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1.
首次用硬脂法制备了Fe2O3-SiO2混合氧化物,经浸渍H2SO4后再焙烧得SO4^2-/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。  相似文献   

2.
对共沉淀法得到的Fe2O3-SiO2混合氧化物前驱物进行微波水热改性处理,经浸渍(NH4)2S2O8后再焙烧得S2O82-/Fe2O3-SiO2固体酸催化剂。用XRD、TEM、N2气吸附/脱附及化学分析方法对其进行了表征,用乙酸/丁醇酯化催化反应评估固体酸的催化性能,并与通常条件下制得的催化剂进行了比较。结果显示,引入SiO2会延迟Fe2O3晶体的形成与长大;对前驱物用250W的微波水热改性处理1.5h,制得的固体酸具有适中的比表面积、均匀的孔径分布,含硫量为6.02%,比表面积为37.1m2/g。该固体酸对乙酸丁醇酯化反应有很高的催化活性,催化酯化反应3h,乙酸的转化率高达97.7%。  相似文献   

3.
微波水热改性制备S2 /Fe2O3-SiO2固体酸及催化性能   总被引:4,自引:0,他引:4  
吴东辉  金瑞娣  汪信 《应用化学》2005,22(8):879-882
对共沉淀法得到的Fe2O3-SiO2混合氧化物前驱物进行微波水热改性处理,经浸渍(NH4)2S2O8后再焙烧得S2O8^2-/Fe2O3-SiO2固体酸催化剂。用XRD、TEM、N2气吸附/脱附及化学分析方法对其进行了表征,用乙酸/丁醇酯化催化反应评估固体酸的催化性能,并与通常条件下制得的催化剂进行了比较。结果显示,引入SiO2会延迟Fe2O3晶体的形成与长大;对前驱物用250W的微波水热改性处理1.5h,制得的固体酸具有适中的比表面积、均匀的孔径分布,含硫量为6.02%,比表面积为37.1m^2/g。该固体酸对乙酸丁醇酯化反应有很高的催化活性,催化酯化反应3h,乙酸的转化率高达97.7%。  相似文献   

4.
H2SO4-SiO2固体酸的结构及酸性研究   总被引:2,自引:0,他引:2  
以溶胶-凝胶法制备了H2SO4-SiO2固体酸催化剂,并对其结构和酸性进行了系统表征.FT—IR和^29Si—NMR结果表明H2SO4和SiO2间存在相互作用,因此硫酸与硅胶形成稳定的固体、XRD、SEM和TEM结果表明,H2SO4-SiO2固体酸是一多孔无定型材料;BET法测定的H2SO4-SiO2固体酸的比表面积和孔体积结果表明,随着H2SO4与SiO2质量比增加,其比表面减少,孔体积增大;H2SO4-SiO2固体酸的酸强度和液体浓硫酸相当,酸强度与干燥温度和H2SO4加入量有关,固体酸的这一性质以^1H—MAS NMR进行了系统的表征.  相似文献   

5.
Fe2(SO4)3/γ-Al2O3固体超强酸的Mössbauer谱研究   总被引:1,自引:0,他引:1  
采用浸渍法制备了一系列Fe2(SO4)3/ γ-Al2O3型固体超强酸样品,用Moessbauer谱和XRD研究了不同温度处理对样品中铁组分的存在状态及稳定性的影响。结果表明,随Fe2(SO4)3含量的变化,铁组分可以在γ-Al2O3表面以单层分散和无定形形式存在;当温度≥600℃时,无定形状态的Fe2(SO4)3又生成晶态的Fe2(SO4)3,而形成的晶态Fe2(SO4)3即使在700℃时也不分解。  相似文献   

6.
采用浸渍法对无定形ZnO分别用稀H2SO4和(NH4)2S2O8溶液处理, 制备了SO42-/ZnO和S2O82-/ZnO固体酸. 通过固体离子交换法制备了Cu(Ⅰ)/SO42-/ZnO和Cu(Ⅰ)/S2O82-/ZnO两种催化剂, 并采用XRD, FTIR, TPD和TPR等进行了表征. 研究结果表明, 用稀H2SO4和(NH4)2S2O8溶液分别浸渍处理无定形ZnO, 经过500-600 ℃高温焙烧后得到的SO42-/ZnO和S2O82-/ZnO固体酸表面形成了Zn3O(SO4)2物种; py-FTIR结果表明, 两者均具有B酸中心和L酸中心, 进一步的NH3-TPD研究结果证明, 制备的固体酸NH3脱附峰均出现在543 ℃附近, 属于高强度固体酸. 结构分析认为, 由于SO42-强烈的电子诱导作用, SO42-和ZnO形成的桥式配位物种产生了B酸中心和L酸中心, 而其螯合配位形成的物种没有酸性. SO42-/ZnO和S2O82-/ZnO固体酸与CuCl进行离子交换所制备的Cu(Ⅰ)/SO42-/ZnO和Cu(Ⅰ)/S2O82-/ZnO催化剂的Cu(Ⅰ)易于还原, 对甲醇氧化羰基化合成碳酸二甲酯(DMC)表现出较高的活性和选择性, DMC选择性为98.3%, 时空收率可达到1.9 g(g·h).  相似文献   

