SiO2/TiO2柱撑层状钛酸的制备及表征

采用预膨润技术成功制备了SiO2/TiO2柱撑层状钛酸。将氢型钛酸TiO2(H)于正丙胺溶液中利用离子交换方法得到正丙胺插层的钛酸C-3TiO,C-3TiO在正硅酸乙酯和异丙醇钛的混合溶剂中160℃溶剂热处理2天,得到SiO2/TiO2柱撑层状钛酸。利用X-射线衍射,红外光谱,透射电子显微镜,热重-差热分析等手段对材料进行表征,结果表明制备材料具有层状结构,层间距为1.1nm。     

SiO2柱层状钛酸的制备及光催化性能

采用分步反应法制备SiO2柱层状钛酸(SiO₂-H₂Ti₄O₉)光催化材料, 研究了制备过程中烷基胺的链长、胺预撑后的洗涤方式以及与正硅酸乙酯(TEOS)水热反应时间等因素对SiO₂-H₂Ti₄O₉结构的影响. 以亚甲基蓝(Methylene Bule, MB)为探针反应物, 考察了SiO₂柱层状钛酸的光催化性能. 结果表明, 随着烷基胺链长增加, 层间距增大, 有利于在层间引入TEOS; 用1:1的乙醇水溶液洗涤正十二胺撑后的产物的结晶度显著高于用无水乙醇洗涤的产物; 胺撑后的产物与TEOS在130℃条件下水热反应两次可得到层间距为1.45nm、比表面积为148.4m²/g、结构较规整的SiO₂-H₂Ti₄O₉柱层状材料. 该柱层状材料对亚甲基蓝具有较高的光催化活性.     

TiO2/累托石复合材料的制备及其光催化性能研究

以溶胶-凝胶法制备的TiO2溶胶为柱撑液制备了TiO2/累托石复合材料.以X射线粉未衍射(XRD)、透射电镜(TEM)、漫反射光谱(DRS)及液氮吸附等手段对其进行了表征;并以罗丹明B(RB)作为模拟有机污染物,研究其吸附及光催化降解性能.结果表明,和表面吸附TiO2粒子共存于复合材料中的柱撑TiO2将层间域从2.42nm扩展到9.81nm,提高了复合材料的比表面积以及孔体积,从而改善其吸附能力及光催化活性.     

钛柱撑蒙脱石制备及其光催化降解有机污染物研究进展

用特定离子或离子团(柱化液)全部或部分替代可膨胀粘土矿物层间可交换阳离子,并以金属氧化物柱形式固定于其层间形成一类二维多孔材料--柱撑粘土矿物.柱撑粘土矿物具有永久性介孔孔道、高比表面积、高热稳定性和高表面酸性等性质,在吸附和催化领域有重要应用价值.用蒙脱石与钛柱化液反应可制得钛柱撑蒙脱石.钛柱撑蒙脱石除具有柱撑粘土矿物的共有性质外,还具有光催化特性.结合作者的研究,介绍了钛柱撑蒙脱石的制备方法和影响材料制备的主要因素.从纳米材料和光催化材料的角度,介绍了钛柱撑蒙脱石的物化性能尤其是光催化降解有机物的性能特点.综述了钛柱撑蒙脱石应用于光催化降解有机污染物的研究进展.     

纳米孔硅铝层柱蒙脱石复合材料的制备和性能研究

以蒙脱石为原料、十六烷基三甲基溴化铵和十二烷胺为结构导向剂,直接利用正硅酸乙酯和异丙醇铝混合物为层柱前驱体,合成了新型纳米孔径硅铝层柱蒙脱石复合材料。运用XRD、TG、FT-IR和N₂等温吸附-脱附等技术表征复合材料。结果表明:合成材料具有大通道(层间距为3.45 nm)、孔径较大且分布窄(平均孔径为2.0 nm)、高比表面积(S_BET=502.0 m2/g)和高热稳定性(大于750 ℃)。和硅层柱多孔粘土复合材料相比,铝的掺入对孔结构和热稳定性影响较小,但明显提高了酸性和酸强度。      

