混合金属络合物羟基铬铝交联蒙托土的合成

用取代法和共聚法合成了不向Cr/Al比的混合金属络合物羟基铬铝交联蒙托土,用XRD、DTA考察了其热稳定性,用~(27)Al-NMR、UV、ESR等技术对柱化溶液中铬和铝的状态进行了研究。结果表明,两种方法均合成出结构相近且底面间距d(001)为1.90～2.49nm的羟基铬铝交联蒙托土。发现Cr/Al比对羟基铬铝聚合物的结构、d(001)值、比表面热稳定性均有较大影响;随Cr/Al比的增加,d(001)逐渐增加,热稳定性下降,但在惰性气氛下热稳定性较好(>500℃)。     

含过渡金属离子的交联蒙托土交联柱中Keggin结构的作用

利用Keggin结构可以发生同晶取代的性质,合成了含过渡金属离子铬、镍的羟基铝交联蒙托土,并运用XRD、~(27)Al-NMR、UV-DRS、XPS、TPR等方法研究了Keggin结构的作用。结果表明,铬、镍都可以和铝生成具有Keggin骨架结构的羟基共聚体,并以此作柱子支撑着蒙托土的层间。铬的取代反应比镍容易发生。共聚法合成出的羟基镍铝交联蒙托土中镍存在两种状态;过量的金属离子对Keggin结构有较大地破坏;Keggin结构的存在增加了交联蒙托土的热稳定性。     

混合金属络合物羟基镍铝交联蒙托土的表面酸性及催化性能

用NH_3-TPD,IR技术研究了混合金属络合物羟基镍铝交联蒙托土的表面羟基和表面酸性。考察了制备方法、Al/Ni比对其表面酸性的影响,同时用异丙苯裂解反应表征了其催化性能。结果表明,交联蒙托土存在L酸和B酸,其中以L酸为主。表面酸性可能来源于柱子和表面羟基,柱子的热稳定性对表面羟基,表面酸性均有较大影响。Ni的引入增加了L酸和B酸,取代法制备的样品具有比共聚法的样品更强的酸性。交联蒙托土具有较好的异丙苯裂解性能,Ni的引入使其活性有较大的增加。     

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。     

羟基铝溶液及铝交联蒙脱土的研究

本文用(27)~Al NMR法和8-羟基喹啉萃取法分别研究了羟基铝溶液中十三聚铝含量的变化规律,还用X-射线衍射法研究了铝交联蒙脱土d_(001)的变化。研究结果表明,铝离子的聚合情况主要由羟铝比决定,而浓度影响不大。随着羟铝比的增加,溶液中单核铝离子含量减少,十三聚铝离子相对含量增加,所得铝交联蒙脱土的d_(001)也随之增大。参照这些变化规律、控制羟基铝溶液的组成,可以制备各种层柱状铝交联蒙脱土复合物。     

铁-锆交联蒙脱土的制备和结构表征

我们首次合成了铁锆复合柱交联蒙脱土, 并用XRD, 比表面及孔径测定和Mossbauer谱学等方法进行了表征。结果表明, 铁锆交联蒙脱土比表面增大为原土的三倍以上, 其层间距可达0.88nm(d001=1.84nm)。热稳定性明显高于单一Fe柱交联蒙脱土。在500℃加热后层间距保持0.63nm~0.71nm。但由于铁柱的坍塌造成微孔减少, 比表面明显下降。Mossbauer谱研究表明, 500℃焙烧单一铁柱转变为α-Fe~2O~3, 而Fe-Zr-PILC中铁仍以超顺磁Fe^3^+存在, 单一铁柱的铁组分在400℃可还原为金属铁, 而铁锆混合柱交联蒙脱土中由于铁与锆之间存在较强的相互作用, 450℃氢气气氛中铁组分仍不能还原为金属铁。     

铈铝柱撑蒙脱土的制备及其负载钴催化剂的费托反应性能

以钠化改型后的内蒙古兴和县蒙脱土为原料, 按照不同的Ce/Al摩尔比合成柱化液,制备铈铝柱撑蒙脱土. 使用XRD, BET, TGA-DTA, ICP和FTIR等方法对柱撑后的蒙脱土进行了表征, 结果表明, 所制备的铈铝柱撑蒙脱土具有高热稳定性, 较大的层间距和高比表面积. 以铈铝柱撑蒙脱土为载体, 使用浸渍法制备了负载钴的柱撑蒙脱土催化剂, 用于费托反应性能评价. 实验结果表明, 交联柱中Ce的引入改变了柱撑蒙托土负载的钴催化剂的性质, 提高了催化活性, 催化剂具有优良的费托合成性能.     

