（TEAH）nH3-nPW12O40催化苯甲醇选择氧化及其反应机理

以Keggin结构的磷钨酸和三乙胺（TEA）为原料,通过简单的酸碱反应合成了磷钨酸的TEA盐.并以它们为催化剂,考察了以H₂O₂为氧化剂、以水为溶剂的体系中苯甲醇选择氧化制备苯甲醛的反应性能.结果表明,（TEAH）_nH_3-nPW₁₂O₄₀（n=1,2,3）系列催化剂对苯甲醇的选择氧化反应有很高的活性和选择性,且可被分离和循环使用.在适宜的反应条件下,最佳催化剂（TEAH）H₂PW₁₂O₄₀上,苯甲醇的转化率可达99.6%,苯甲醛的选择性为100%.还采用IR,³¹PNMR谱和元素分析技术,对催化剂和反应过程中催化剂物种的转化和分布进行了考察,进而导出了反应机理.在这个水--油两相反应中,（PW₁₂O₄₀）^3-首先在H₂O₂的作用下,氧化降解为溶于水的小分子过氧物种（PO₄（WO（O₂）₂）₄）^3-和自由W物种.（PO₄（WO（O₂）₂）₄）^3-是真正的活性物种,可将部份溶于水层的苯甲醇氧化为苯甲醛,自身转变为失去活性氧的反应后物种（SAR）.而SAR又可与自由W物种一起聚合为前驱体状态的（PW₁₂O₄₀）^3-,完成催化循环.     

四种Keggin型多酸纳米材料的制备及其吸附有机染料的性能

以4种Keggin型多酸作为原料(分别为H₃PW₁₂O₄₀·36H₂O(简写为PW₁₂^a)、H₃PMo₁₂O₄₀·34H₂O(简写为PMo₁₂^a)、H₄SiW₁₂O₄₀·35H₂O(简写为SiW₁₂^a)和H₄GeW₁₂O₄₀·40H₂O(简写为GeW₁₂^a)),采用表面活性剂智能化控制的软化学法制备了相应的4种Keggin型多酸纳米材料,分别为Ag₃PW₁₂O₄₀·36H₂O(简写为PW₁₂^b)、Ag₃PMo₁₂O₄₀·34H₂O(简写为PMo₁₂^b)、Ag₄SiW₁₂O₄₀·35H₂O(简写为SiW₁₂^b)和Ag₄GeW₁₂O₄₀·40H₂O(简写为GeW₁₂^b)。采用IR、UV-Vis、XRD和SEM表征多酸的结构和纳米粒子的形貌。在室内黑暗条件下,100 mg样品可在5 min内把20 mg·L^-1的100 mL亚甲基蓝(MB)染料溶液脱色,使其变为接近无色,吸附效率最高可达96.3%,吸附效率大小为PMo₁₂^b > PW₁₂^b > GeW₁₂^b > SiW₁₂^b。相同条件下,100 mg样品使20 mg·L^-1的100 mL罗丹明B(RhB)染料溶液30 min内脱色完全,脱色效率最高可达96.1%,吸附效率大小为PW₁₂^b > PMo₁₂^b > SiW₁₂^b > GeW₁₂^b。说明该4种多酸纳米材料具有较高的吸附有机染料性能。     

含磷钼酸及2,2’-联吡啶-3,3’-二羧酸配体的铜配位聚合物的合成、晶体结构与电化学性质

在水热条件下合成了一个新的化合物{[Cu₄(PMo₁₂O₄₀)(H₂O)₅(H₂bpdc)(Hbpdc)(bpdc)₂]·6H₂O}_n(H₂bpdc=2, 2’-联吡啶-3, 3’-二羧酸), 并用元素分析、IR、TG和X-射线衍射等手段进行了表征。结果表明本化合物的晶体结构中, 最小不对称单元包含1个 [Cu₄(H₂O)₅(H₂bpdc)(Hbpdc)(bpdc)₂]³⁺阳离子, 1个[PMo₁₂O₄₀]^3-阴离子和6个结晶水分子。Cu(Ⅱ)与相邻[PMo₁₂O₄₀]^3-的桥氧原子配位, 形成一维链状结构。电化学研究表明, 化合物存在三步氧化还原过程。     

