3含量、Ni含量、焙烧温度和还原温度及催化反应温度对临氢异构化反应的影响。 采用XRD和BET方法对催化剂进行了表征。 结果表明,当w(WO3)=25%、w(Ni)=10%时,所制备的NiO/WO3/TiO2-Al2O3催化剂对正庚烷异构化反应的催化性能最好,活性可达15.50%,选择性可达84.06%。     

KCl-KBO2-K2CO3, K2MoO4-KBO2-K2CO3, and K2WO4-KBO2-K2CO3 ternary systems

phase diagrams of KCl-KBO₂-K₂CO₃, K₂MoO₄-KBO₂-K₂CO₃, and K₂WO₄-KBO₂-K₂CO₃ ternary systems were studied by a calculation-experimental method and differential thermal analysis (DTA). The coordinates of ternary eutectics were determined to be E ₁: 622°C, 8.5 mol % KBO₂, 56.5 mol % KCl, and 35 mol % K₂CO₃; E ₂: 710°C, 23 mol % KBO₂, 43 mol % K₂CO₃, and 34 mol % K₂MoO₄; E ₃: 710°C, 23 mol % KBO₂, 43 mol % K₂CO₃, and 34 mol % K₂WO₄. The specific heats of melting of the eutectics were determined.     

Solubility in the Na2Cr2O7-(NH4)2Cr2O7-K2Cr2O7-H2O system

Solubility in the Na₂Cr₂O₇-(NH₄)₂Cr₂O₇-K₂Cr₂O₇-H₂O four-component water-salt system at 25, 50, and 75°C was studied for the first time. Phase field boundaries for individual salts and potassium and ammonium dichromate solid solutions, monovariant lines, and invariant points were determined. Experimental data were used to optimize the looped isohydric process of potassium dichromate preparation involving additional salts.     

Li2O-TiO2-SiO2-P2O5和Li2O-TiO2-Al2O3-P2O5体系锂离子固体电解质的制备及性能研究

一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…     

Li2SO4-Na2SO4-H2O和Li2SO4- K2SO4-H2O溶液的体积性质

本文用高精度数字式振荡管密度计测定了288K至318K温度范围内Li₂SO₄ + Na₂SO₄ + H₂O和 Li₂SO₄ + K₂SO₄ + H₂O三元体系的密度。混合溶液的离子强度范围从0.1到4.5 mol.kg_–1,混合溶液中Na₂SO₄和K₂SO₄的离子强度分数为0.2,0.4,0.6和0.8。用密度实验值拟合得到了不同温度下Pitzer离子相互作用模型混合参数θ_V和 ψ_V,模型的计算值与实验值的偏差在±0.002 g.cm_–3以内。用Pitzer模型计算了不同离子强度下三元体系的混合体积。     

The preparation of NbH5(Me2PCH2CH2Me2)2 and NbHL2(Me2PCH2CH2PMe2)2 (L = CO or C2H4)

MMe₅(dmpe) (M = Nb or Ta, dmpe = Me₂PCH₂CH₂PMe₂) reacts with H₂ (500 atm) and dmpe in THF at 60°C to give MH₅(dmpe)_2? NbH₅(dmpe)₂ readily reacts with two mol of CO or ethylene (L) to give NbHL₂(dmpe)₂. The exchange of the hydride ligand with the ethylene protons in NbH(C₂H₄)₂(dmpe)₂ is not rapid on the ¹H NMR time scale (60 MHz) at 95°C.     

NaBO2-NaCl-Na2CO3, NaBO2- Na2CO3-NaMoO4, NaBO2- Na2CO3-NaWO4, and NaBO2-NaCl-Na2WO4 ternary systems

The phase diagrams of the NaBO₂-NaCl-Na₂CO₃, NaBO₂-Na₂CO₃-Na₂MoO₄, NaBO₂- Na₂CO₃-Na₂WO₄, and NaBO₂-NaCl-Na₂WO₄ ternary systems were studied by a calculation-experimental method and differential thermal analysis. The coordinates of ternary eutectics were determined: E ₁: 612°C, 16 mol % NaBO₂, 42 mol % NaCl, and 42 mol % Na₂CO₃; E ₂: 568°C, 12 mol % NaBO₂, 28 mol % Na₂CO₃, and 60 mol % Na₂MoO₄; E ₃: 575°C, 12 mol % NaBO₂, 32 mol % Na₂CO₃, and 56 mol % Na₂WO₄; E ₄: 628°C, 8 mol % NaBO₂, 20 mol % NaCl, and 72 mol % Na₂WO₄; and E ₅: 655°C, 9 mol % NaBO₂, 53 mol % NaCl, and 38 mol % Na₂WO₄.     

