MoO4^2-插层Mg／Al／Ti—LDHs的结构及其催化性能研究

用共沉淀法制备层板含钛的镁铝钛三元层状双金属氢氧化物（LDHs）,将其作为前驱体,利用离子交换法制备MoO4^2-阴离子插层结构的MoO4^2--LDHs型超分子材料,通过X射线衍射（XRD）、红外光谱（FT-IR）和热重及差热分析（TG—DTA）等对插层化合物及其焙烧产物的结构进行了分析,结果表明,通过共沉淀和离子交换法成功得到晶体结构较为理想的层板含Ti^4＋的三元LDHs以及具有超分子结构的MoO4^2-插层LDH化合物。研究发现,MoO4^2--LDHs在500℃焙烧,产物在丙烯环氧化反应中具有较高的催化活性,这与形成一定结合形式和组成的多元复合金属氧化物有关、     

MoO2-4插层Mg/Al/Ti-LDHs的结构及其催化性能研究

用共沉淀法制备层板含钛的镁铝钛三元层状双金属氢氧化物(LDHs),将其作为前驱体,利用离子交换法制备MoO2-4阴离子插层结构的MoO2/4-LDHs型超分子材料,通过X射线衍射(XRD)、红外光谱(FT-IR)和热重及差热分析(TG-DTA)等对插层化合物及其焙烧产物的结构进行了分析,结果表明,通过共沉淀和离子交换法成功得到晶体结构较为理想的层板含Ti4 的三元LDHs以及具有超分子结构的MoO42-4一插层LDH化合物.研究发现,MoO2-4-LDHs在500 ℃焙烧,产物在丙烯环氧化反应中具有较高的催化活性,这与形成一定结合形式和组成的多元复合金属氧化物有关.     

焙烧复原法制备山梨酸和苯甲酸插层水滑石及其缓释性能研究

焙烧复原法无需有机溶剂,制备流程比较简单,条件容易控制。以水滑石(LDH)为载体,通过焙烧复原法分别将山梨酸(SA)和苯甲酸(BA)插入其层间,制备了SA-LDH和BA-LDH插层材料。采用傅里叶变换红外光谱(FT-IR)、X-射线衍射(XRD)、热重-差热分析(TG-DSC)和扫描电镜(SEM)对其结构和热稳定性进行表征,并研究在不同pH缓冲体系中的缓释性能和机理。结果表明,SA和BA阴离子成功的插入到LDH层间,分散效果得到了明显改善。SA-LDH表现出良好的缓释性能,在pH 4.4、3.4的缓冲溶液中120 min后达到释放平衡,释放量分别为431.34、389.38 mg/g。BA-LDH存在突释现象,缓释性能不佳,释放时间30 min时达到平衡,在pH 4.4、3.4的缓冲溶液中释放量为353.22、304.17 mg/g, SA和BA的释放过程符合准二级动力学方程。焙烧复原法制备的SA-LDH材料具有良好的缓释性能,在防腐保鲜类食品包装材料中的应用具有重要意义。     

不同阴离子插层锌铝水滑石对亚甲基蓝的光催化性能（英文）

采用共沉淀法制备了不同阴离子(硝酸根、氯离子、碳酸根)插层的锌铝水滑石(LDHs),将其作为光催化剂用于可见光催化降解亚甲基蓝(MB)。通过X射线粉末衍射、Fourier红外光谱、热重质谱和紫外–可见漫反射光谱等技术对催化剂的结构和性质进行表征。结果表明:不同阴离子插层的水滑石对MB表现出了不同的光催化活性,其中,碳酸根插层的锌铝水滑石具有较高的光催化活性;在可见光照射180 min后,水滑石材料对MB的降解率从高到低依次为:ZnAl-CO_3 LDHs(95%)、ZnAl-Cl LDHs(70%)、ZnAl-NO_3 LDHs(62%)。此外,进一步探讨了不同阴离子插层的锌铝水滑石可见光催化降解MB的动力学参数和可能的光催化路径。     

水滑石类阴离子型插层材料的结构、性质、制备及其在催化领域的应用

水滑石类(LDHs)化合物是阴离子型插层材料的典型代表,因其具有层板组成的可调变性和层间阴离子的可交换性等特征,使得此类材料在众多领域具有重要的应用价值.本文以LDHs层状化合物在催化领域的应用为背景,综述了LDHs的结构特征及酸碱催化性质,对阴离子插层LDHs的多种制备方法进行了比较和评述,并简要介绍了本课题组在LDHs负载纳米金催化剂方面的工作进展.     

