磁性超细固体酸催化剂SO4^2——ZrO2／Fe3O4的组装及表征

将磁性Fe3O4纳米材料和SO4^2--ZrO2固体酸进行组装，制得一系列具有磁性和超细粒子结构的固体酸催化剂SO4^2--ZrO2/Fe3O4，采用XRD，TG－DTA和XPS等分析测试手段对催化剂的结构和性能进行了表征。并分析和测试了催化剂的磁学性能、比表面积、粒度分布和元素的组成等物理化学性质。该催化剂具有较小的粒度、较高的磁性及酯化催化活性，对乙酸丁酯合成反应的催化活性可达66％；利用Fe3O4的磁性可对催化剂进行分离和回收。经高温处理后，固体超强酸的形成对催化剂磁性、比表面积、表相原子的电子结合能以及各组分形态均有显著影响。     

磁性纳米固体酸SO42--TiO2-Fe3O4催化剂的合成、表征及催化性能的研究

首先研究制备了Fe3O4和SO42--TiO2固体酸催化剂,在此基础上采用共沉淀和浸渍的方法制备了磁性和超细SO42--TiO2-Fe3O4固体酸催化剂。利用XRD,TEM和FT-IR等分析测试手段对催化剂的结构和性能进行了表征。测定结果证实该催化剂具有较小的粒度,较高的磁性表现。在乙酸丁酯合成反应中SO42--TiO2-Fe3O4展示了很高的催化活性(酯化率可达82.7%),而且利用Fe3O4的磁性可对催化剂进行分离和回收.     

磁性纳米固体酸SO4^2ˉ-TiO2-Fe3O4催化剂的合成、表征及催化性能的研究

首先研究制备了Fe3O4和SO4^2ˉ-TiO2固体酸催化剂，在此基础上采用共沉淀和浸渍的方法制备了磁性和超细SO4^2ˉ-TiO2-Fe3O4固体酸催化剂。利用XRD，TEM和FT—IR等分析测试手段对催化剂的结构和性能进行了表征。测定结果证实该催化剂具有较小的粒度，较高的磁性表现。在乙酸丁酯合成反应中SO4^2ˉ-TiO2-Fe3O4展示了很高的催化活性（酯化率可达82．7％），而且利用Fe3O4的磁性可对催化剂进行分离和回收．     

新型磁性纳米固体酸催化剂ZrO2/Fe3O4的制备及表征

根据将磁性一材料和固体酸进行组装的设想，成功制备了磁性纳米固体酸催化剂。纳米级样性前体-磁基体(Fe3O4)的磁性、粒子尺寸受到Fe^2^+/Fe^3^+投料比和用于沉淀的NaOH浓度的显著影响；不同复合方法也对磁性固体酸催化剂ZrO2/Fe3O4的酯化催化性能影响显著。XRD，XPS，TEM，比表面积测定，元素组成分析及磁学性能测定等表征结果证实，新型催化剂以磁性材料为核，固体酸催化剂活性组分包覆在其外部形成包覆型的磁性纳米催化剂。该系列催化剂均具有较小的粒子尺寸、较强的磁性及较高的酯化催化活性；并且易于通过磁场进行回收，使用寿命较长。它们对乙酸与正丁醇酯化反应的催化活性随着ZrO2含量增加而提高。催化剂中ZrO2的晶化温度因为Fe3O4的存在而升高，有利于催化剂活性的保持，热处理温度会对催化剂的磁性及催化活性产生影响。     

硬脂酸法制备SO42-/Fe2O3-SiO2固体酸及其催化性能的初步探讨

首次用硬脂酸法制备了Fe2O3-SiO2混合氧化物,经浸渍H2SO4后再焙烧得SO2-4/Fe2O3-SiO2固体酸催化剂.用TEM,XRD,N2吸附/脱附和TG-DTA等手段对其进行了表征,结果显示制得的Fe2O3-SiO2混合氧化物具有多孔结构.且随着Si含量的增大,其比表面积明显增大,但孔径减小.用乙酸/丁醇酯化催化反应评估了该固体酸的催化性能.     

