无有机模板剂合成ZSM-5分子筛膜

用不含有机模板剂的方法，在平均孔径为2μm多孔α-Al2O3陶瓷管外表面合成了ZSM-5分子筛膜。采用摩尔组成为12Na2O：100SiO2：2Al2O3：2500H2O，合成的ZSM．5分子筛晶种，晶粒发育完整，粒度在15nm左右。再用摩尔组成为28Na20：100SiO2：1．5Al2O3：5000H2O的晶化溶胶，在种了晶种的支撑体上合成的ZSM-5分子筛膜，经FT-IR分析具有ZSM-5分子筛的典型五元环结构，XRD分析表明有ZSM-5分子筛，SEM表明分子筛膜无明显缺陷，膜厚度约13μm，其对H2的渗透率可达2．3×10^-7mol·（m^-2．s^-1．Pa^-1），H2／N2，H2／CH4，H2／CO2的理想分离因数分别为3．14，2．35，2．71。     

The assembly of ZSM-5 layer on Mg-Li alloy by hot-pressing using silane coupling agent as bond and its corrosion resistance

The synthesis of ZSM-5 (Zeolite Socony Mobile-Five) layer on Mg-Li alloy has so far proved difficult. Here we report an effective strategy to assemble ZSM-5 layer on Mg-Li alloy by hot-pressing, using silane coupling as a bonding agent. The high crystalline ZSM-5 showed that the hexagon crystals appeared to be attached firmly to the support. The corrosion behaviour, assessed by electrochemical measurements, showed that ZSM-5 layer reduced the corrosion activity of Mg-Li alloy. The hot-pressing served as an environmentally friendly, corrosion-resistant coating for Mg-Li alloy. The method can potentially provide a general route to synthesize various, uniform layers on other active metals.     

Preparation and characterization of A-type zeolite/SiO2 molecular sieving membranes

1　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｏｒｇａｎｉｃｍｅｍｂｒａｎｅｆｏｒｇａｓｓｅｐａｒａｔｉｏｎ ,ｌｉｑｕｉｄｐｅｒ ｍｅａｔｉｏｎｉｓｏｎｅｏｆｔｈｅａｄｖａｎｃｅｄｔｅｃｈｎｏｌｏｇｉｅｓ ,ｗｈｉｃｈｗｏｕｌｄｂｅｍｏｓｔｐｏｓｓｉｂｌｅｔｏｂｅｕｓｅｄｉｎｔｈｅｉｎｄｕｓｔｒｉｅｓｏｆｃｈｅｍｉｃａｌｅｎｇｉｎｅｅｒｉｎｇ ,ｅｌｅｃｔｒｏｎ ,ｓｐｉｎｎｉｎｇ ,ｍｅｔａｌｌｕｒｇｙ ,ｐｅｔｒｏｌｅｕｍ ,ａｎｄｍｅｄｉｃｉｎｅｅｔｃ .Ｃｅｒａｍｉｃｍｅｍｂｒａｎｅｓｗｉｔｈａｎａｖｅｒａｇｅｐｏｒ…     

火焰喷淬制备BaO-TiO2和La2O3-Nb2O5玻璃微球及性能研究

分别以BaO、TiO2和La2O3、Nb2O5为原料采用火焰喷淬法制备了不含网络形成体的BaTi2O5(BTO)和35La2O3-65Nb2O5 (LNO)玻璃微球。结果表明,所有BTO为透明的、表面光滑、无结晶痕迹的玻璃微球,粒径分布集中在8~40μm,且具有较低的非晶形成能力;而大部分的LNO为透明的、具有光滑表面的玻璃微球,粒径分布集中在10~40μm,少量粒径较大的LNO微球表面粗糙,存在微米级LaNbO4和LaNb3O9晶粒。计算结果显示,BTO和LNO玻璃微球均具有高折射率,分别为2.20和2.23,是非常有应用前景的窗口、镜头以及反光标志膜材料。     

Synthesis of Y2SiO5:Eu nanoparticles from a hydrothermally prepared silica sol

In this paper, a novel route for the synthesis of Y₂SiO₅ (YSO) nanoparticles doped with Eu³⁺ ions, based on the use of a hydrothermally prepared silica sol as a chemical precursor and nanostructuring template, is presented. X-ray powder diffraction revealed crystallization of nanoparticles in an X₁ monoclinic structural type (P2₁/c) with well pronounced diffraction peaks and without any sign of additional phases. Transmission electron microscopy showed that the particle diameter was around 40 nm and that the particles formed loose aggregates. The synthesized materials exhibited characteristic luminescence emission of the trivalent europium ion, with the strongest emission (⁵D₀ → ⁷F₂ transition) at 611.5 nm and a corresponding lifetime of 1.8 ms. Two site occupancy, as expected, were demonstrated.     