LDHs材料的结构、性质及其应用研究进展

LDHs(layered double hydroxides)是一类具有双金属氢氧化物层结构的新型无机材料,其酸碱性、热稳定性、层间阴离子可交换性以及结构记忆效应等特性在诸多领域中得到了广泛应用,成为当前研究的热点。针对国内外研究现状,本文综述了LDHs材料的基本性质、层间不同种阴离子及插层阴离子的化学作用。在此基础上,概括了LDHs材料的制备、表征方法和相关领域的应用,介绍了其在不同溶剂中进行剥离的研究进展,指出能否将其工业化扩大生产是制约其应用的重要因素,同时也分析了当前需要解决的相关问题,为今后LDHs材料的研究提供借鉴。     

层状复合氢氧化物的结构调控及其吸附重金属离子的研究进展

层状复合氢氧化物（LDHs）是具有特殊层状结构的阴离子黏土,具有化学组成可调、比表面积大及结构记忆效应独特等性质,在废水处理方面备受关注。调控LDHs自身结构,是进一步扩大其应用范围、提高其吸附性能的有效途径。该文介绍了LDHs特殊的层状结构和其自身性质;总结了LDHs最常用的制备方法,即共沉淀法、离子交换法、尿素水解法、煅烧复原法和溶胶-凝胶法等,分别介绍了各种制备方法的原理和特点;综述了LDHs的结构调控对其吸附重金属离子性能的影响,并总结了LDHs对重金属离子的吸附机理;最后,指出了目前LDHs在处理含有重金属离子废水研究中面临的挑战,并对该材料未来的研究方向和发展趋势进行了展望。     

马来酸酐酰化β-环糊精柱撑Zn/Al-CO_3型水滑石的制备及表征

通过酯化反应合成马来酸酐酰化β-环糊精(β-CD),采用成核/晶化隔离法制备了Zn/Al水滑石(LDHs),并以水滑石为前驱体,用返混法进行插层组装合成马来酸酐酰化β-CD柱撑Zn/Al水滑石,利用XRD、FTIR对其结构进行表征。结果表明,利用返混法进行插层组装,可以成功的将马来酸酐酰化β-CD阴离子插入Zn/Al水滑石层间,其层间距由原来的0.76 nm增大为3.43 nm。     

水滑石及其纳米插层材料的制备和应用

概述了水滑石及其纳米插层材料的结构、特性、制备方法与应用,着重对水滑石的多种合成方法如共沉淀法、溶胶-凝胶法、水热合成法和离子交换法等进行了比较和评述,并介绍了不同类别插层材料的应用。最后提出了目前在水滑石基纳米插层材料的制备方法、插入阴离子的稳定性及材料应用等方面存在的问题、发展方向和应用前景等。     

PdMgAl类水滑石的合成与表征

以镁铝硝酸根型LDHs为前体,用离子交换法将Na2[PdCl4]中的PdCl2-4作为客体插入了前体的层间,得到Pd-HLTcs,并采用XRD、FT-IR、DTA以及BET法测定比表面积等测试手段对样品进行表征和分析,探讨了不同组成、晶化温度、晶化时间等因素对类水滑石合成的影响.     

水杨酸根插层Mg-Al水滑石的制备与表征

本文以CO32-型镁铝水滑石为前体,乙二醇为分散介质,用返混沉淀法制备水杨酸根插层水滑石,并用XRD,FT-IR,UV-Vis等手段对样品进行了表征.结果表明,通过改变条件,水杨酸根离子可以引入镁铝水滑石层间,取代层间CO32-,从而得到一种具有屏蔽和吸收紫外能力的有机-无机复合功能材料.     