磁性固体超强酸SO2-4/TiO2-Fe3O4的制备及表征

固体超强酸是近年来研制开发出的一类新型催化材料[1-4],其克服了传统液体酸催化剂易腐蚀设备、污染环境、副反应多、产物选择性低等缺点.尤其是近年来纳米技术的应用,使得纳米级固体超强酸的研究颇受人们的青睐.但纳米级固体超强酸催化剂在与液体产物的分离及回收中存在困难.为了进一步改良纳米固体超强酸的性能,本研究将磁基体Fe3O4与固体超强酸复合,制得磁性纳米固体超强酸SO42-/ TiO2 - Fe3O4,并对其结构和催化性能进行了表征.     

磁性纳米复合氧化物固体酸催化剂的制备及酯化性能

固体酸催化剂的无腐蚀、环境友好和可循环使用等特点使其成为无机液体酸的最佳替代物.磁性纳米固体酸具有优于常规固体酸催化剂的催化活性及分离简单的特性.用共沉淀法分别合成了一系列三组分TiO2-Al2O3-Fe3O4(TAF)和CeO2-Al2O3-Fe3O4(CAF)及四组分ZrO2--Al2O3-Fe3O4(ZACF)磁性纳米复合氧化物固体酸催化剂,通过电感耦合等离子体原子发射光谱、比表面积测定、X射线衍射、透射电镜、热重分析和红外光谱等对其进行了表征,并利用酯化反应作为探针反应评价了其催化性能.结果表明,合成的磁性纳米固体酸催化剂在酯化反应中表现出很好的催化活性.     

SO42-/TiO2-ZrO2复合氧化物固体酸催化剂的长叶烯芳构化催化性能

本工作用溶胶-凝胶法制备不同组成的SO42-/TiO2-ZrO2复合氧化物固体酸催化剂,用微型催化反应评价结合X-射线粉末衍射(XRD)、孔结构/BET表面积测试和NH3-程序升温脱附(NH3-TPD)等表征了SO42-/TiO2-ZrO2复合氧化物固体酸催化剂结构、表面酸性和长叶烯芳构化催化性能。复合氧化物固体酸SO42-/TiO2-ZrO2催化剂具有优良的长叶烯芳构化催化性能,并且其芳构化催化性能与催化剂组成和表面酸性密切相关。随催化剂中nZr/(nZr+nTi)增加,催化剂表面中等强度的酸中心量增加,芳构化产物选择性和收率明显增加,在nZr/(nZr+nTi)=0.5时达极大值。随nZr/(nZr+nTi)进一步增加,不仅催化剂表面酸中心量减少、原料转化率明显下降,而且催化剂酸强度增强,导致芳构化产物选择性和收率下降。催化长叶烯芳构化的二元复合氧化物固体酸SO42-/TiO2-ZrO2催化剂适宜的组成为nZr/(nZr+nTi)=0.5。     

焙烧温度对纳米级SO2- 4/TiO2固体超强酸性能的影响

用锐钛型纳米TiO2制备了纳米级SO2- 4/TiO2固体超强酸,考查了焙烧温度对酸强度、比表面积、红外光谱及其催化活性的影响.结果显示该催化剂在450℃焙烧3 h,可以形成纳米级SO2-4/TiO2固体超强酸的结构.用该催化剂催化乙酸和丁醇酯化反应可使酯化率达到98.4%.     