7.
李丽  张旦萍  范以宁 《无机化学学报》2011,27(11):2201-2204
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。  相似文献   

8.
SO3/Y-Al2O3固体酸催化剂的制备、结构与酸性表征   总被引:3,自引:0,他引:3  
用酸中和法制备了活性γ-Al2O3,并在其表面负载SO3得到固体酸催化剂SO√γ-Al2O3,用XRD,TG-DTA,FT-IR,NMR,NH 3-TPD等对其进行了结构和酸性研究.结果表明在SO√γ-Al2O3的制备过程中形成少量的Al2(SO4)3,同时SO 3与γ-Al2O3表面上的羟基反应,形成强的Bronsted酸位,根据1H/27 Al双共振(TRAPDOR)MAS NMR与FT-IR实验结果提出了Bronsted酸结构模型.SO√γ-Al2O3表面存在两种不同强度的酸中心,其酸强度大于分子筛HZSM-5,但弱于传统的固体超强酸SO2-4/γAl2O3.  相似文献   

9.
S_2O_8~(2-)/ZrO_2-Al_2O_3固体超强酸催化剂的研制与应用   总被引:9,自引:0,他引:9  
固体超强酸因其特殊的晶相结构和表面特性及高比表面积使其具有许多重要的催化特性 [1] ,某些经特殊处理得到的金属氧化物 (如 Zr O2 、Ti O2 、Fe2 O3 等 )负载 SO2 - 4后可以成为固体超强酸[2 ] .有关 SO2 - 4/ Zr O2 系列固体超强酸的研究和应用报道较多[3 ,4 a,5] .夏勇德等[4 b,6 ] 报道用( NH4 ) 2 S2 O8浸渍无定形 Zr( OH) 4可制备超强酸性和催化活性比 SO2 - 4/ Zr O2 更强的新型固体超强酸 S2 O2 - 8/ Zr O2 .本文在文献方法的基础上 ,研制出新型固体超强酸 S2 O2 - 8/ Zr O2 -Al2 O3 ,以乙酸和正丁醇的酯化反应作探…  相似文献   

10.
磁性纳米固体酸催化剂Zr(SO4)2/Fe3O4的制备及催化性能研究   总被引:12,自引:0,他引:12  
本文提出将磁性和固体酸进行组装从而合成磁性纳米固体酸催化剂的思路,首先制备了纳米级磁性前体-磁基体(Fe3O4);然后筛选出超声波法制备了不同配比的磁性纳米固体酸催化剂Zr(SO4)2/Fe3O4,对其进行了初步表征。并将其作为乙酸丁酯合成反应的催化剂,酯化转化率最高达到84%,利用其磁性即可将催化剂进行分离。  相似文献   

11.
The intermolecular potentials for D2, N2, O2, F2 and CO2 are determined on the basis of the second virial coeffincients, the polarizabilities parallel and perpendicular to the molecular axes, and the electric quadrupole moment. The repulsive parts of the potentials are taken from the corresponding Kihara core-potentials. Effects of the octopolar induction are taken into consideration in a unique way. The potential depends on relative orientations of the two molecules as well as the distance r between the molecular centers. This dependence is shown in graphs. A measure of the anisotropy of the potential depth is 0.72 for CO2 0.36 for D2, and smaller than 0.27 for N2 O2 and F2. The remarkable anisotropy for CO2 and D2 is due to strong electrostatic quadrupole interactions.  相似文献   

12.
Phase equilibria in the Ba3(VO4)2-K2Ba(MoO4)2 and Pb3(VO4)2-K2Pb(MoO4)2 systems have been investigated. In the first system, a continuous series of substitutional solid solutions with the palmierite structure is formed, and in the second one, the polymorphic transition in lead orthovanadate at 100°C restricts the extent of the palmierite-type solid solution to 10–100 mol % K2Pb(MoO4)2. Original Russian Text ? V.D. Zhuravlev, Yu.A. Velikodnyi, A.S. Vinogradova-Zhabrova, A.P. Tyutyunnik, V.G. Zubkov, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 10, pp. 1746–1748.  相似文献   

13.
配合物[Cu(H2O)(C12H8N2)2].2ClO4的合成、性质及晶体结构   总被引:1,自引:0,他引:1  
《化学研究与应用》2001,13(5):506-508
合成了配合物[Cu(H2O)(C12H8N2)2]*2ClO4(C12H8N2为1,10-邻菲咯啉),用元素分析、摩尔电导、红外光谱及电子光谱进行了表征,并测定了配合物的晶体结构.该晶体属单斜晶系,空间群为CC;晶胞参数a=1.9177(2)nm,b=0.81994(0)nm,c=1.62458(14)nm,β=100.104(6)°;V=2.5419(4)nm3,Z=4,F(000)=1300,DC=1.693g/cm3,R=0.0430,wR=0.1195.中心铜(Ⅱ)离子与两个1,10-邻菲咯啉的四个N原子和一个水分子的氧原子配位,形成了一个变形的三角双锥结构.  相似文献   