Synthesis and electrochemical properties of nanocrystalline Li[Li1／3Ti5／3O4] by complex sol-gel method

1　INTRODUCTIONSpinelLi[Li1/3Ti5/3O4 ]isaveryattractiveelec trodematerialforitsexcellentcyclelifeandpromisingchargingrateinrechargeableenergystoragecells .Duringelectrochemicalreactionsconsistingofelectronandlithiumioninsertionintoorextractionfromit,itslatticeconstantchangesveryslightly ,soitiscon sidereda“zero strain”insertioncompound[13] .Thismaterialwassuccessfullyusedasanodecoupledwithhighpotentialcathodematerials (LiMn2 O4 ,LiCoO2oractivecarbonfiber)toprovideacellorhybridsu perc…     

Synthesis of ZSM-5 zeolite from metakaolinite: Effects of the SiO<Subscript>2</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> molar ratio,the initial precursor and the presence of organic template agent

Highly crystalline ZSM-5 zeolites are successfully prepared from kaolinite as low cost precursor. The effects of SiO₂/Al₂O₃ molar ratio, the presence of tetrapropylammonium bromide (TPABr) and the initial precursor on the textural properties of the final products have been investigated. Crystallized samples have been characterized by scanning electron microscopy and nitrogen adsorption in addition to X-ray diffraction. The results show that getting pure ZSM-5 zeolite with a high crystallinity degree is directly dependent on the starting precursor as well as on the presence of the organic template highlighting the role of SiO₂/Al₂O₃ molar ratio. The directed-template ZSM-5 sample prepared frommetakaolinite with the smallest particles (crystal size of 700 nm) and a maximum crystallinity of 98% is obtained at a SiO₂/Al₂O₃ molar ratio of 31.69. Increasing the SiO₂/Al₂O₃ molar ratio to 41.13 isrequired to prepare an organic-template free ZSM-5 from metakaolinite with a relative crystallinity of 81%. In order to synthesize ZSM-5 zeolite from the acid-activated metakaolinite as the only silica and alumina sources, a SiO₂/Al₂O₃ molar ratio of 76.19 is used, the maximal crystallinity degree is 79%, with the largest ZSM crystals of about 3000 nm.     

高能球磨辅助固相法制备Zr掺杂的钛酸锂

采用改进的高温固相法合成Zr4+掺杂的Li4Ti5O12,研究了原位包覆技术、高能球磨和金属元素掺杂对其晶型、相结构、颗粒形貌以及电化学性能的影响。结果表明:改进后的高温固相法能有效阻止颗粒团聚、提升颗粒的均匀分散度;Zr4+掺杂能降低电极极化、提升锂离子扩散系数,从而改善电化学性能。所得Li4Ti4.95Zr0.05O12在0.5 C倍率下首次放电比容量达176 mAh·g-1,在40 C高倍率下仍达52 mAh·g-1。另探讨了不同离子半径的Zr4+和Ce4+对掺杂效果的影响,结果表明较小离子半径的元素掺杂效果较好。     

Synthesis of (Bi0.5Na0.5)TiO3 (BNT) and Pr doped BNT using the soft combustion technique and its properties

In this work, bismuth sodium titanate (Bi_0.5Na_0.5)TiO₃ (BNT) and praseodymium (Pr)-doped BNT were successfully produced using the soft combustion technique. The effects of Pr doping on stoichiometry, microstructure, density and dielectric properties were studied. Pure Pr-doped BNT was obtained in all samples containing 5, 10 and 20 mol% Pr after calcination at 800 °C for 3 h. The produced powders were then pressed into pellets and sintered at 1100 °C for 3 h. The very similar ionic radii of Pr³⁺ with Bi³⁺ and Na⁺ made it possible to substitute both Bi and Na. The crystallite size and grain size decreased with increasing Pr amount because Pr acted as grain growth inhibitor, both for calcined powders and for sintered pellets. Maximum density was obtained in 5 mol% Pr-doped BNT, beyond which density decreased. The maximum dielectric constant of 756 was obtained in 5 mol% Pr-doped BNT and decreased at higher levels of Pr doping. Pr doped into BNT also caused a decrease in dielectric loss.     

Synthesis and characterization of Li4Ti5O12 via a hydrolysis process from TiCl4 aqueous solution

Spinel-type lithium and titanium composite oxide Li4Ti5O12 was successfully synthesized via a novel hydrolysis method followed by calcination using titanium tetrachloride(TiCl4) and lithium hydroxide(LiOH H2O) as raw materials. Three major factors, including LiOH concentration, LiOH dosage, and hydrolysis temperature were studied for optimizing the synthetic conditions to obtain a phase-pure Li4Ti5O12. The physical and electrochemical properties of samples were characterized by X-ray diffraction(XRD), thermogravimetric analysis(TGA), fourier transform infrared spectroscopy(FT-IR), scanning electron microscopy(SEM), and constant current discharge–charge test. The FT-IR results indicate the presence of [TiO6]octahedra. The SEM images show that the Li4Ti5O12 precursor obtained is an amorphous solid with an irregular and rough morphology. It is revealed that the phase-pure spinel Li4Ti5O12 powders with well crystallization and regular morphology can be obtained by calcining the precursor at800 °C for 6 h. The constant current discharge–charge tests indicate that the Li4Ti5O12 material delivers an excellent cycling ability, maintaining 93.8 % of its initial specific capacity after 60 cycles at a current density of 0.5C.