Polymorphism in the Sc2Si2O7-Y2Si2O7 system

This paper examines the structural changes with temperature and composition in the Sc₂Si₂O₇-Y₂Si₂O₇ system; members of this system are expected to form in the intergranular region of Si₃N₄ and SiC structural ceramics when sintered with the aid of Y₂O₃ and Sc₂O₃ mixtures. A set of different compositions have been synthesized using the sol-gel method to obtain a xerogel, which has been calcined at temperatures between 1300 and 1750 °C during different times. The temperature-composition diagram of the system, obtained from powder XRD data, is dominated by the β-RE₂Si₂O₇ polymorph, with γ-RE₂Si₂O₇ and δ-RE₂Si₂O₇ showing very reduced stability fields. Isotherms at 1300 and 1600 °C have been analysed in detail to evaluate the solid solubility of the components. Although, the XRD data show a complete solid solubility of β-Sc₂Si₂O₇ in β-Y₂Si₂O₇ at 1300 °C, the ²⁹Si MAS-NMR spectra indicate a local structural change at x ca. 1.15 (Sc_2−xY_xSi₂O₇) related to the configuration of the Si tetrahedron, which does not affect the long-range order of the β-RE₂Si₂O₇ structure. Finally, it is interesting to note that, although Sc₂Si₂O₇ shows a unique stable polymorph (β), Sc³⁺ is able to replace Y³⁺ in γ-Y₂Si₂O₇ in the compositional range 1.86?x?2 (where x is Sc_2−xY_xSi₂O₇) as well as in δ-Y₂Si₂O₇ for compositions much closer to the pure Y₂Si₂O₇.     

Synthesis and characterization of inorganic solid electrolytes of Li2O-SiO2-P2O5 and Li2O-TiO2-SiO2-P2O5 systems

The lithium-ion-conducting inorganic solid electrolytes in the oxide systems Li₂O-SiO₂-P₂O₅ and Li₂O-TiO₂-SiO₂-P₂O₅ were prepared by the solid-state reaction, and the electrolyte pellet made by cold-pressing method had diameter of 13 mm and was about 1 mm thick. Phase identification and surface morphology of the products were carried out by X-ray diffraction and scanning electron microscopy. Ionic conductivity of the pellets was investigated through ac impedance. The results show that the adding of other cations can improve the ionic conductivity of the solid electrolyte, and the sintering temperature and duration can influence the ionic conductivity. The maximum ionic conductivity in the samples is 9.9 × 10⁻⁴ S/cm in the Li₂O-TiO₂-SiO₂-P₂O₅ system. Original Russian Text ? W. Li, M. Wang, Z.H. Li, X.F. Shang, H. Wang, Y.W. Wang, Y.B. Xu, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 11, pp. 1341–1345.     

(H2NC4H8NCH2CH2NH2)(HNCH2CH2NH2)3Zn2Ge2Se8: A new,templated one-dimensional ternary semiconductor stabilized by mixed organic cations

The novel, 1D semiconductor (H₂NC₄H₈NCH₂CH₂NH₂)(HNCH₂CH₂NH₂)₃Zn₂Ge₂Se₈ has been synthesized under solvothermal conditions using N-(2-aminoethyl)piperazine as solvent and templating agent at 200 °C. The material was characterized by single crystal and powder X-ray diffraction, IR and Raman spectroscopy and thermogravimetric analysis. The compound consists of 1D anionic [Zn₂Ge₂Se₈]⁴⁻ chains made of alternating edge-shared [ZnSe₄] and [GeSe₄] tetrahedra that charged balanced by one N-(2-aminoethyl)piperazinium and three piperazinium cations. The optical properties were investigated with solid state UV–Vis/near IR spectroscopy and the results show that the solid is a medium gap semiconductor with an absorption edge at 1.8 eV.     

Ag2Se-Tl2Se-Bi2Se3 quasi-ternary system

The Ag₂Se-Tl₂Se-Bi₂Se₃ quasi-ternary system (system A) was studied using DTA, X-ray powder diffraction, microstructure examination, and microhardness measurements. TlBiSe₂-AgBiSe₂, AgTlSe-AgBiSe₂, AgTlSe-Bi₂Se₃, and Tl₂Se-AgBiSe₂ polytherms, isothermal sections at 500 and 800 K, and liquidus surface projection of system A were constructed. System A is congruently triangulated into the following subordinate triangles: Tl₂Se-AgTlSe-Tl₉BiSe₆ (I), AgTlSe-Tl₉BiSe₆-TlBiSe₂ (II), Ag₂Se-AgTlSe-TlBiSe₂ (III), Ag₂Se-AgBiSe₂-TlBiSe₂ (IV), and AgBiSe₂-TlBiSe₂-Bi₂Se₃ (V). Subsystems I, III, and V are ternary systems with three-phase eutectic equilibrium; system II has a three-phase eutectic, and system IV is characterized by several invariant and monovariant peritectic and eutectic equilibria. Primary crystallization and homogeneity fields were outlined, and the types and coordinates of invariant and monovariant equilibria in system A were determined. A characteristic feature of the title system is an extensive field of solid solutions between high-temperature cubic AgBiSe₂ and TlBiSe₂ phases; this field lies as a continuous belt along the AgBiSe₂-TlBiSe₂ quasibinary section and covers about one-fourth of the surface area of the triangular diagram of system A.