New three-dimensional inorganic frameworks based on the uranophane-type sheet in monoamine templated uranyl-vanadates

Seven new uranyl vanadates with mono-protonated amine or tetramethylammonium used as structure directing cations, (C₂NH₈)₂{[(UO₂)(H₂O)][(UO₂)(VO₄)]₄}·H₂O (DMetU5V4) (C₂NH₈){[(UO₂)(H₂O)₂][(UO₂)(VO₄)]₃}·H₂O (DMetU4V3), (C₅NH₆)₂{[(UO₂)(H₂O)][(UO₂)(VO₄)]₄}·H₂O (PyrU5V4), (C₃NH₁₀){[(UO₂)(H₂O)₂][(UO₂)(VO₄)]₃}·H₂O (isoPrU4V3), (N(CH₃)₄){[(UO₂)(H₂O)₂][(UO₂)(VO₄)]₃}·H₂O (TMetU4V3), (C₆NH₁₄){[(UO₂)(H₂O)₂][(UO₂)(VO₄)]₃}·H₂O (CHexU4V3), and (C₄NH₁₂){[(UO₂)(H₂O)][(UO₂)(VO₄)]₃} (TButU4V3) were prepared from mild-hydrothermal reactions using dimethylamine, pyridine, isopropylamine, tetramethylammonium hydroxide, cyclohexylamine and tertiobutylamine, respectively, with uranyl nitrate and vanadium oxide in acidic medium. The structures were solved using single-crystal X-ray diffraction data. The compounds exhibit three-dimensional uranyl-vanadate inorganic frameworks built from uranophane-type uranyl-vanadate layers pillared by uranyl polyhedra with cavities in between occupied by protonated organic moieties. In the uranyl-vanadate layers the orientations of the vanadate tetrahedra give new geometrical isomers leading to unprecedented pillared systems and new inorganic frameworks with U/V=4/3. Crystallographic data: (DMetU5V4) orthorhombic, Cmc2₁ space group, a=15.6276(4), b=14.1341(4), c=13.6040(4) Å; (DMetU4V3) monoclinic, P2₁/n space group, a=10.2312(4), b=13.5661(7), c=17.5291(7) Å, β=96.966(2); (PyrU5V4), triclinic, P1 space group, a=9.6981(3), b=9.9966(2), c=10.5523(2) Å, α=117.194(1), β=113.551(1), γ=92.216(1)°; (isoPrU4V3) monoclinic, P2₁/n space group, a=10.3507(1), b=13.6500(2), c=17.3035(2) Å, β=97.551(1)°; (TMetU4V3) orthorhombic, Pbca space group, a=17.1819(2), b=13.6931(1), c=21.4826(2) Å; (CHexU4V3), triclinic P−1 space group, a=9.8273(6), b=11.0294(7), c=12.7506(8) Å, α=98.461(3), β=96.437(3), γ=105.955(3)°; (TButU4V3), monoclinic, P2₁/m space group, a=9.8048(4), b=17.4567(8), c=15.4820(6) Å, β=106.103(2).     

Pillared clays as efficient catalysts for cyclohexanol oxidation

Summary Iron, aluminium and mixed iron aluminium pillared clays were prepared by partial hydrolysis method and doped with 10% V and Mo. The samples were characterised by XRD, FTIR and surface area and pore volume measurements. Oxidation of cyclohexanol with hydrogen peroxide was done as probe reaction to test catalytic activity. Iron pillared systems exhibited maximum activity. The effects of various reaction variables on the reaction were studied.     

Study on fire retardant mechanism of nano-LDHs in intumescent system

This paper investigated the fire-retardant mechanism of the nano-LDHs in the intumescent system by the temperature programmed oxidation (TPO). Researches were also conducted to explore the function of the nano-LDHs in the composite fire-retardant agents in air and nitrogen atmosphere, respectively. The results indicated that the nano-LDHs species were responsible for the catalytic oxidation of the rich-carbon compound in oxygen atmosphere. In addition, the nano-LDHs species and their calcinated products at high temperature could increase the carbonaceous residue-shield of the carbon-rich materials, improve the quality and the graphitization degree of the formed char-layer, and accelerate the intumescence and expansion of the melting carbon-rich materials to a certain degree under the oxygen-free condition, leading to the carbonization and expansion of the intumescent layer.     

高层间距的羟基硅铝交联蒙托土的合成与表征

采用溶胶分散法合成了一系列高层间距(2.6nm)的羟基硅铝交联蒙托土(SiAl-CLM),并用~(27)Al NMR、XRD、DTA、XPS、吡啶吸附-IR、正丁胺吸附-TPD等技术进行了表征,用脉冲反应技术考察了其催化活性。结果表明:SiAl-CLM层间存在氧化硅胶团与羟基铝聚体形成的复合Si-Al柱.SiAl-CLM的热稳定性较好,对异丙苯的裂解活性(76.8％)较高。Si的引入增加了交联蒙托土的表面酸性,尤其增加了Bronsted酸性。     

Synthesis and characterization of poly(styrene-co-methyl methacrylate)/layered double hydroxide nanocomposites via in situ polymerization

Intercalated poly(styrene-co-methyl methacrylate)/layered double hydroxide nanocomposites (PS-PMMA/LDH-B) have been synthesized by the in situ bulk multistep polymerization of styrene and methyl methacrylate in the presence of the Ca-Al layered double hydroxide, previously modified by the incorporation of benzoate anions [Ca₄Al₂(OH)₁₂(C₆H₅COO)₂·xH₂O, LDH-B]. Nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). XRD and TGA results pointed to the successful incorporation of the LDH-B within the copolymer matrix. XRD results indicated that the characteristic layered structure of the LDH-B had disappeared due to disordering. TEM analysis confirmed that LDH-B was partially dispersed within the matrix forming a structure with alternating matrix-particle regions, where particles appear in a form of intercalated nanocomposite structure. TGA results showed improved thermal properties in comparison to the neat PS-PMMA copolymer.     

