钛硅选择性氧化催化剂的研究进展

过渡金属钼、钨、钛、钒等的高价态络合物能有效催化有机过氧化物进行烯烃的环氧化反应。以Ｍｏ（Ⅵ）络合物在有机相中催化过氧化烃来氧化丙烯生产环氧丙烷的方法称之为间接氧化法，是生产环氧丙烷的主要方法之一。７０年代初，荷兰Ｓｈｅｌ研究所发现Ｔｉ（Ⅳ）高分散负...     

Separation of Actinides and Fission Products Using Titanium-Based Materials

Separation of minor actinides such as americium and curium from lanthanides and other fission products is important for the development of efficient nuclear fuel reprocessing methods. This article describes findings from initial investigations into the use of titanium-based materials for the separation of actinides including americium, plutonium, neptunium, and uranium from fission products including lanthanides, strontium, and cesium. Two types of materials were studied; the first was sodium titanates (ST) that have a layered structure and the second was titanosilicates that have a 3-dimensional tunnel structure. Testing indicated that the layered sodium titanates and tunnel-structured titanosilicate materials exhibit a strong affinity for Am, lanthanides, Sr, and Cs at pH 3 and a significantly reduced affinity for Am and the lanthanides at a higher acid concentration (pH 1). Testing also indicated that the ST material exhibited high affinity for actinides in a pH 3 solution. The addition of complexing agents significantly decreased the sorption of Am and lanthanides.     

Surface modified amorphous titanosilicate catalysts for liquid phase epoxidation

Titanium-containing mesoporous silica has been prepared by silylation of mixed oxides obtained via sol–gel method. These samples displayed enhanced activity in the epoxidation of styrene with Bu^tOOH in comparison to normal xerogels or other titanium-containing catalytic systems. The influence of the extension of the silylation reaction, as well as the use of different silylating agents, have been investigated. Samples were characterised by FTIR, XRF, ²⁹Si-MAS NMR, diffuse reflectance UV–Vis and N₂ adsorption–desorption isotherms, X-ray photoelectron spectroscopy (XPS) and FTIR of adsorbed deuteroacetonitrile. The improvement in the catalytic activity achieved has been related to the removal of OH groups by means of calcination or silylation treatments.     

Shape selectivity as a function of pore size in epoxidation of alkenes with supported titanium catalysts

Reactant shape selectivity of supported titanium catalysts for epoxidation of cyclohexene and 2-hexene has an excellent correlation with the pore diameter of the catalysts. With titanosilicate the preference to cis isomer epoxidation is small compared to TiO₂-SiO₂ probably because of the restriction of its diffusion imposed by the zeolite micropore structure.     

Adsorptive interaction of bisphenol A with mesoporous titanosilicate/reduced graphene oxide nanocomposite materials: FT-IR and Raman analyses

Nanocomposite materials containing graphene oxide have attracted tremendous interest as catalysts and adsorbents for water purification. In this study, mesoporous titanosilicate/reduced graphene oxide composite materials with different Ti contents were employed as adsorbents for removing bisphenol A (BPA) from water systems. The adsorptive interaction between BPA and adsorption sites on the composite materials was investigated by Fourier transform infrared (FT-IR) and Raman spectroscopy. Adsorption capacities of BPA at equilibrium, q _e (mg/g), decreased with increasing Ti contents, proportional to the surface area of the composite materials. FT-IR observations for fresh and spent adsorbents indicated that BPA adsorbed onto the composite materials by the electrostatic interaction between OH functional groups contained in BPA and on the adsorbents. The electrostatic adsorption sites on the adsorbents were categorized into three hydroxyl groups: Si-OH, Ti-OH, and graphene-OH. In Raman spectra, the intensity ratios of D to G band were decreased after the adsorption of BPA, implying adsorptive interaction of benzene rings of BPA with the sp² hybrid structure of the reduced graphene oxide.     

Bactericidal activity of silver nanoparticles supported on microporous titanosilicate ETS-10

The bactericidal activity of Ag nanoparticles supported on microporous titanosilicate ETS-10 was investigated. The nanoparticles were prepared by ion exchange followed by in situ reduction with NaBH₄ and characterized using XRD, XPS, HRTEM, and UV techniques. The Ag nanoparticles immobilized on ETS-10 were found to be stable against leaching with a concentration in an aqueous phase of less than the World Health Organization (WHO) specified secondary minimum concentration level. In comparison with the as-synthesized ETS-10 and Ag-exchanged ETS-10 materials, the ETS-10 materials containing an optimum amount of Ag nanoparticles were observed to exhibit a significantly enhanced bactericidal activity and a longer lifetime towards microorganisms, such as Escherichia coli.     

模拟铯废物钛硅酸盐玻璃的化学稳定性研究

熔制了模拟铯废物钛硅酸盐玻璃，用IR研究了玻璃的结构，用产品一致性试验法（PCT）研究了玻璃的化学稳定性，结果表明，所选组成的配料可以在1100℃熔制得玻璃，样品的密度在3．2703．35g/cm^3之间，玻璃中Ti^4 可能以[TiO4]进入玻璃网络，玻璃的结构主要由[SiO4]和[TiO4]组成，产品一致性试验法（PC）实验的浸出液中主要有R＋离子，当配料中n(TiO2):n(SiO2)为0．40－0．35时，浸出液中各种离子的浓度均较低，表明玻璃具有较好的化学稳定性。     

表面富钛复合钛硅分子筛的合成与表征

以全硅分子筛silicalite-1为硅源,利用水热晶化法合成表面富钛的钛硅分子筛CTS,采用XRD、N2吸附-脱附、IR、XRF、UV—vis、XPS、DTA—TGA和SEM等对合成的分子筛进行表征。结果表明,合成的钛硅分子筛CTS具有MFI拓扑结构,钛物种主要集中在其表面,催化性能评价表明,在苯酚羟基化探针反应中合成的钛硅分子筛CTS具有较好的活性和苯二酚选择性,重复使用次数优于常规利用硅酯为硅源合成的分子筛TS-1。     

Synthesis and characterization of microporous titanosilicate ETS-10 with different titanium precursors

This work was aimed to identify the influence of different titanium sources, namely nano-sized Degussa TiO₂ (commercially known as P25), TiCl₃, TiF₄, and (NH₄)₂F₆Ti, on the crystallization of micropoprous titanosilicate ETS-10. The characterization results of XRD, FESEM, Raman, and FTIR showed that the morphology, particle size, and purity of the final products were strongly dependant on the titanium sources because of the different crystallization mechanisms of ETS-10 in the presence of different titanium precursors. The different coordination states of Ti atoms and anions of the titanium precursors were observed to play a role in the formation of ETS-10.