羟基硅铝交联粘土的合成和热稳定性研究

羟基硅铝交联粘土的合成和热稳定性研究孙来生，李栋藩，陶龙骧（中国科学院大连化学物理研究所，大连１１６０２３）关键词蒙脱土，硅铝柱，热稳定性，~（２７）Ａｌ　ＮＭＲ交联粘土作为一种新型催化材料出现以来，其热稳定性一直是重要研究课题，对影响交联粘土热稳定?..     

部份层无序铝交联蒙脱土结构的研究

应用非完整晶体的XRD衍射及阳离子交换量的测定等实验数据, 得出了铝交联蒙脱土的三维结构模型. 结构中Al(III)多数以十三聚体形式进入层间, 层间距为1.97 nm, 几率为0.65, 少数以六聚体形式进入层间, 层间距为1.5 nm, 几率为0.25, 其余10%的层间仅为水分子. 并给出了交联柱子在层间的分布与层单元之间的连接方式. 目前通用的以Bragg公式计算所得的d_(001)值来表征交联浆脱土的层间距是不确切的.     

皂石的合成、表征及其催化性能

用水热法合成了皂石,并用羟基铝低聚物与其交联制得AICLS。用XRD、~(27)Al和~(29)Si MASNMR及吡啶吸附量表征其晶相、结构和表面酸性。合成产物的结晶度很高。皂石中T—O—T片内四面体层上铝量可由合成条件控制,表明交联密度的柱间距与铝量有关。在异丙苯裂解反应中,AICLS的活性高于皂石,但活性衰减较慢;样品的催化裂化活性与探针分子可抵达的强酸中心数有关。     

铁铝复合柱撑粘土的制备、柱结构和稳定性(I)

用两种方法合成了一系列不同Fe/Al比的铁铝复合柱撑牯土(FeAl-PlLC). 用~(27)Al-NMR、UV、ESR等手段考察了柱溶液的结构和状态, 用XRD、DTA、UV-DRS 等技术对其结构、稳定性进行了研究. 结果表明, 铁铝柱撑粘土的底面间距为1.98～1.55 nm, Fe/Al比对其柱结构、比表面积、热稳定性均有较大影响. Fe/Al<0.5时, 层间柱主要呈现Keggin结构, Fe/Al≥0.5时, 可能为三聚结构. 随Fc/Al比的增加, d(001)值, 比表面面、热稳定性逐渐下降.     

对苯乙烯磺酸在水滑石层间的柱撑及聚合

对苯乙烯磺酸在水滑石层间的柱撑及聚合;水滑石;对苯乙烯磺酸;柱撑;聚合     

具有不同层间距的氧化铝柱层状钛铌酸盐的制备

层往金属氧化物是近年来受到人们普遍重视的一类新型多孔材料［‘－‘］．与层状粘土问不同，层状金属氧化物通常无通水膨胀性．因此，要制备热稳定的无机氧化物柱层状金属氧化物是比较困难的．事实上，目前这方面的研究工作大部分都局限在用有机胺来支撑此类层状金足氧化物［’一月．1989年，Cheng等人问首次采用分步交换法制备了具有单一层间距的氧化铝柱层状铁酸盐．作者也报导了大层间距氧化铝柱层状钛酸盐的制各门．由于这类材料的主要用途之一是制作分子筛和择形催化剂，对于不同大小的分子客体就要求具有不同层间距的层柱金属氧化物…     

Fe-Al 柱撑膨润土的制备及其非均相Fenton降解橙黄II

通过离子交换方法制备不同Fe含量的Fe-Al柱撑膨润土,并且研究了其作为非均相Fenton催化剂降解橙黄II的性能.通过X射线粉末衍射(XRD),比表面积(SBET),傅里叶变换红外(FTIR)光谱,拉曼(Raman)光谱和扫描电子显微镜(SEM)研究其结构特征.结果显示,钠化膨润土的层间距为1.24 nm,经过柱撑之后,Al柱撑膨润土的层间距增大到1.77 nm,Fe-Al柱撑膨润土为1.72 nm左右,并且比表面积也有明显增大.XRD和Raman结果表明Fe/(Fe+Al)摩尔比达到20%时,样品中出现α-Fe2O3,膨润土未能形成柱撑.在橙黄II初始浓度为100 mg L-1,催化剂用量为1.0 g L-1,温度为40°C,pH为3.0,H2O2初始浓度为10 mmol L-1的条件下,考察了柱撑膨润土的Fenton催化活性.结果表明,Fe-Al柱撑膨润土的催化性能随着Fe含量的增多先增大后略有降低,当Fe/(Fe+Al)摩尔比为10%时达到最大,橙黄II溶液在4 h内色度去除率和化学需氧量(CODCr)去除率分别达到100%和87.73%,并且降解反应为非均相Fenton反应.研究了Fe-Al柱撑膨润土的重复使用性.催化剂循环使用4次,仍然具有良好的活性.     

