双磺酸基功能化酸性离子液体高效催化甘油醚化

合成具有双磺酸基功能化离子液体[BS2 DABCO][HSO4]2用于甘油与叔丁醇(TBA)醚化反应中,显示出良好的催化活性.采用红外光谱和热重分析对其进行了物理表征,详细考察了反应时间、温度、催化剂用量与甘油/叔丁醇物质的量之比等因素对甘油转化率及单叔丁基甘油醚选择性的影响,得出最佳反应条件.当反应时间为6 h,温度...     

负载型磷钨酸催化剂的制备及催化合成ＥＴＢＥ的性能研究

采用水热法合成纯硅介孔分子筛Si-MCM-41, 并用浸渍法将磷钨酸(PWA)负载到介孔分子筛Si-MCM-41上, 制得了磷钨酸负载量不同的催化剂x%PWA/MCM-41. 利用XRD, FT-IR, Py-IR, BET, TEM对载体和催化剂进行分析. 结果表明, 负载后的PWA颗粒粒径明显减小, 粒径约为10个纳米, PWA在载体表面实现了均匀分布, 通过叔丁醇和乙醇在高压反应釜内生成乙基叔丁基醚的反应测试催化剂的催化性能. 结果表明, 负载型催化剂和纯PWA相比, 前者使叔丁醇(TBA)的转化率、ETBE的选择性有很大提高, 当磷钨酸负载量为30%时TBA的转化率最大. 最优的催化剂制备及反应条件是: 载体550 ℃煅烧脱模, PWA负载量为30%, 催化剂煅烧温度为300 ℃, 醚化反应温度为120 ℃, 乙醇与叔丁醇的摩尔比为2∶ 1, 催化剂的用量为1.4 g.     

微波辐射合成4,4′,4″-三硝基三苯胺

以对硝基苯胺(1)和4-氯硝基苯(2)为原料,二甲基亚砜为溶剂,叔丁醇钾为缚酸剂,氟化钾和四甲基氯化铵为催化剂,在微波辐射下合成了4,4′,4″-三硝基三苯胺(3),其结构经IR表征.正交实验确定最佳反应条件为:13 mmol,n(1)∶n(2)∶n(叔丁醇钾)=1∶3∶2,在125 W下,于130℃反应30 min,3的收率达98.2%.     

SO2-4/SnO2催化剂的制备及其对苯硝化反应的催化活性

采用(NH4)2SO4溶液浸渍法制备了一系列SO2-4/SnO2催化剂(Cat-n,n=5,10,15,20),其结构经IR表征.以Cat-10(焙烧温度500℃)催化苯液相硝化反应的研究结果表明,引入SO2-4后催化剂的活性显著增加,硝基苯产率63.8%.     

高岭土负载SO2-4/ZrO2-TiO2催化剂的制备及其在缩酮合成中的应用

以经H2SO4处理焙烧的高岭土为载体,制备了以其负载的SO4(2-)/ZrO2-TiO2固体酸催化剂.用FT-IR、XRD和NH3-TPD等测试技术表征了催化剂的微观结构及酸强度,考察了对环己酮乙二醇缩酮反应的催化活性及稳定性.结果表明,酸化处理使高岭土表面酸量增加,但酸强度变化不大,而其负载SO4(2-)/ZrO2-TiO2后,经500℃焙烧3 h其酸量及酸强度显著升高.环己酮用量为0.2 mol、乙二醇0.24 mol、催化剂1.2 g、带水剂环己烷15 mL,回流反应70 min后,缩酮收率可达96.8%,催化剂重复使用5次收率保持在90%以上.     