Preparation of Zn2+–Ni2+–Fe3+–CO32−LDHs and study of photocatalytic activities for decomposition of Methyl Orange solution

New type photocatalytic materials of Zn²⁺–Ni²⁺–Fe³⁺–CO₃^2?LDHs were prepared by complexing agent-assisted homogeneous precipitation technique and Zn(NO₃)₂·6H₂O, Ni(NO₃)·6H₂O, Fe(NO₃)₃·9H₂O used as raw materials in the case of molar ratio of Zn²⁺/Ni²⁺/Fe³⁺ = 1:6:2. Zn²⁺–Ni²⁺–Fe³⁺–CO₃^2?LDHs having a specific surface area of 96.5 m²/g. The structure and catalytic properties of the material were systematically studied. The experimental results show that the Zn²⁺–Ni²⁺–Fe³⁺–CO₃^2?LDHs has a higher adsorption performance and lower band gap which make it an excellent catalyst for reducing the degradation of the methyl orange. Study on the process of photocatalytic reaction shows that Methyl Orange was adsorbed to the layer of Zn²⁺–Ni²⁺–Fe³⁺–CO₃^2?LDHs, and then it was photodecomposed to inorganic molecules and ions by Zn²⁺, Ni²⁺, and Fe³⁺ on the surface of Zn²⁺–Ni²⁺–Fe³⁺–CO₃^2?LDHs.     

水滑石阻燃剂的离子改性研究进展

由于水滑石具有层板阳离子可调控、层间阴离子可交换、酸碱性等独特的性能,在医药、离子交换、催化、材料阻燃等领域备受研究者关注。特别是水滑石用作阻燃材料时,具有无卤、无毒、不产生有毒和腐蚀性气体、阻燃和抑烟性能优良等突出优点,已成为当前材料阻燃领域研究的热点。然而,水滑石也存在热稳定性较差、容易聚集、分散性较差等缺点,故国内外学者开展了一些水滑石阻燃剂改性的系列研究。本文阐述了近年来国内外学者利用Ca2+、Mg2+、Al3+等阳离子对水滑石阻燃剂进行改性,以及应用BO33-、SiO32-等阴离子对水滑石阻燃剂进行改性等方面的研究进展,并对水滑石在生物质材料阻燃、低成本水滑石阻燃剂的合成、水滑石协效阻燃剂的研究、水滑石阻燃剂工业化生产新工艺与设备、洁净化制备技术等方面的研究与应用前景进行了展望。     

TiO2柱撑蒙脱土的制备及其对品红降解的催化反应

基于TiO2光催化剂的优良光催化活性,采用酸性溶胶法合成了TiO2柱撑蒙脱土复合光催化剂,利用IR,UV-Vis,TG/DTA,XRD及SEM等手段对复合催化剂进行了表征,通过太阳光对酸性品红光催化降解实验,考察了催化剂的光催化活性。该催化剂比纳米TiO2对酸性品红的光催化降解反应表现出更高的催化活性,而且更易于沉降、回收。当TiO2柱撑蒙脱土光催化剂的用量为0.2 g.(100 mL)-1,酸性品红溶液的pH值为3时,在太阳光下40 min内酸性品红基本降解完全,而且该降解过程符合Langmuir-Hin-shelwood方程。X射线衍射(XRD)分析表明钛柱撑蒙脱土的层间距较钠基蒙脱土有明显的增大,紫外-可见吸收光谱表明TiO2柱撑蒙脱土比纳米TiO2具有更高的光吸收效率。     

CoxNi1-x层状双氢氧化物复合材料的制备及其超级电容器性能

通过化学共沉积方法制备了具有高比电容的介孔CoxNi1-x层状双氢氧化物(LDHs)复合材料。采用电子能谱、红外、X射线衍射、场发射扫描电镜等表征了产物的组成、结构和形貌。循环伏安、恒电流充放电等测试表明,Co0.5574Ni0.4426LDH复合材料具有最佳的电容性能,在1A/g的电流密度下,比电容高达2552F/g,且循环1000周后,比电容仍能保持90.6%,呈示该复合材料具有优异的电化学性能。     

大比表面层柱磷酸锡的制备和催化性能

详细研究了氧化铬层柱磷酸锡的制备规律，革新了文献中丙胺在量季铵盐的两步胶体化法，用有机胺使层板一步胶体化成功地制备了高比表面积的层柱磷酸锡，其最高比表面积达４４５ｍ＾２／ｇ。样品经４００℃焙烧后仍具有良好的层柱结构，可形成规整的平行板型中孔，孔径集中在１．７￣５ｎｍ范围内。丙醇脱水和异丙苯裂解反应表明氧化锆层柱磷酸锡具有弱酸催化活性；环己烷脱氢反应表明，氧化铬层柱磷酸锡比负载型氧化铬催化剂有更高的