四种Keggin型多酸纳米材料的制备及其吸附有机染料的性能

以4种Keggin型多酸作为原料(分别为H₃PW₁₂O₄₀·36H₂O(简写为PW₁₂^a)、H₃PMo₁₂O₄₀·34H₂O(简写为PMo₁₂^a)、H₄SiW₁₂O₄₀·35H₂O(简写为SiW₁₂^a)和H₄GeW₁₂O₄₀·40H₂O(简写为GeW₁₂^a)),采用表面活性剂智能化控制的软化学法制备了相应的4种Keggin型多酸纳米材料,分别为Ag₃PW₁₂O₄₀·36H₂O(简写为PW₁₂^b)、Ag₃PMo₁₂O₄₀·34H₂O(简写为PMo₁₂^b)、Ag₄SiW₁₂O₄₀·35H₂O(简写为SiW₁₂^b)和Ag₄GeW₁₂O₄₀·40H₂O(简写为GeW₁₂^b)。采用IR、UV-Vis、XRD和SEM表征多酸的结构和纳米粒子的形貌。在室内黑暗条件下,100mg样品可在5min内把20mg·L^-1的100mL亚甲基蓝(MB)染料溶液脱色,使其变为接近无色,吸附效率最高可达96.3%,吸附效率大小为PMo₁₂^b >PW₁₂^b >GeW₁₂^b >SiW₁₂^b。相同条件下,100mg样品使20mg·L^-1的100mL罗丹明B(RhB)染料溶液30min内脱色完全,脱色效率最高可达96.1%,吸附效率大小为PW₁₂^b >PMo₁₂^b >SiW₁₂^b >GeW₁₂^b。说明该4种多酸纳米材料具有较高的吸附有机染料性能。     

三核钨簇合物-V2O5催化剂对苯乙烯氧化反应的催化

本文研究了三核钨簇合物［W₃O₂(CH₃CO₂)₆(H₂O)₃］Br₃·2H₂O与一些物质组成的二元催化剂对苯乙烯氧化反应的催化作用,结果表明：钨簇合物-V₂O₅催化剂对苯乙烯氧化反应的催化效果特别显著,而且在反应前后其重量、结构及催化活性基本不变,可以多次回收重复使用。对影响钨簇合物-V₂O₅催化剂催化性能的几个因素进行了讨论,测定了催化剂及其吸附氧气的红外光谱,说明钨簇合物及V₂O₅可以与O₂形成分子氧配合物及超氧(O^-₂)配合物。     

二苯基四硫富瓦烯-十二钨杂多酸自由基盐的合成、性质和结构

用电结晶法合成了二苯基四硫富瓦烯(DBTTF)-十二钨杂多酸自由基盐，(DBTTF)₆HSiW₁₂O₄₀·2H₂O和(DBTTF)₆PW₁₂O₄₀·5H₂O，并用红外光谱、电子光谱和ESR谱进行了表征。测定了两个盐的磁化率、电导率和(DBTTF)₆HSiW₁₂O₄₀·2H₂O的单晶结构以及X-射线粉末衍射图。晶体属三斜晶系，P1空间群；晶胞参数为：a=13.774(2)?, b=14.196(2)?, c=15.628(3)?, α=104.48(1)°, β=103.97(1)°, γ=95.82(1)°, V=2828.4(8)?³, Z=1, Dc=2.789 mg/m³, R=0.0615。两种盐均为顺磁性物质，具有半导体的电传导性。     

层状钨基氧化物复合材料的合成与电子特性

W₂O₆·H₂O /一元烷基胺复合物[(C_nH_2n+1NH₂，n=4、8、12、16)嵌入层状氧化钨W₂O₆·H₂O] 的XRD、IR、TG-DSC分析表明：烷基胺C_nH_2n+1NH₂能基于质子加合的机制嵌入W₂O₆·H₂O层间，且插层复合物之间烷基胺的插入与抽出是个可逆过程；烷基胺嵌入层间后以全反式构象双层排布，层间距d随烷基胺碳原子数的增加而线性增长，烷基链与层板的夹角为71.6°。插层复合物UV-Vis分析发现，各种复合物的禁带宽度相对半导体氧化钨的禁带宽度变宽了很多，这表明可以通过嵌入不同的物质来调节氧化钨层与层之间的电子传递能力。     