超声吸附制备均匀分散在SBA-15的S2O82--Fe2O3纳米粒子:增强S2O82--Fe2O3本体催化活性

酸催化剂在化学反应和化工生产中具有重要的作用.传统无机酸,如H2SO4,H3PO4和对甲苯磺酸等具有较高的催化活性,但是存在污染大、设备腐蚀严重以及催化剂不能重复使用等问题.固体酸具有酸性强、易分离、环境友好以及稳定性和重复使用性好等特点因而近年来越来越引起人们的关注.其中,SO42--MxOy固体超强酸(如SO42--ZrO2,SO42--TiO2和SO42--SnO2等)因具有很好的催化性能而备受关注.相比SO42--MxOy,S2O82--MxOy具有更强的酸性和稳定性而成为研究的重点.如何克服固体超强酸本体的低比表面积和孔容,增加其比表面积和催化活性是固体超强酸研究的热点.超声吸附法可保证所制介孔固体酸活性组分均匀分散,以及大的比表面积和更多的酸性位点.因此采用超声吸附法制备了一种新型介孔固体酸S2O82--Fe2O3/SBA-15.相比S2O82--Fe2O3本体、B酸和文献报道催化剂,负载30%Fe2O3的S2O82--Fe2O3/SBA-15在环氧苯乙烷甲醇醇解的探针反应中显示出很高的催化活性,反应收率为100%.S2O82--Fe2O3纳米粒子的纳米效应和SBA-15介孔结构的协同作用使S2O82--Fe2O3/SBA-15具有高催化活性.相比S2O82--Fe2O3本体,采用超声分散技术制备的S2O82--Fe2O3/SBA-15固体超强酸具有典型的介孔结构、大的比表面和孔容,并且表面富含酸性位点.并且吡啶红外分析S2O82--Fe2O3/SBA-15表面富含L酸和B酸.环氧苯乙烷甲醇醇解探针反应表明,Fe2O3负载量为30%时,S2O82--Fe2O3/SBA-15的催化活性最高,优于S2O82--Fe2O3本体和已报道的布朗酸和路易斯酸等催化剂,将醇底物拓展(ROHs,R = C2H5-C4H9),S2O82--Fe2O3/SBA-15的催化活性也优于S2O82--Fe2O3本体.同时,S2O82--Fe2O3/SBA-15具有很好的重复使用性能,连续使用七次,反应收率在84.1%以上.总之,具有高催化活性、好的稳定性和经济性的S2O82--Fe2O3/SBA-15具有广阔的应用前景.     

Ternary systems LiBr-Li2MoO4-Li2WO4 and LiF-Li2MoO4-Li2WO4

The ternary systems LiBr-Li₂MoO₄-Li₂WO₄ and LiF-Li₂MoO₄-Li₂WO₄ were studied by differential thermal analysis. The fields of crystallizing phases are delimited, and di- and monovariant equilibria for surfaces and monovariant curves are described.     

Kristallstrukturen von MgCr2O4-Typ Li2VCl4 und Spinell-Typ Li2MgCl4 und Li2CdCl4

Crystal Structures of MgCrO₄-type Li₂VCl₄ and Spinel-type Li₂MgCl₄ and Li₂CdCl₄ The crystal structures of the ternary lithium chlorides Li₂MCl₄ (M = Mg, V, Cd) have been determined firstly by X-ray single-crystal experiments. Li₂MgCl₄ and Li₂CdCl₄ crystallize in an inverse spinel structure (space group Fd3 m, Z = 8, a = 1 040.1(2) and 1 062.06(9) pm, structural parameters u = 0.25699(2) and 0.2550(1), R = 1.7 and 3.7% for 218 and 211 unique reflections). The Li? Cl distances of the tetrahedrally coordinated Li⁺ ions are significantly greater than calculated with Shannon's crystal radii ( > 238 ± 1 instead of 233 pm). Contrary to the results of X-ray powder data reported in the literature, Li₂VCl₄ crystallizes in the distorted spinel structure of MgCr₂O₄ type (space group F4 3m, Z = 8, a = 1 037.49(2) pm, R = 5.9% for 217 unique reflections). The decrease of the site symmetry of the octahedrally coordinated ions (V²⁺, Li⁺) from 3 m to 3m resulting in contracted and widened tetrahedral M₄ entities of the spinel structure is obviously caused by V? V metal—metal bonds (shortest V? V distance 366.2(7) pm).     

