Pentadecatungstotrivanadodiphosphoric heteropoly acid with Dawson structure: Synthesis, conductivity and conductive mechanism

A general strategy in terms of degradating and ion-exchange synthesis was used to design pentadecatungstotrivanadodiphosphoric heteropoly acid H(9)P(2)W(15)V(3)O(62)·28H(2)O with Dawson structure and excellent conductivity. The product was characterized by ICP-MS, IR, UV, XRD, (31)P NMR, TG-DTA and electrochemical impedance spectroscopy (EIS). The results indicate that H(9)P(2)W(15)V(3)O(62)·28H(2)O possesses the Dawson structure. EIS measurements show a high conductivity (3.64 × 10(-2) S cm(-1) at 26 °C and 75% relative humidity), with an activation energy of 31.34 kJ mol(-1) for proton conduction. Its mechanism for proton conduction is the Vehicle mechanism.     

十钨钼钒锗杂多酸复合二氧化硅凝胶的制备与质子导电性

通过溶胶-凝胶法制备了掺杂十钨钼钒锗杂多酸的二氧化硅凝胶,红外光谱证明了凝胶中有Keggin[GeW10MoVO40]5-结构的阴离子存在．在室温(18℃)下,掺十钨钼钒锗酸71％的凝胶的质子电导率为1．97×10-3S·cm-1,它们是好的质子导体．     

银钨硼三元杂多配合物的合成、稀土多元渗及其导电性

用直接法合成了未见文献报道的具有Keggin结构的以Ag作为第二配位离子的钨硼杂多配合物,利用ICP,IR,XRD和XPS等对其结构进行了表征.以Gd作为渗入元素对其进行化学气相扩渗,借助IR,TG-DTA,XPS和XRD对配合物扩渗前后的结构及稳定性进行了对比研究.导电性的测试表明:室温下,扩渗后试样的电导率提高了约103倍,且热稳定性也有所提高,是一种受温度变化影响较小的导电材料,为制备可实用的导电材料提供了一条新途径.     

The proton conductivity of heteropoly compounds

Five kinds of molybdovanadophosphoric acid: H7[P2Mo17VO62], H8[P2Mo16V2O62], H9[P2Mo15V3O62], H8[P2Mo14V4O61(H2O)] and H9[P2Mo13V5O61(H2O)] have been synthesized. The salts, K13[Ln(SiW11O39)2] (Ln=La, Ce, Pr, Nd or Gd) have also been prepared. The proton conductivities (C) of all the above compounds have been measured, and are dependent not only on the nature of compound itself, but also on external factors such as temperature and frequency. The general trend of proton conductivity, changing with the hydration number, frequency and temperature is summarized and important conclusions have been drawn based on experimental measurements. The resulting data have not been reported hitherto in the literature.     

Preparation and conductivity of tungstovanadogermanic heteropoly acid polyethylene glycol (PEG) hybrid material

In this work, the polyethylene glycol (PEG) hybrid material composited with tungstovanadogermanic heteropoly acid was prepared. Infrared (IR) spectrum revealed that the Keggin structure characteristic of the anion was present in PEG hybrid material. At room temperature (20°C), the conductivity of the sample is 4.07×10⁻³ S cm⁻¹. The results indicated that it is a new kind of excellent high-proton conductor. According to the experimental results, we proposed a possible mechanism of the proton conduction of the hybrid materials.     

碱土金属钨铬杂多配合物的合成、表征及热稳定性研究

用直接法合成了以Cr为中心原子的碱土金属和W的三元杂多配合物,经ICP和TG曲线确定其化学式为K7[CrA(H2O)W11O39].xH2O(A=Mg2 ,Ca2 ,Sr2 和Ba2 ),采用IR,UV,XRD,XPS和183W NMR等手段对配合物结构进行了表征,确认所合成的配合物为-αKeggin结构.借助TG-DTA详细讨论了配合物的热稳定性,得出合成配合物的热稳定温度为450℃左右.     