甲烷脱氢芳构化W/HZSM-5基催化剂的制备

由H2SO4酸化的(NH4)2WO4溶液(pH=2～3)制备的W-H2SO4/HZSM-5催化剂对甲烷脱氢芳构化(DHAM)反应的催化活性比不经酸化的(NH4)2WO4溶液(pH=8～9)制备的W/HZSM-5催化剂高得多.氧化前驱态催化剂的H2-TPR研究表明,W-H2SO4/HZSM-5试样的还原所需温度比W/HZSM-5低得多;前者可还原至较低价态的W物种在负载总W量中所占比例也比后者高得多.H2-TPR及相关体系的EPR和Raman表征结果相互佐证表明,用H2SO4酸化导致负载钨酸铵前驱溶液中一些由共边正八面体配位结构单元(WO6)n-构成的聚钨酸根物种的生成;W-H2SO4/HZSM-5催化剂对DHAM反应催化活性之所以高,主要由于所负载的W前驱物种较大部分是(WO6)n-基的W物种,而非(WO4)2-基W物种;在较低温度下就可被还原,且在DHAM反应条件下有一部分可还原至较低价态W4+的(WO6)n-物种很可能是催化活性位的前驱组成部分.     

给电子体在制备烯烃聚合NdCl_3载体催化剂中的作用

<正> Martin以无水稀土氯化物为载体,与磷酸三丁酯(TBP)在庚烷溶剂中反应制得LnCl_3/TBP/TiCl_4载体催化剂,其中以NdCl_3为载体的催化剂对乙烯聚合有很高活性,但对TBP的作用和载钛结构涉及较少。NdCl_3为链状晶体结构,不同于层状晶体结构的MgCl_2和TiCl_3(α和δ型)。我们对NdCl_3/EtOH/TiCl_4催化剂进行了较为详细的研究,并与MgCl_2/EtOH/TiCl_4催化剂进行比较,发现NdCl_3载体催化剂与MgCl_2载体     

焙烧温度对SO42-改性锆交联粘土固体酸结构与催化活性的影响

用聚羟基锆离子交换Na基膨润土中的水合钠离子,再引入SO4^2-,在不同温度焙烧制备了锆交联粘土固体酸催化剂,利用XRD,IR,DTA等手段,对该催化剂的结构进行了分析测试,并以柠檬酸和正丁醇酯化反应为探针,考察了焙烧温度对其结构与催化活性的影响。实验结果表明,焙烧温度为500℃时,SO4^2-与锆氧化柱形成了具有超强酸性的结构,催化剂活性较佳,能使柠檬酸酯化反应转化率达96．6％,反应酯化率达95．72％。     

固体超强酸SO_4~(2-)/TiO_2负载Tm改性的研究

负载稀土元素 Tm以改性 SO2 - 4 / Ti O2 ,制备出固体超强酸催化剂 Tm- SO2 - 4 / Ti O2 ,并用于催化柠檬酸与正丁醇的酯化反应 .考察了 Tm的负载对催化剂性能的影响 ,并借助吡啶吸附的程序升温脱附 (Py- TPD)法、差热分析 (DTA)、热重分析 (TGA)、红外光谱 (IR)法研究其结构与性能的关系 .实验结果表明 ,Tm的负载 ,使催化剂的催化活性有所提高 ,Tm的加量为催化剂量的 3%时制得的 Tm- SO2 - 4 / Ti O2 ,其催化酯化反应的转化率为94.4% ;Tm的负载能显著降低催化剂表面的积炭量 ,并且有效抑制 SO2 - 4 的流失 ,使 Tm- SO2 - 4 / Ti O2 催化剂具有良好的稳定性 ,重复使用 5次后反应的转化率仍高达 93.1%     

氟离子对TiO2/膨润土光催化降解酸性桃红的影响

研究了在紫外光照射下, 添加氟离子对P25(锐钛矿)和TiO2/膨润土光催化降解酸性桃红(SRB)的影响. 紫外可见光谱测定结果表明无氟的反应体系, pH值越小, 光降解速率越快; pH值固定, 添加氟离子越多, 反应速率越快, 在TiO2/膨润土催化剂上, 当氟离子浓度达到一定程度时, 反应速率不再变化. 在P25和TiO2/膨润土催化剂上, 添加氟离子对H2O2的产生量影响不同, 通过电子顺磁共振(EPR)技术探测到了超氧自由基和羟基自由基, 这两个体系添加氟离子对其产生强度影响不同, 这可能是因为TiO2/膨润土催化剂为层状结构, BET 比表面积较大, 经XRD和TEM测试表明其晶粒直径约为57.9 nm. TiO2/膨润土催化剂连续循环使用11次, 光催化活性基本不变, 这个现象说明TiO2/膨润土催化剂既易于从分散体系中分离出来, 而且其稳定性也好, 它是一个有应用前途的催化剂.     