MMT/SiO2复合载体制备聚乙烯纳米复合材料的探索研究

制备了柱撑结构蒙脱石(MM T)/S iO2复合载体,MM T层间距达3.3 nm,载体比表面积≥720 m2/g。将M gC l2/T iC l4/THF负载于此载体上制备聚乙烯催化剂,活性为30 g~40 g产品/g催化剂,填充量为2.5%~3.0%,此活性的纳米复合材料是一种添加剂,可满足填充聚合物使用要求。以TEM、XRD、DSC等技术研究复合材料结构性能关系及MM T对其结晶熔融行为的影响。结果表明,MM T片层以剥离型和插层型纳米尺度共存,片层均匀分散于聚乙烯中,所得纳米复合材料力学性能比普通复合材料有所提高。     

TiO2/硅灰复合材料的制备及其光催化性能的研究

以钛酸四丁酯为主要原料,无水乙醇做溶剂,冰醋酸做抑制剂,盐酸做负催化剂,采用溶胶凝胶法制备了负载量不同的TiO2/硅灰复合纳米粒子。以甲基橙的降解为模型反应,评价了试样的光催化活性,并采用红外光谱、X射线衍射、扫描电镜等测试手段对其进行了性能表征。结果表明,以硅灰为载体,负载型二氧化钛催化剂较未负载二氧化钛催化剂有更高的光催化活性。     

SiO2柱层状钛酸的制备及光催化性能

采用分步反应法制备SiO2柱层状钛酸(SiO₂-H₂Ti₄O₉)光催化材料, 研究了制备过程中烷基胺的链长、胺预撑后的洗涤方式以及与正硅酸乙酯(TEOS)水热反应时间等因素对SiO₂-H₂Ti₄O₉结构的影响. 以亚甲基蓝(Methylene Bule, MB)为探针反应物, 考察了SiO₂柱层状钛酸的光催化性能. 结果表明, 随着烷基胺链长增加, 层间距增大, 有利于在层间引入TEOS; 用1:1的乙醇水溶液洗涤正十二胺撑后的产物的结晶度显著高于用无水乙醇洗涤的产物; 胺撑后的产物与TEOS在130℃条件下水热反应两次可得到层间距为1.45nm、比表面积为148.4m²/g、结构较规整的SiO₂-H₂Ti₄O₉柱层状材料. 该柱层状材料对亚甲基蓝具有较高的光催化活性.     

多孔Ag/TiO2的制备及其光催化性研究

以工业TiOSO4溶液水解得到的多孔偏钛酸为载体,通过光催化还原法制备了多孔Ag/TiO2光催化剂.用XRD、SEM、EDS及低温氮吸附脱附法对样品进行了表征.以光催化氧化降解亚甲基蓝为目标反应,考察了不同制备条件对样品光催化活性的影响.结果表明,制备的Ag/TiO2为负载有非晶态纳米银粒的锐钛矿型TiO2光催化剂,比表面积高达197m2/g,其光催化活性远优于未载银的TiO2.     

纳米Au在蒙脱石层间的插层组装

以Na基蒙脱石为载体,分别以十二胺和PAA作为插层剂,利用此类插层剂可以捕捉金胶体的特点,使预先制备的金胶体插层于蒙脱石的层间制备组装型纳米金催化剂,并考察了高温焙烧对插层效果的影响。此外,以Au(en2)Cl3作为金的前驱体,研究了利用蒙脱石的阳离子交换特性直接进行纳米金插层组装的可行性。采用X射线衍射(XRD)、荧光分析(XRF)和透射电子显微镜(TEM)对所制备的样品进行了表征,结果表明:基于阳离子交换插层的制备方法未能实现纳米金的插层组装,金颗粒主要负载于蒙脱石片层的外表面,而基于配位俘获机理的插层组装方法所制备的纳米金在蒙脱石层间的插层组装效果良好,高温焙烧虽然导致层间纳米金的迁移,但金的粒径仍然保持在较低的尺寸范围。     

VLE data for CO2-CF2Cl2, N2-CO2, N2-CF2Cl2 and N2-CO2-CF2Cl

Knowledge about vapour-liquid (VLE) is required as a basis of reliable calculations for separation processes. Correlations available for the prediction of T, p, x, y data are less accurate for mixtures at high pressures and mixtures containing supercritical components. The results of VLE experiments are reported and compared with data calculated with equations of state.     

Thermal diffusion in binary mixtures H2-CCl2F2 and H2-CHClF2

Thermal diffusion coefficients were measured in two gaseous mixtures, in which one component was close to the critical temperature, in the pressure range (19.6–127.4)·10⁴ N/m² and at a freon concentration of 0.25–0.8.     