Hydration and acetoxylation of dihydromyrcene catalyzed by heteropoly acid

The liquid-phase hydration and acetoxylation of the monoterpene dihydromyrcene (DHM, 3,7-dimethyl-1,6-octadiene) are efficiently catalyzed by Keggin-type heteropoly acid H₃PW₁₂O₄₀ (HPA) at 14–30°C to yield dihydromyrcenol (DHM---OH, 2,6-dimethyl-7-octen-2-ol) and dihydromyrcenyl acetate (DHM---OAc). Homogeneous, biphasic (DHM/AcOH-H₂O-HPA) and heterogeneous (with HPA/SiO₂ catalyst) reactions have been studied. HPA has a much higher catalytic activity than conventional acid catalysts such as H₂SO₄ and Amberlyst-15. A synthetically useful biphasic acetoxylation/hydration of DHM has been developed. The method provides a 90% selectivity to the sum of DHM---OH and DHM---OAc at 21% DHM conversion and allows for easy and clean catalyst recycling without loss of activity.     

Keggin型P-Mo-V杂多酸的合成

杂多化合物(Ｈｅｔｅｒｏｐｏｌｙｃｏｍｐｏｕｎｄ,简写为ＨＰＣ)的结构、性质特殊:化学计量的ＨＰＣ组成简单、结构确定,既有配合物和金属氧化物的结构特征,又有酸性和氧化还原性质,多数在水和含氧有机溶剂中溶解度甚大,而且相当稳定,固态ＨＰＣ的热稳定性也较好,广泛用于催化领域,在医学领域特别是抗癌及抗病毒领域也有较好的应用前景[1]。具有Ｋｅｇｇｉｎ结构的ＨＰＣ具有三级结构,其一级结构为杂多阴离子(Ｈｅｔｅｒｏｐｏｌｙａｎｉｏｎ,简写成ＨＰＡＮ),表达通式为[ＸＭ12Ｏ40]ｎ-8(ｎ为元素Ｘ的氧化数),结构描述以[ＸＯ4]四面…     

甘氨酸的杂多酸超分子化合物的合成及性质研究

首次合成了甘氨酸的Keggin结构杂多酸超分子化合物(HGly)3[PW12O40]·5H2O(HGly)4[SiW12O40]·4H2O,用元素分析,IR,UV,TG-DTA,XRD和NMR等方法对标题化合物进行了表征,并讨论了它们的合成条件及结构特性.     

甘氨酸的杂多酚超分子化合物的合成及性质研究

首次合成了甘氨酸的Ｋｅｇｇｉｎ结构杂多酸超分子化合物（ＨＧｌｙ）３「ＰＷ１２Ｏ４０」．５Ｈ２Ｏ（ＨＧｌｙ）４「ＳｉＷ１２Ｏ４０」．４Ｈ２Ｏ,用元素分析,ＩＲ,ＵＶ,ＴＧ－ＤＴＡ,ＸＲＤ和ＮＭＲ等方法对标题化合物进行了表征,并讨论了它们的合成条件及结构特性。     

硅烷偶联剂改性SBA-15固载Keggin型杂多酸催化合成柠檬酸三丁酯

以3-(甲基丙烯酰氧)丙基三甲氧基硅烷(MEMO)表面改性的介孔分子筛SBA-15为载体,制备了一系列介孔分子筛/硅烷偶联剂@杂多酸复合催化剂SBA-15/MEMO@HnXW12O40(X=P⁵+,Si⁴⁺,B³⁺;n=3,4,5),并利用FTIR、P-XRD、TEM、N2吸附-脱附对其结构进行表征。以SBA-15/MEMO@HnXW12O40(X=P⁵⁺,Si⁴⁺,B³⁺;n=3,4,5)为负载型杂多酸催化剂对柠檬酸三丁酯的催化合成进行研究,分别考察了酸醇摩尔比、催化剂用量、反应温度、反应时间对催化合成柠檬酸三丁酯酯化率的影响,并获得合成柠檬酸三丁酯的最佳工艺条件。结果表明:当负载型硅钨酸催化剂的负载量为50%、催化剂用量为3.8%、酸醇摩尔比为1∶4、反应温度为140℃、反应时间为6 h、环己烷用量为5 mL时酯化率可达97.56%,重复使用7次后酯化率仍可达62.67%。     

Solid polymer electrochemical capacitors using heteropoly acid electrolytes

An electrochemical capacitor utilizing a polyvinyl alcohol (PVA) and H₄SiW₁₂O₄₀ (SiWA) solid polymer electrolyte was developed. The electrolyte was deposited via precursor solution coating followed by thermal pressing and exhibited an ionic conductivity of 0.01 S/cm. The electrolyte has also shown good stability and cycle life. The performance of the solid polymer electrolyte-based capacitor was characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and was compared to a similar capacitor with an aqueous electrolyte.     