Molecular structure of Mg-Al, Mn-Al and Zn-Al halotrichites-type double sulfates--an infrared spectroscopic study

Near infrared (NIR), X-ray diffraction (XRD) and infrared (IR) spectroscopy have been applied to halotrichites of the formula MgAl(2)(SO(4))(4)·22H(2)O, MnAl(2)(SO(4))(4)·22H(2)O and ZnAl(2)(SO(4))(4)·22H(2)O. Comparison of the halotrichites in different spectral regions has shown that the incorporation of a divalent transition metal into the halotrichite structure causes a shift in OH stretching band positions to lower wavenumbers. Therefore, an increase of the hydrogen bond strength of the bonded water is observed for divalent cations with a larger molecular mass. XRD has confirmed the formation of halotrichite for all three samples and characteristic peaks of halotrichite have been identified for each halotrichite-type compound. It has been observed that Mg-Al and Mn-Al halotrichite are very similar in structure, while Zn-Al showed several differences particularly in the NIR spectra. This work has shown that compounds with halotrichite structures can be synthesised and characterised by infrared and NIR spectroscopy.     

Coordination of a uraniumIV sulfate monomer in an aqueous solution and in the solid state

UraniumIV sulfate in an aqueous solution and the solid state has been investigated with extended X-ray absorption fine structure (EXAFS) and X-ray diffraction (XRD). The coordination polyhedron comprises monodentate sulfate, bidentate sulfate, and water molecules. The coordination modes of sulfate in solution have been determined from the U-S distances with EXAFS. The U-S distance of 3.67 +/- 0.02 A indicates monodentate sulfate, and the U-S distance of 3.08 +/- 0.02 A indicates bidentate coordination. The obtained sulfur coordination numbers of a solution with a [SO42-]/[U4+] ratio of 40 suggest species with compositions of [U(SO4,bid)2(SO4,mon)2 x nH2O]4- and [U(SO4,bid)3 (SO4,mon)2 x mH2O]6-. Charge-compensating countercations or ion pairing with Na+ and NH4+ could not be detected with EXAFS. One of the solution species, [U(SO4)5H2O]6-, has been conserved in a crystal. The corresponding crystal structure of Na1.5(NH4)4.5[U(SO4)5 x H2O] x H2O [space group P1, a = 9.4995(16) A, b = 9.8903(16) A, c = 12.744(2) A, alpha = 93.669(2) degrees, beta = 103.846(2) degrees, gamma = 109.339(2) degrees] has been determined by single-crystal XRD. Two monomeric uraniumIV sulfate complexes and three sodium units are linked in alternating rows and form a one-dimensional ribbon structure parallel to the a axis.     

Organically directed iron sulfate chains: structural diversity based on hydrogen bonding interactions

Six organically directed 1-D iron sulfates hydrated and hydrolyzed to different extents have been prepared hydrothermally. [C2H10N2]1.5[Fe(SO4)(3)].2H2O (I), [C2H10N2][Fe(SO4)2(OH)].H2O (II), [C6H18N2]0.5[Fe(SO4)2(H2O)2] (III), and [C6H18N2]0.5[Fe2(SO4)(H2O)4(OH)].H2O (V) possess the linear topological structures observed in ferrinatrite, sideronatrite, kr?hnkite, and copiapite minerals, respectively. [C4H12N2][Fe2(SO4)3(OH)2(H2O)2].H2O (IV) shows a novel linear structure that can be regarded as a hybrid of the tancoite and butlerite types. [C6N4H22]0.5[Fe(SO4)2(OH)].2H2O (VI) adopts a cis configuration, compared with II, to give a rare inorganic helical iron sulfate chain which is a new member of the organically directed transitional metal sulfates. The results reveal that the starting molar proportion of the reactants and the type of amines are critical for the structural motif. There is an obvious relationship between the constitution of chains and the type of amino groups, involving the amount of N-H...O hydrogen bonds.     