胭脂红阴离子插层Mg/Al-LDH晶体结构的研究

用液相共沉淀法制备胭脂红插层Mg/Al双氢氧化物,对产物晶化成核以及胭脂红阴离子插层的机理进行探讨,对不同条件下晶化成核LDH的晶体结构、晶面生长选择性和晶粒尺寸等结构参数进行分析比较,得出不同反应条件对晶体形成的影响规律。根据LDH层间距和胭脂红离子的几何尺度,推算出胭脂红阴离子在双氢氧化物层间的配置方式为单层平卧。     

Quaternized polysulfone‐based nanocomposite membranes and improved properties by intercalated layered double hydroxide

Two anions (dodecylbenzenesulfonate anion and stearate anion) are employed to synthesize intercalated layered double hydroxides (LDH) by co‐precipitation method. Then the intercalated LDHs are incorporated in the casting solutions of chloromethylated polysulfone (CMPSF) for fabricating quaternized polysulfone/LDH nanocomposite membranes. Fourier transform infrared, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and mastersizer laser particle size analysis are used to characterize the structure and morphology of LDHs and membranes. The properties of the composite membranes including water uptake, mechanical property, thermal stability, and ionic conductivity are investigated. Compared with other anion exchange membranes, both nanocomposite membranes containing 5% LDH sheets displayed better balanced performance. They exhibit the ionic conductivity of 3.58 × 10^?2 S cm^?1 and 3.86 × 10^?2 S cm^?1 at 60°C, respectively. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers     

A new route to synthesis of sulphonato-salen-chromium(III) hydrotalcites: Highly selective catalysts for oxidation of benzyl alcohol to benzaldehyde

The Mg–Al layered-double hydroxides (LDHs) intercalated by three kinds of sulphonato-salen-chromium(III) complexes were prepared and characterized by FTIR, UV–vis, XRD and elemental analysis. It was found that the homogeneous complexes were successfully intercalated into the LDH interlayer via the method of anion exchange followed by coordination with chromium(III) chloride. And the resulting LDH hosted chromium complexes were shown to be effective heterogeneous catalysts for the solvent-free oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) using 30% H₂O₂ as oxidant. Furthermore, owing to the different local environment of the central metal ion chromium(III), the catalyst with the backbone of o-C₆H₄ displayed the highest catalytic performance followed by the NH(CH₂CH₂)₂ with the (CH₂)₂ showing the lowest BzH yield. In addition, a tentative mechanism was also discussed.     

Exfoliation and dispersion of micrometer-sized LDH particles in poly(ethylene terephthalate) and their nanocomposite thermal stability

Effect of surface modification on exfoliation and dispersion of micrometer-sized layered double hydroxide (LDH) in poly(ethylene terephthalate) (PET) and the thermal stability of the resultant PET/LDH nanocomposites or composite have been studied. First, large micrometer-sized LDH with carbonate anions was prepared by urea hydrolysis method. Then, various anions including nitrate (NO₃⁻), dodecyl sulfate (DS⁻) or dodecyl benzene sulphonate (DBS⁻) were intercalated into the interlayer space via anion exchange reaction. By solution intercalation process, PET/LDH_DS and PET/LDH_DBS nanocomposites were successfully obtained, while the LDH_NO₃ could not be exfoliated enough in the PET matrix. Finally, the thermal stabilities of the PET/LDH nanocomposites or composite were investigated.     

Caprylate intercalated layered double hydroxide as adsorbent of the linuron, 2,4-DB and metamitron pesticides from aqueous solution

This study was carried out to elucidate the synthesis of organo-layer double hydroxide (LDH) and its capacity to adsorbs the widely applied pesticides linuron, 2,4-DB and metamitron from waters. The adsorbent (LDH-Cap) was synthesized by incorporating organic anion caprylate into magnesium aluminum layered double hydroxide with chloride as interlayer anion (LDH-Cl) via ion exchange. Characterization of the LDH-Cap adsorbent was carried out using powder X-ray diffraction (PXRD), infrared spectroscopy (FT-IR) and thermal analyses (TG and DTA). PXRD patterns indicate that caprylate anion was successfully intercalated in LDH according to the basal spacing d₀₀₃ = 19.2 Å. Adsorption results indicated that these three pesticides were adsorbed on LDH-Cap. The high percentage of initial pesticide amounts removed within the first 30 min (~ 90% of the total amount adsorbed) for linuron and 2,4-DB revealed a rapid adsorption process, while it was more gradual for metamitron. PXRD results suggest that adsorbed 2,4-DB and metamitron were intercalated in the LDH interlayers probably between caprylate chains and the brucite layers. Linuron was probably adsorbed on the external particle surface of LDH. Adsorption kinetic study revealed that the adsorption process followed pseudo-second-order equation. Adsorption data were well fitted to the Freundlich isotherm. The desorption of the pesticides from adsorption products were tested with three different solvents (distilled water, ethanol and acetone) and it was partial in all cases.     