Potentiometric determination of water-soluble organic amides using tungstophosphoric heteropoly acid

A procedure is based on the potentiometric titration of water-soluble nitrogen-containing organic compounds with tungstophosphoric acid in an HCl solution using a polarized platinum microelectrode. The analytical range is between 0.4 and 65%. The presence of isobutanol and LiCl in industrial solutions has no effect on determination in a wide concentration range and allows the procedure to be used in the production of some synthetic fibers.     

Synthesis,properties and crystal structure of a heteropoly compound containing titanium

K4H2CoW12O40·2TiO2·9H2O crystallizes from an aqueous solution of Na2WO4, Co(OAc)2 and Ti(SO4)2. The compound has very similar i.r. and u.v. spectra to those of [CoW12O40]6– and [CoW11TiO40]8– but its polarographic behaviour is different from that of [CoW11TiO40]8– and exhibits only reduction of tungsten(VI). A single crystal structural analysis indicates that this compound consists of the heteropolyanion [CoW12O40]6–, titanium–oxygen chain, potassium ions and water molecules.     

钕锗钼杂多酸根配合物的合成、晶体结构和光谱性质

合成及制备了K~7H~6[Nd(GeMo~1~1O~3~9)~2].27H~2O单晶, 测定其晶体结构, 空间群属P2~1/n, 晶胞参数: a=1.7095(4), b=2.6895(3), c=2.1214(5)nm, β=103.11(2)^o; V=9.4994(3)nm^3; Z=4; D~m=3.14g/cm^3, D~c=3.05g/cm^3; μ(MoKa)=43.7cm^-^1。利用结构分析的结果, 研究配合物的IR光谱性质, 提出利用IR光谱推测杂多配合物分子结构特征的实验证据和理论根据。电子光谱证实配合物中Nd^3^+的f轨道参与成键。     

Assembly of heteropoly acid nanoparticles in SBA-15 and its performance as an acid catalyst

Keggin‐type 12‐tungstophosphoric acid (TPA) nanocrystals have been assembled inside the pores of mesoporous silica through a vacuum impregnation method by using large‐pore SBA‐15 as a nanoreactor. The product was characterized by Brunauer–Emmet–Teller particle size distribution (BET‐PSD), NMR and FT‐IR spectroscopy, X‐ray diffraction (XRD), tranmsission electron microscopy (TEM), differential thermal analysis (DTA) and FT‐IR of adsorbed pyridine. The experimental results illustrate that the TPA nanocrystals are excellent Brønsted acid catalytic materials at room temperature.     

Synthesis of hexamethylene-1,6-dicarbamate by methoxycarbonylation of 1,6-hexamethylene diamine with dimethyl carbonate over bulk and hybrid heteropoly acid catalyst

Synthesis of HDC by methoxycarbonylation of HDA with DMC was carried out over the bulk and hybrid heteropoly acid (HPA) catalyst. The catalysts were systematically characterized by XRD, FTIR, SEM and NH₃-TPD techniques. The by-products produced in the reaction were identified and a possible reaction pathway was proposed based on the by-products analysis. The performances of bulk and hybrid HPA catalysts were evaluated. The H₄[SiW₁₂O₄₀] catalyst revealed high performance compared with other catalysts and its high performance was attributed to its acidic properties. Effects of reaction parameters and reusability of the H₄[SiW₁₂O₄₀] catalyst were also investigated. Under the optimized reaction conditions, HDA conversion reached 93.2% with 64.8% HDC selectivity and only 3.8% by-product selectivity. Moreover, a possible reaction mechanism was proposed for the synthesis of HDC over H₄[SiW₁₂O₄₀] catalyst.