制备参数对高比表面积介孔催化剂La-Co-Zr-O结构与性能的影响

采用双表面活性剂模板(十六烷基三甲基溴化铵和聚乙二醇辛基苯基醚的混合物)分解法制备了不同原子比(n_La+n_Co)/(n_La+n_Co+n_Zr)和不同温度焙烧的系列介孔混合氧化物催化剂La-Co-Zr-O。运用XRD、N₂吸附/脱附、XPS和H₂-TPR等技术对催化剂进行了表征，并以CO和C₃H₈氧化为模型反应，考察了组分配比和焙烧温度等参数对催化剂催化性能的影响。比表面积和孔径测试结果表明，样品具有很高的比表面积(108～266 m²·g^-1)和分布集中的孔径(3.4～3.9 nm)，Zr含量较高的样品比表面积较大。XRD结果表明，样品中的活性组分钴物种主要以Co₃O₄形式存在；XPS和H₂-TPR结果表明，样品中可还原的晶格氧的数量、活动度以及表面钴原子浓度均与催化剂对CO和C₃H₈的氧化性能密切相关。原子比为0.5的样品中，较多的晶格氧易于在相对低温下还原；而原子比为0.7的样品表面钴原子浓度较高，这使得两样品均表现出较高的催化活性。经650 ℃焙烧的样品仍保持较高的比表面积(108 m²·g^-1)和分布集中的介孔孔径(最可几孔径约3.8 nm)，且催化活性下降幅度也很小，表明该系列介孔催化剂具有优良的抗烧结能力和介孔热稳定性。     

Criegee自由基CH2O2与H2O反应机理及动力学的理论研究

在6-311＋G(2d,2p)水平下, 采用密度泛函理论(DFT)的B3LYP方法, 研究了Criegee 自由基CH₂O₂与H₂O的反应. 结果表明反应存在三个通道: CH₂O₂＋H₂O®HOCH₂OOH (R1); CH₂O₂＋H₂O®HCO＋OH＋H₂O (R2); CH₂O₂＋H₂O®HCHO＋H₂O₂ (R3), 各通道的势垒高度分别为43.35, 85.30和125.85 kJ/mol. 298 K下主反应通道(R1)的经典过渡态理论(TST)与变分过渡态理论(CVT)的速率常数k^TST与k^CVT均为2.47×10^－17 cm³•molecule^－1•s^－1, 而经小曲率隧道效应模型(SCT)校正后的速率常数k^CVT/SCT为 5.22×10^－17 cm³•molecule^－1•s^－1. 另外, 还给出了200～2000 K 温度范围内拟合得到的速率常数随温度变化的三参数Arrhenius方程.     

水热法合成多金属氧酸盐棒状超细晶体

以SrCl₂·6H₂O、(NH₄)₆P₂Mo₁₈O₆₂·nH₂O为原料，在PEG-600/H₂O微乳体系中于80～130 ℃温度下水热反应8～12 h，从而制得一种多金属氧酸盐棒状超细晶体，组成是Sr₃P₂Mo₁₈O₆₂·nH₂O。该超细晶体具有长棒状形貌、高结晶度且分散性能较好，长度范围在10.0～20.0 μm，径度在1.0～2.0 μm。对反应体系中的PEG-600/H₂O体积比(V_PEC-600∶V_H2O)、水热温度以及(NH₄)₆P₂Mo₁₈O₆₂·nH₂O/SrCl₂·6H₂O质量比(W_POMs∶W_SrCl2·6H2O)3个影响因素进行了探讨，结果表明：V_PEC-600∶V_H2O主要对棒状超细晶体的形貌、长径比以及晶体结晶度有着重要影响，体积比在范围V_PEC-600∶V_H2O=(1.50～2.00)∶1.00有利于大长径比的棒状超细晶体的形成；水热温度则优选80～130 ℃范围，过低则不发生反应，过高则发生了多金属氧酸盐与PEG-600的氧化-还原反应；W_POMs∶W_SrCl2·6H2O基本上不影响超细晶体的形成。还初步探讨了该棒状超细晶体的形成机理。     

Kinetics of the synthesis of propyl and butyl acrylates in the presence of some heteropolyacids as catalysts

Esterification reactions of acrylic acid with n‐propanol and n‐butanol were carried out in the liquid phase in the presence of H₃PW₁₂O₄₀ or H₃PMo₁₂O₄₀ as a catalyst, at various temperatures, molar ratios of the reactants, and concentrations of the catalyst. The kinetic equations had a nonelementary form. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 12–17, 2009     

Transition metal substituted tungstophosphoric compound catalyzed oxidation of hexanol to hexanal with hydrogen peroxide

Summary The oxidation of hexanol in the presence of the Keggin-type heteropoly compounds (HPCs) H₃PMo_nW_12-nO₄₀ (denoted as PMo_nW_12-n, n=0,1) and Na₅PW₁₁ZO₃₉ (denoted as PW₁₁Z, Z = Mn, Fe, Co, Ni, Cu and Zn) was carried out to produce hexanal and hexanoic acid. The reaction was conducted in tert-butanol (t-BuOH), using cetylpyridinium bromide (CPB) salts of HPA and 15% aqueous H₂O₂ as oxidant under mild condition. The PMoW₁₁ catalyst showed higher hexanol conversion of 25%, the lowest selectivity to hexanal of 64.4% and an efficient utilization of H₂O₂ of 34%. Over the transition metal substituted PW₁₁Z catalysts decomposition of H₂O₂ was rapid. For these PW₁₁Z catalysts, the efficient utilization of H₂O₂ decreased to 9% or even lower. By means of IR, UV-visible and GC-MS techniques the catalysts were characterized.     