Controllable luminescence and electrochemical detection of Pb ion based on the 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonate) dye and dodecanesulfonate co-intercalated layered double hydroxide

2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonate) dye (ABTS) and dodecanesulfonate anion (SDS) have been co-intercalated into the ZnAl-layered double hydroxide (ZnAl LDH) matrix by a hydrothermal co-precipitation method, with obtained samples denoted as ABTS-SDS(x)/LDH (x stands for the molar percentage content of ABTS with respect to total intercalated content). The structure and chemical composition of the as-prepared compounds were characterized by X-ray diffraction (XRD), FT-IR spectra and elemental analysis. Fluorescence spectra demonstrated that the sample with 60% ABTS molar percentage, exhibited the optimal luminescent intensity. The fluorescence lifetime of ABTS in the gallery of LDH was enhanced significantly compared with that of pristine ABTS powder. As well, the ABTS-SDS/LDH thin film fabricated by the solvent evaporation method exhibited a well-defined c-orientation, which can be confirmed by XRD and scanning electron microscopy (SEM). Moreover, the ABTS-SDS(60%)/LDH film showed polarized luminescence (anisotropy: 0.35) and electrochemical response to aqueous solution containing Pb²⁺ ion. These results demonstrate that the ABTS-SDS/LDH system can serve as a good candidate for the solid-sate luminescence and electrochemical sensor materials.     

Layered double hydroxide-like materials: nanocomposites for use in concrete

Nitrobenzoic acid (NBA), naphthalene-2, 6-disulfonic acid (26NS), and naphthalene-2 sulfonic acid (2NS) salts were intercalated into a layered double hydroxide-like host material (LDH). The intercalation process was achieved by anion exchange of nitrates in the host material, Ca₂Al(OH)₆NO₃, nH₂O (CaAl LDH), which was prepared by a coprecipitation technique. The resulting organo derivatives CaAlNBA LDH, CaAl26NS LDH, and CaAl2NS LDH produced a tilted orientation of NBA and 26NS anions in the interlayer space, while 2NS anions induced a perpendicular bilayer arrangement.Materials characterization was carried out using X-ray diffraction (XRD), IR-spectroscopy, thermal analysis, and scanning electron microscopy (SEM). These preliminary results open up a new direction towards the synthesis of nanocomposites using polymeric entities and layered materials for future applications in cement and concrete science, e.g., control of the effect of admixtures on the kinetics of cement hydration by programming their temporal release.     

Preparation and properties of exfoliated nanocomposites through intercalated a photoinitiator into LDH interlayer used for UV curing coatings

The exfoliated polymer/layered double hydroxide (LDH) nanocomposites based on MgAl were prepared through intercalating a photoinitiator into LDH interlayer, following by UV irradiation induced polymerization. The fragmental photoinitiator, 2-hydroxy-2-methyl-1-phenylpropane-1-one (1173) firstly reacted with isophorone diisocyanate (IPDI) to obtain the semiadduct, 1173-IPDI, and then reacted with the LDH modified by aminoundecanoic acid, obtaining LDH-1173 with an intercalated microstructure, which was characterized by FTIR, XRD, and TGA measurements. The obtained LDH-1173 was mixed with the multifunctional acrylate oligomer and monomer, and then exposed to a UV lamp to prepare a polymer/LDH nanocomposite. From the XRD, TEM and HR-TEM analysis, as well the photopolymerization kinetics investigation, it was found that the LDH-1173 effectively initiated the photopolymerization of acrylates, and formed exfoliated polymer/LDH nanocomposites. However, the mostly intercalated polymer/LDH nanocomposites were obtained for the systems with additional 1173 except for LDH-1173 addition. Compared with the pure polymer material, both the exfoliated and intercalated polymer/LDH nanocomposites exhibited the enhancements in mechanical and thermal properties, as well as hardness.     

松香酸根插层剥离型纳米水滑石材料的制备与表征

采用共沉淀法制备了松香酸根插层剥离型纳米水滑石。借助红外光谱、X射线衍射、热分析和高分辨透射电镜等对其进行了表征。结果表明,随着松香酸根插入镁铝水滑石层间,水滑石层间距逐渐增大,最终克服水滑石层板间作用力而将其剥离,形成了剥离型纳米水滑石材料。该材料的热稳定性也得到显著提高,具有潜在的应用价值。