Zur Kenntnis der Chlorid-Spinelle Li2MgCl4, Li2MnCl4, Li2FeCl4, Li2CdCl4

About the Chloride Spinels Li₂MgCl₄, Li₂MnCl₄, Li₂FeCl₄, Li₂CdCl₄ FIR, Raman, and X-ray data of the spinel type chlorides Li₂TCl₄ (T = Mg, Mn, Fe, Cd) are presented. The vibrational spectra indicate that there is no 1:1 ordering on the octahedral sites of the lattice. Both DTA measurements and high temperature X-ray photographs show that the chloride spinels undergo a reversible phase transition to a cubic high temperature defect structure at 535°C (Li₂MgCl₄), 460°C (Li₂MnCl₄) and 385°C (Li₂CdCl₄), which has unit cell dimensions two times smaller than the spinel lattice. Disordering of the lithium sublattice still begins at much lower temperatures, as measurements of the electric conductivity indicate.     

Darstellung und Struktur von BaAl2Se4, BaGa2Se4, CaGa2Se4 und Caln2Te4

Preparation and Crystal Structure of BaAl₂Se₄, BaGa₂Se₄, CaGa₂Se₄, and CaIn₂Te₄ The new compounds BaAl₂Se₄, BaGa₂Se₄, CaGa₂Se₄ and CaIn₃Te₄ crystallize with constants see “Inhaltsübersicht”. The structures are strongly related to the TlSe structure.     

Studies on Li2SO4-MgSO4 and Li2SO4-Li4SiO4 systems

The phase equilibria as well as the properties and crystal structures of the compounds formed in both Li₂SO₄-MgSO₄ and Li₂SO₄-Li₄SiO₄ systems have been studied by means of x-ray diffraction technique (at high and room temperatures) as well as by the thermal analyses (DTA, DSC, TGA, etc.). In Li₂SO₄-MgSO₄ system there exists a compound Mg₄Li₂(SO₄)₅ formed by peritectic reaction at 840°C and decomposed at 105°C into the Li₂SO₄-base solid solution and MgSO₄ · Mg₄Li₂(SO₄)₅ and Li₂SO₄-base solid solution conduct an eutectic reaction at 663°C with the composition of eutectic point lying in 22 mol% MgSO₄. The solubility of MgSO₄ in Li₂SO₄ is a little smaller than 10 mol% while at the same time the Li₂SO₄ phase transition temperature decreases from 574 to 560°C On the other hand, no noticeable solid solubility of Li₂SO₄ in MgSO₄ has been observed. The reaction is an endothermal one and its heat of formation is 2.57 kJ/mol. The activation energy of the reaction calculated by thermal peak displacement method at various heating rates is 173.5 kJ/mol (1.80 ev). The crystal Mg₄Li₂(SO₄)₅ belongs to orthorhombic system with lattice parameters at 180°C: a = 8.577, b=8.741, c= 11.918 Å. The space group seems to be either P222 or P mmm. Assuming that there are two formula units in a unit cell, the density calculated is then 2.20 g/cm³ very close to that of Li₂SO₄ or MgSO₄. Meanwhile, in Li₂SO₄-Li₄SiO₄ system a new phase Li_8-2x(SiO₄)_8-x(SO₄)_x is formed by peritectic reaction at 953°C with a range of composition x=0.96 ?0.58. The crystal belongs to ortho-rhombic system with lattice parameters at x=0.8: a = 5.002, b= 6.173 and c=10.608Å. The density observed is 2.31 g/cm³ and there are 2 formula units in an unit cell. It is shown from the measurements of piezoelectric and laser SHG coefficients of the crystal that the crystal posseses a symmetrical center with the space group belonging to P mmn. The lattice parameter c has a maximum at x=0.8. In the air Li_8-2x(SiO₄)_2-x(SO₄)_x can absorb 7.6 wt% water vapour and other gases which can only be desorbed by heating it at a temperature above 350°C. Neither absorption nor desorbtion can change its crystal structure, a characteristic similar to that of zeolite molecular sieve. The dewater activation energy of Li_8-2x(SiO₄)_2-x(SO₄)_x is 171.5 kJ/mol. Li_8-2x(SiO₄)_2-x(SO₄)_x and Li₄SO₄ bring about an eutectic reaction at 823°C with its eutectic composition being 12 mol% Li₄SiO₄. No observable solubility of Li₄SiO₄ in Li₃SO₄ has been noticed. The solubility of Li₂SO₄ in Li₄SiO₄ is approximately equal to 5 mol%. With Li₂SO₄ being dissolved in, the phase transition temperature of Li₄SiO₄ is decreased. After being fused, the specimens Li₃SO₄-MgSO₄ and Li₂SO₄-Li₄SiO₄ are cooled at a rate of 10°C/min, their metastable eutectic systems are resulted respectively.     