pH-dependent assembly of saturated to dilacunary Keggin-based silicotungstate: [Cu(en)2(H2O)][H2en]{γ-SiW10O36[Cu(en)2(H2O)]2}·7.5H2O

By controlling the pH of the reaction system, a dilacunary γ-Keggin silicotungstate [Cu(en)₂(H₂O)][H₂en]{γ-SiW₁₀O₃₆[Cu(en)₂(H₂O)]₂}·7.5H₂O (1) (en?=?ethylenediamine) has been hydrothermally synthesized by the reaction of CuCl₂ with α-H₄SiW₁₂O₄₀ and characterized by IR spectra, thermogravimetric analysis, and single-crystal X-ray diffraction. The product is prepared in the pH range 7.9–8.2, which reveals that pH plays a key role in the assembly of saturated α-H₄SiW₁₂O₄₀ to dilacunary [γ-SiW₁₀O₃₆]^8? polyoxometalate. The polyoxoanion {γ-SiW₁₀O₃₆[Cu(en)₂(H₂O)]₂]}^4? of 1 presents a rare [γ-SiW₁₀O₃₆]^8?-retaining structure, in which two lacunary sites of [γ-SiW₁₀O₃₆]^8? are unoccupied, meanwhile, two [Cu(en)₂(H₂O)]²⁺ groups are grafted on either side of the [γ-SiW₁₀O₃₆]^8? unit by Cu–O–W bond.     

Acetylation of Alcohols Catalyzed by Dodeca-tungsto(molybdo)phosphoric acid

Summary. Acetylation of primary, secondary, and tertiary alcohols was carried out in some refluxing alkyl acetates and in two carboxylic acids with the participation of catalytic amounts of H₃PW₁₂O₄₀, H₃PMo₁₂O₄₀, and H₁₄P₅W₃₀O₁₁₀ with good yields and high stereo(regio)specificity under mild reaction condition. H₃PW₁₂O₄₀ and H₃PMo₁₂O₄₀ have also shown excellent reactivity in the formylation of 1-butanol with ethyl formate at room temperature and in short reaction times. Heteropolyacid catalysts could be separated after a simple work up and reused for several times.     

A Simple Polyoxometallate for Selective Oxidation of Benzyl Alcohol to Benzaldehyde with Hydrogen Peroxide

A series of Keggin‐type polyoxometallates, M₃(PW₁₂O₄₀)₂ [M=Ni, Zn, Co, Mn, Cu], FePW₁₂O₄₀, Ni₃(PMo₁₂O₄₀)₂ and Ni₂SiW₁₂O₄₀, were prepared and used as catalysts for selective oxidation of benzyl alcohol into benzaldehyde with H₂O₂ as an oxidant under solvent‐free condition. Ni₃(PW₁₂O₄₀)₂·26H₂O afforded high catalytic activity with TON of 550.6 mol/(mol cat.) and 87.3% selectivity. However, this catalyst can be easily recovered and reused.     

Platinized-heteropolycompound-based nanostructured catalysts for low-temperature hydrogen-air fuel cells

Heteropoly acids Cs _x H_{3 − x} PW₁₂O₄₀ · nH₂O with different cesium content are synthesized as nanostructured compositions. Their actual composition and specific surface are determined, microstructure studied and proton conductivity measured. Composite electrocatalytic systems based on platinized cesium salt of phosphorus-tungsten heteropolyacid Cs_2.3H_0.7PW₁₂O₄₀ · nH₂O are prepared with admixture of Vulcan XC-72 carbon black. Mixed electronic-ionic conduction of the composite systems with different carbon black content is studied. Platinum-based nanostructured electrocatalyst based on the Cs_2.3H_0.7PW₁₂O₄₀ · nH₂O-materials as support is synthesized and studied. The possible effective using of the studied nanocomposite as electrode for low-temperature hydrogen-air fuel cells is demonstrated. Electrochemical studies of catalytic properties of the Pt-Cs_2.3H_0.7PW₁₂O₄₀ · nH₂O-C-electrodes in hydrogen and air are carried out by example of the prepared materials with different carbon black content.     