Microwave investigation of sulfuric acid monohydrate

The complex H2SO4-H2O has been observed by rotational spectroscopy in a supersonic jet. A-type spectra for 18 isotopic forms have been analyzed, and the vibrationally averaged structure of the system has been determined. The complex forms a distorted, six-membered ring with the water unit acting as both a hydrogen bond donor and a hydrogen bond acceptor toward the sulfuric acid. One of the H2SO4 protons forms a short, direct hydrogen bond to the water oxygen, with an H...O distance of 1.645(5) A and an O-H...O angle of 165.2(4) degrees. Additionally, the orientation of the water suggests a weaker, secondary hydrogen bond between one of the H2O hydrogens and a nearby S=O oxygen on the sulfuric acid, with an O...H distance of 2.05(1) A and an O-H...O angle of 130.3(5) degrees. The experimentally determined structure is in excellent agreement with previously published DFT studies. Experiments with HOD in the jet reveal the formation of only isotopomers involving deuterium in the secondary hydrogen bond, providing direct experimental evidence for the secondary H...O interaction. Extensive isotopic substitution has also permitted a re-determination of the structure of the H2SO4 unit within the complex. The hydrogen-bonding OH bond of the sulfuric acid elongates by 0.07(2) A relative to that in free H2SO4, and the S=O bond involved in the secondary interaction stretches by 0.04(1) A. These changes reflect substantial distortion of the H2SO4 moiety in response to only a single water molecule, and prior to the proton transfer event. Spectral data indicate that the complex undergoes at least one, and probably more than one type of internal motion. Although the sulfuric acid in this work was produced from direct reaction of SO3 and water in the jet, experiments with H2(18)O indicate that about 2-3% of the acid is formed via processes not normally associated with the gas-phase hydration of SO3.     

Photosensitive azobispyridine gold(I) and silver(I) complexes

The neutral and cationic dinuclear gold(I) compounds [(μ-N-N)(AuR)(2)] (N-N = 2,2'-azobispyridine (2-abpy), 4,4'-azobispyridine (4-abpy); R = C(6)F(5), C(6)F(4)OC(12)H(25)-p, C(6)F(4)OCH(2)C(6)H(4)OC(12)H(25)-p) and [(μ-N-N){Au(PR(3))}(2)](CF(3)SO(3))(2) (N-N = 2-abpy, 4-abpy, R = Ph, Me) have been obtained by displacement of a weakly coordinated ligand by an azobispyridine ligand. The corresponding silver(I) dinuclear [(μ-2-abpy){Ag(CF(3)SO(3))(PPh(3))}(2)] and polynuclear [{Ag(CF(3)SO(3))(4-abpy)}(n)] compounds have been obtained. The molecular structures of [(μ-2-abpy){Au(PPh(3))}(2)](CF(3)SO(3))(2) and [(μ-4-abpy){Au(PMe(3))}(2)](CF(3)SO(3))(2) have been confirmed by X-ray diffraction studies and feature linear gold(I) centers coordinated by pyridyl groups, and non-coordinated azo groups. In contrast the X-ray structure of [(2-abpy){Ag(CF(3)SO(3))(PPh(3))}(2)] shows tetracoordinated silver(I) centers involving chelating N-N coordination by pyridyl and azo nitrogen atoms. The gold(I) compounds with a long alkoxy chain do not behave as liquid crystals, and decompose before their melting point. The soluble gold(I) derivatives are photosensitive in solution and isomerize to the cis azo isomer under UV irradiation, returning photochemically or thermally to the most stable initial trans isomer. The silver(I) derivative [(2-abpy){Ag(CF(3)SO(3))(PPh(3))}(2)] also photoisomerizes in solution under UV irradiation, showing that its solid state structure, which would block isomerization by azo coordination, is easily broken. These processes have been monitored by UV-vis absorption and (1)H NMR spectroscopy. All these compounds are non-emissive in the solid state, even at 77 K.     

Atom-Resolved EC-STM Studies of Anion Adsorption at Well-Defined Surfaces: Pd(111) in Sulfuric Acid Solution

The interfacial structure of well-defined Pd(111) single-crystal electrodes in 0.05 M H(2)SO(4) has been studied by electrochemical scanning tunneling microscopy (EC-STM) at potentials within the electrical double-layer region. Experiments with (virtually) atomically sharp STM tips yielded images of such quality that the intermolecular and intramolecular structures of the highly ordered compact layer could actually be resolved on an atomic scale. Fundamental concepts in inorganic chemistry have been invoked to postulate that SO(4)(2-), H(3)O(+), and H(2)O are the most likely constituents of the compact layer. A structural model of such a compact layer is presented. Copyright 2000 Academic Press.     