Li~2SO~4-MgSO~4、LiSO~4-Li~4SiO~4体系的研究

本文用X射线衍射(高温、室温)和热分析(DTA、DSC、TGA)等方法测定了Li~2SO~4-MgSO~4和Li~2SO~4-Li~4SO~4体系相图,并研究了化合物的性能和晶体结构。Mg~4Li~2(SO~4)~5在840℃由包晶反应形成,它在105℃分解为Li~2SO~4为基的固溶体和MgSO~4.在105℃反应时,形成每摩尔的Mg~4Li~2(SO~4)~5吸热2.57kJ,反应激活能为173.5kJ/mol. Mg~4Li~2(SO~4)~5属正交晶系,在180℃的点阵常数α=8.577A,b=8.741A, c=11.918A, 可能的空间群为P222或Pmmm,Z=2。Li~8-2x(SiO~4)~2-x(SO~4)~x是在953℃由包晶反应形成的新相.随着温度的降低,相区扩大,在室湿x=0.96-0.58.该相属正交晶系,空间群为Pmmn,Z=2.晶体的点阵常数在x=0.8时有一定最大值,a=5.002A,b=6.173A, c=10.608A.Li~g-2x(SiO~4)~2-x(SO~4)~x在空气中能吸收7.6wt%的水蒸汽和其他气体,脱水温度高于350℃,水份的吸脱不改变晶体结构,与沸石分子筛具有相似性质,脱水激活能为171.5kJ/mol.熔化后的Li~2SO~4-MgSO~4和Li~2SO~4-Li~4SiO~4试样以10℃/min速率降温,分别形成亚稳态共晶体系。     

Synthesis and Characterization of Gd2[Pt2(SO4)4(HSO4)2](HSO4)2

Red single crystals of Gd₂[Pt₂(SO₄)₄(HSO₄)₂](HSO₄)₂ (triclinic, , Z = 1, a = 844.02(9), b = 908.50(9), c = 939.49(8) pm, α = 107.73(1)°, β = 112.10(1)°, γ = 103.53(1)°) were obtained by the reaction of [Gd(NO₃)(H₂O)₇][PtCl₆]·4H₂O with sulfuric acid at 320 °C in a sealed glass ampoule. In the crystal structure, Pt₂ dumbbells are coordinated by four chelating sulfate groups and two monodentate hydrogensulfate ions. Two further HSO₄^? ions are not bonded to the Pt₂ dumbbell. The Gd³⁺ ions are eightfold coordinated by oxygen atoms. The IR data of Gd₂[Pt₂(SO₄)₄(HSO₄)₂](HSO₄)₂ are typical for these type of compounds. The thermal decomposition of the compound leads to elemental platinum and Gd₂O₃.     

Four-component system LiF-K2WO4-CaF2-CaWO4

The four-component system LiF-K₂WO₄-CaF₂-CaWO₄ has been studied by physicochemical analysis. The phase and crystallization trees have been predicted a priori and have been experimentally verified by constructing a topological model of the phase diagram and by solving the equations expressing the general law of liquidus surface formation. The heat-storage properties of the eutectic compositions are evaluated.     

Na2Co(H2PO4)4·4H2O

In the title compound, disodium cobalt tetrakis­(dihydrogen­phosphate) tetrahydrate, the Co^II ion lies on an inversion centre and is octahedrally surrounded by two water molecules and four H₂PO₄ groups to give a cobalt complex anion of the form [Co(H₂PO₄)₄(OH₂)]^2?. The three‐dimensional framework results from hydrogen bonding between the anions. The relationship with the structures of Co(H₂PO₄)₂·2H₂O and K₂CoP₄O₁₂·5H₂O is discussed.