Cationic ring-opening polymerization of tetrahydrofuran with Keggin-type heteropolycompounds as solid acid catalysts

<正>Three Keggin-type heteropolyanions,namely H_3PMo_(12)O_(40)·13H_2O,(NH_4)_3PMo_(12)O_(40)·4H_2O and H_3PW_(12)O_(40)·13H_2O were prepared and tested in the ring-opening polymerization reaction of tetrahydrofuran.The effects of the counter-cation (H~+,NH_4~+) and the peripheral atoms(Mo,W) on the polymerization were investigated.It has been found that when the protons of H_3PMo_(12)O_(40)·13H_2O were replaced by the ammonium cations the polymerization rate decreased dramatically. Whereas,when the peripheral atoms(Mo) were replaced by their homologous(W),the polymerization rate increased twofold.As for the viscosity average molecular weight(M_v) of polymer products,it was found that the high molecular weight(7930) was obtained by using H_3PW_(12)O_(40)·13H_2O.The molecular weight(M_v) obtained by H_3PMo_(12)O_(40)·13H_2O and (NH_4)_3PMo_(12)O_(40)·4H_2O was 6470 and 6810,respectively.     

A Study of the Acid Properties of Structurally and Compositionally Different Heteropoly Acids in Acetic Acid

The acid properties of heteropoly acids of the following three structure types were studied by conductometry in acetic acid: Keggin (H₃PW₁₂O₄₀, H₃PMo₁₂O₄₀, H₄SiW₁₂O₄₀, H₃PW₁₁ThO₃₉; and H₅PW₁₁XO₄₀, where X(IV) = Ti or Zr), Dawson (-H₆P₂W₁₈O₆₂and -H₆P₂Mo₁₈O₆₂), and H₆P₂W₂₁O₇₁(H₂O)₃. These compounds are electrolytes that dissociate in only the first step of this solvent. The thermodynamic dissociation constants of the heteropoly acids were calculated by the Fuoss–Kraus method. The Hammett acidity functions H ₀of the solutions of H₅PW₁₁XO₄₀, H₃PW₁₂O₄₀, H₄SiW₁₂O₄₀, and H₆P₂W₂₁O₇₁(H₂O)₃in 85% acetic acid at 25°C were determined by the indicator method. All of the test heteropoly acids were found to be strong acids.     

Effect of the Composition and Morphology of the Active Phase of NiMoW/P-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Catalysts with Different Mo/W Ratios on Their Activity in the Reactions of Dibenzothiophene Hydrogenolysis and Naphthalene Hydrogenation

A series of catalysts have been synthesized Ni–Mo–W/P-Al₂O₃ with different Mo: W ratios (a sample without W, Mo: W = 2: 1, Mo: W = 1: 1, Mo: W = 1: 2, and a sample without Мо) and a concentration of P₂O₅ in a support of 0.5 wt %. Heteropoly acids H₃PMo₁₂O₄₀ · nH₂O and H₃PW₁₂O₄₀ · nH₂O and nickel citrate were precursors of the active phase. High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were used to study the surface of the sulfide phase of the samples. Their catalytic activity was estimated in the reactions of dibenzothiophene hydrodesulfurization and naphthalene hydrogenation. A catalyst with the ratio Mo: W = 1: 1 showed the highest activity, and was characterized by the maximum concentration of atomic groups Ni–Mo–W–S, Mo–S, and W–S.     

Esterification of n-Butanol with Acetic Acid in the Presence of Heteropoly Acids with Different Structures and Compositions

The esterification reaction of n-butanol with acetic acid ([BuOH] : [HOAc] = 1 : 15 mol/mol; 55°C, 5% H₂O) was studied in the presence of tungsten heteropoly acids of the Keggin (H₃PW₁₂O₄₀, H₄SiW₁₂O₄₀, H₅PW₁₁TiO₄₀, H₅PW₁₁ZrO₄₀, and H₃PW₁₁ThO₃₉) and Dawson structure (-H₆P₂W₁₈O₆₂, H₆P₂W₂₁O₇₁(H₂O)₃, H₆As₂W₂₁O₆₉(H₂O), and H₂₁B₃W₃₉O₁₃₂). The reaction orders with respect to H₆P₂W₂₁O₇₁(H₂O)₃, H₃PW₁₂O₄₀, and H₆P₂W₁₈O₆₉are equal to 0.78, 1.00, and 0.97, respectively. It was found that the reaction rate depends on the acidity, as well as on the structure and composition of heteropoly acids. The H₂₁B₃W₃₉O₁₃₂heteropoly acid is most active, whereas the Keggin-structure heteropoly acids exhibit the lowest activities. Of the Keggin structure heteropoly acids, H₅PW₁₁ZrO₄₀exhibits the highest activity because of the presence of a Lewis acid site in its structure.