Characterization of cationic pillared layer clays

Na-montmorillonite and its Al-, Ti-, Fe-, Cr-, Zr- and Sn-pillared derivatives (pillared layer clays) were prepared and characterized by instrumental methods and a chemical reaction. Structural characterization involved X-ray fluorescence (XRF) analysis, X-ray diffractometry (XRD),²⁹Si and²⁷Al MAS NMR spectroscopies, thermogravimetric (TG) and BET measurements. By the distinctly characteristic shapes of the d₀₀₁ vs. temperature curves two groups could be distinguished, (i) Al-PILC, Ti-PILC, Cr-PILC, Zr-PILC and (ii) Fe-PILC, Sn-PILC, Na-montmorillonite. On montmorillonite isomerization of cyclopropane only occurred while oligomerization followed isomerization over Al-PILC. This latter reaction was attributed to Lewis and (the considerably smaller number of) Br?nsted acid sites whose number, strength and accessibility increased due to pillaring.     

交联蒙脱土负载型Cu催化剂用于CH4燃烧反应的研究

在蒙脱土原粉中引入Al-、AlZr-、AlCe-交联剂，分别制备交联蒙脱土。测试表明：与蒙脱土原粉相比，Al-、AlZr-、AlCe-交联蒙脱土的底面间距明显增大，热稳定性显著提高；AlZr-、AlCe-交联蒙脱土的底面间距比Al-交联蒙脱土更大，热稳定性更高。以交联蒙脱土为载体，制得负载型Cu催化剂，考察了它们对甲烷燃烧反应的催化活性。结果表明：AlZr-、AlCe-交联蒙脱土催化剂活性明显高于Al-交联蒙脱土催化剂，反应温度为550 ℃时，甲烷在AlZr-、AlCe-交联蒙脱土催化剂上的转化率约90%。     

Synthesis and Characterization of New Material——La/Zr/MMT Employed in Acetone Oxidation

A new material of zirconium pillared montmorillonite added with lanthanum （denoted as La/Zr/MMT） was prepared for acetone oxidation. Surface properties of the catalysts were investigated by means of XRD, TEM, TG-DTA and BET methods. The XRD result indicated that the interlayer space of the montmorillonite was enlarged from 1.57 to 4.85 um after the treatment with zirconium pillaring and the addition of lanthanum. N2 adsorption-desorption result showed that by the process of zirconium pillaring, the specific surface area of the sample was increased to 128.0 m^2/g, which was two times almost as large as pure montmorillonite. Simultaneously, the thermal stability was also enhanced. The activity of the new material on the total oxidation of acetone was investigated, and the results indicated that the catalytic activity of the montmorillonite was greatly improved. Over the sample of La/Zr/MMT, the T98 of acetone was obtained at 350 ℃, while it needs 400 ℃ over the pure montmorillonite. After 0.1% Pd was supported on the sample of La/Zr/MMT, the T98 decreased from 350 to 280 ℃, indicating the montmorillonite is a promising material for the control of some types of the volatile organic compounds such as acetone.     

Mixed Al/Ce oxide pillaring of montmorillonite: XRD and UV-VIS diffuse reflectance study

Ce and Al pillared clays were prepared by (i) pillaring Ce³⁺-exchanged montmorillonite with Al₁₃ polycation (Ce-Al-PILC) and (ii) by pillaring Na-montmorillonite with an oligomer obtained from cohydrolysis of Ce³⁺ and Al³⁺ salts (Al-Ce-PILC). Cohydrolyzed oligomer gives larger intercalating species with Ce³⁺ incorporated in it. The UV-DRS spectrum of clay sample intercalated with this species shows four distinct absorption bands at 224, 263, 294 and 342 nm, which are attributed to the 4f-5d interconfigurational transitions of Ce³⁺ ions associated with alumina pillars.     

Development of Thiolated Chitosan Nanoparticles Based Mucoadhesive Vaginal Drug Delivery Systems

The aim of the present study was to evaluate the influence of the chitosan chain length on the drug loading and releasing in VFS (vaginal fluid simulant). Thiolated chitosan nanoparticles (TCS-NPs) were prepared using thioglycolic acid and 1-ethyl-3-3-(3-dimethylaminopropyl)carbodimide hydrochloride (EDC) and characterized with FTIR. The degree of thiol substitution was found out by Ellman’s method. TCS-NPs were developed using ionic cross-linking reaction with pentasodiumtripolyphosphate (TPP). Curcumin (CUR) loaded nanoparticles were obtained by encapsulation. DLS and SEM characterized these NPs with diameter between 200 ± 50 nm. Zeta potential of NPs was 11–38 mv. The maximal encapsulation efficiency was 86.26%. The in vitro drug release studies in VFA at pH 4.2 showed a sustained release profile over a period of 3 days.