Preparation of ZrO2-CeO2 and HfO2-CeO2 nanopowders

We prepared weakly agglomerated powders of ZrO₂-CeO₂ and HfO₂-CeO₂ solid solutions 5–8 nm in particle size, consisting of monoclinic and tetragonal phases. After heat treatment at 1200°C, the crystallite size was 30 and 14 nm, respectively. We also examined the effect of precipitate freeze drying on the crystallization of hafnia-based solid solutions containing up to 20 mol % CeO₂.     

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.     

Radial GRIN glasses in Li2O-Na2O-Al2O3-TiO2-SiO2 systems

A series of GRIN glass rods have been developed in Li2O-Na2O-Al2O3-TiO2-SiO2 systems. Negative radial refractive index profiles were generated by exchanging Na+ for Li+ ions in these glass rods. It has been observed that TiO2 plays a vital role in increase in the profile depth and maximum change in the refractive index because of its ambivalent nature. Change in the refractive index can be further increased by increasing the concentration of exchanging cation in the base glass.     

Elastic and Electronic Properties of Superconducting CaPd 2 As 2 and SrPd 2 As 2 vs. Non-superconducting BaPd 2 As 2

The first-principles calculations were performed to predict the elastic and electronic properties of the superconducting ThCr₂Si₂-type phases CaPd₂As₂ and SrPd₂As₂ in comparison with the non-superconducting CeMg₂Si₂-type phase BaPd₂As₂. Besides, the same properties were compared for CeMg₂Si₂- and ThCr₂Si₂-type polymorphs of BaPd₂As₂. We found that all these phases are mechanically stable and belong to soft materials with low hardness. The near-Fermi region is formed by the valence states of the blocks [Pd₂As₂] with decisive contributions of Pd 4d states. The values of N(E _F) increase in the sequence: CaPd₂As₂ < SrPd₂As₂ < BaPd₂As₂, i.e. in the reverse sequence relative to the transition temperatures T _C. Thus, the change in T _C cannot be explained by the electronic factor, i.e. by the simple correlation T _C～N(E _F). Most likely the decrease in T _C in the sequence CaPd₂As₂ → SrPd₂As₂ and the absence of a superconducting transition in BaPd₂As₂ are related to the structural factors and the peculiarities of the electron–phonon coupling mechanism.     

Si_2N_2O-Al_2O_3-La_2O_3和Si_2N_2O-Al_2O_3-CaO系统的亚固相关系

本文给出了 Si_2N_2O-Al_2O_3-La_2O_3和 Si_2N_2O-Al_2O_3-CaO 系统的亚固相图。实验结果表明:在 Si_2N_2O-Al_2O_3-CaO 系统中有一个未知结构的新化合物 CaO·Si_2N_2O,在3CaO·Si_2N_2O 和3CaO·Al_2O_3两化合物之间形成连续立方固溶体。而 Si_2N_2O-Al_2O_3-La_2O_3系统中则没有发现新化合物。在两个系统的富 Si_2N_2O区,过量的 Si_2N_2O 与 La_2O_3和 CaO 分别反应形成 Si_3N_4与 La_(10)[SiO_4]_(?)N_2(H-相)(和 CaSiO_3。所研究的这两个三元系统中,分别形成了如下几个四元相容性区。在 Si_2N_2O-Al_2O_3-La_2O_3系统内有:H-Si_3N_4-La_2O_3·Si_2N_2O-La_2O_3·Al_2O_3;H-Si_3N_4-La_2O_3·Al_2O_3-La_2O_3·11 Al_2O_3;H-Si_3N_4-La_2O_3·11 Al_2O_3-Al_2O_3;H-Si_3N_4-Al_2O_3-O′s.s;H-Si_3N_4-O′s.s-Si_2N_2O在 Si_2N_2O-Al_2O_3-CaO 系统内有:Si_3N_4-CaSiO_3-CaO·Si_2N_2O-3CaO·Al_2O_3;Si_3N_3-CaSiO_3-3CaO·Al_2O_3-2CaO·Al_2O_3·SiO_(?);Si_(?)N_(?)-CaSiO_3-2CaO·Al_2O_3·SiO_2-Al_2O_3;Si_3N_4-CaSiO_3-Al_2O_(?)-O′s.s;Si_3N_4-CaSiO_3-O′s.s-Si_(?)N_(?)O