Structural periodicity in plutonium(IV) sulfates

The chemistry of tetravalent Pu with sulfate is explored in a series of single-crystal X-ray diffraction studies of the alkali metal plutonium sulfate compounds. Five new structures of Pu(IV) sulfates are presented including the structure for the α-phase of Pu(SO(4))(2)(H(2)O)(4), Na(10)Pu(2)(SO(4))(9)(H(2)O)(4), K(8)Pu(2)(SO(4))(8)(H(2)O)(5), Rb(8)Pu(2)(SO(4))(8)(H(2)O)(4), and Cs(4)Pu(SO(4))(4)(H(2)O)(2). Changes in structure and stoichiometry are seen down the alkali-metal series despite identical reaction conditions for each of the complexes. Comparison to the other known An(IV) sulfates, Group IV sulfates, and Ce(IV) reveals limited similarity in stoichiometry and structure across the actinide series and their homologues. Marked color changes are observed down the series indicating strong interactions between the plutonium ions and the ligands in these complexes.     

Synthesis, structure, and magnetic properties of amine-templated open-framework nickel(II) sulfates

Two organically templated nickel sulfates of the compositions [C(4)N(2)H(12)][Ni(3)F(2)(SO(4))(3)(H(2)O)(2)] (I) and [C(4)N(2)H(12)][Ni(2)F(4)(SO(4))H(2)O] (II) with open architectures have been synthesized under hydro/solvothermal conditions in the presence of piperazine. I has a layered structure formed by sinusoidal chains comprising hexameric units, whereas II has a three-dimensional structure with 10-membered channels. The layered Ni(II) sulfate, I, is ferrimagnetic, exhibiting hysteresis at low temperatures. The three-dimensional Ni(II) sulfate, II, is essentially paramagnetic. We have also obtained layered compounds isostructural with I containing other amines.     

不同电解质溶液对聚吡咯修饰膜性质的影响

以对甲基苯磺酸钠(p-TSNa)为掺杂剂在不锈钢电极表面恒电位合成聚吡咯(PPy)修饰膜, 采用循环伏安法在-1.6 - 0.8 V大范围扫描研究了修饰膜在H2SO4、Na2SO4、NaOH电解质溶液中的氧化还原行为. 结果表明, 在H2SO4溶液中, 以H+的脱出(氧化)/嵌入(还原)为特征, 并发现聚吡咯在酸性溶液中所特有的质子还原峰. 在Na2SO4和NaOH溶液中, 以Na+的脱出(氧化)/嵌入(还原)峰为特征. FT-IR吸收光谱显示, 经NaOH处理后, 聚吡咯膜的长共轭结构被完全破坏, 而经H2SO4和Na2SO4处后, 膜的共轭结构未发生变化.     

Structural and magnetic properties of iron(II) complexes with 1,4,5,8,9,12-hexaazatriphenylene (HAT)

Reactions of Fe(II) salts with the ligand 1,4,5,8,9,12-hexaazatriphenylene (HAT) led to the isolation and characterization of four new compounds: [Fe3(HAT)(H2O)12](SO4)3.3.3H2O (1), [Fe2(HAT)(SO4)(H2O)5](SO4).2H2O.CH3OH (2), [Fe2(HAT)(SO4)(H2O)5](SO4).3H2O (3), and [Fe3Cl5(HAT)(CH3OH)4(H2O)]Cl (4). Compound 1 crystallizes as a trinuclear cluster in which HAT acts as a tris-chelating ligand. Compounds 2 and 3 are two polymorphs of an infinite one-dimensional structure in which the Fe atoms are coordinated to HAT and then connected into the chain through bridging sulfate anions. Compound 4 exhibits a similar chain structure, but with bridging chloride ligands. The magnetic behavior of the new compounds is indicative of weak antiferromagnetic coupling between the Fe(II) centers through the HAT ligand.