14.
MMe5(dmpe) (M = Nb or Ta, dmpe = Me2PCH2CH2PMe2) reacts with H2 (500 atm) and dmpe in THF at 60°C to give MH5(dmpe)2? NbH5(dmpe)2 readily reacts with two mol of CO or ethylene (L) to give NbHL2(dmpe)2. The exchange of the hydride ligand with the ethylene protons in NbH(C2H4)2(dmpe)2 is not rapid on the 1H NMR time scale (60 MHz) at 95°C.  相似文献   

15.
α-Ca3(BN2)2 crystallizes in the cubic system (space group: ) with one type of calcium ions disordered over of equivalent (8c) positions. An ordered low-temperature phase (β-Ca3(BN2)2) was prepared and found to crystallize in the orthorhombic system (space group: Cmca) with lattice parameters: , , and . Structure refinements on the basis of X-ray powder data have revealed that orthorhombic β-Ca3(BN2)2 corresponds to an ordered super-structure of cubic α-Ca3(BN2)2. The space group Cmca assigned for β-Ca3(BN2)2 is derived from by a group-subgroup relationship.DSC measurements and temperature-dependent in situ X-ray powder diffraction studies showed reversible phase transitions between β- and α-Ca3(BN2)2 with transition temperatures between 215 and 240 °C.The structure Sr3(BN2)2 was reported isotypic with α-Ca3(BN2)2 () with one type of strontium ions being disordered over of equivalent (2c) positions. In addition, a primitive () structure has been reported for Sr3(BN2)2. Phase stability studies on Sr3(BN2)2 revealed a phase transition between a primitive and a body-centred lattice around 820 °C. The experiments showed that both previously published structures are correct and can be assigned as α-Sr3(BN2)2 (, high-temperature phase), and β-Sr3(BN2)2 (, low-temperature phase).A comparison of Ca3(BN2)2 and Sr3(BN2)2 phases reveals that the different types of cation disordering present in both of the cubic α-phases () have a directing influence on the formation of two distinct (orthorhombic and cubic) low-temperature phases.  相似文献   

16.
17.
Single crystals of Cs4[(UO2)2(C2O4)(SO4)2(NCS)2] · 4H2O (I) and (NH4)4[(UO2)2(C2O4)(SO4)2(NCS)2] · 6H2O (II) have been synthesized and studied by X-ray diffraction. The crystals of both compounds are orthorhombic with the space group Pbam, Z = 2, and unit cell parameters a = 12.0177(3) ?, b = 18.6182(5) ?, c = 6.7573(10) ?, R = 0.0376 (I); a = 11.6539(9) ?, b = 18.3791(13) ?, c = 6.7216(5) ?, R = 0.0179 (II). The main structural units of crystals I and II are [(UO2)2(C2O4)(SO4)2(NCS)2]4− chains belonging to the crystal-chemical group A2K02B22M21 (A = UO22+, K02 = C2O42−, B2 = SO42−, M1 = NCS) of the uranyl complexes. The uranium-containing chains are joined into a three-dimensional framework due to a system of electrostatic interactions with the cesium or ammonium ions in the structure of I. In the structure of II, this framework is additionally stabilized by hydrogen bonds involving the outer-sphere water molecules and ammonium ions. Original Russian Text ? I.V. Medrish, A.V. Virovets, E.V. Peresypkina, L.B. Serezhkina, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 7, pp. 1115–1120.  相似文献   

18.
An experimental study on the conversion of NO in the NO/N2, NO/O2/N2, NO/C2H4/N2 and NO/C2H4/O2/N2 systems has been carried out using dielectric barrier discharge (DBD) plasmas at atmospheric pressure. In the NO/N2 system, NO decomposition to N2 and O2 is the dominating reaction; NO conversion to NO2 is less significant. O2 produced from NO decomposition was detected by an on-line mass spectrometer. With the increase of NO initial concentration, the concentration of O2 produced decreases at 298 K, but slightly increases at 523 K. In the NO/O2/N2 system, NO is mainly oxidized to NO2, but NO conversion becomes very low at 523 K and over 1.6% of O2. In the NO/C2H4/N2 system, NO is reduced to N2 with about the same NO conversion as that in the NO/N2 system but without NO2 formation. In the NO/C2H4/O2/N2 system, the oxidation of NO to NO2 is dramatically promoted. At 523 K, with the increase of the energy density, NO conversion increases rapidly first, and then almost stabilizes at 93–91% of NO conversion with 61–55% of NO2 selectivity in the energy density range of 317–550 J L−1. It finally decreases gradually at high energy density. A negligible amount of N2O is formed in the above four systems. Of the four systems studied, NO conversion and NO2 selectivity of the NO/C2H4/O2/N2 system are the highest, and NO/O2/C2H4/N2 system has the lowest electrical energy consumption per NO molecule converted.  相似文献   

19.
Reactions of [Cp2Ti(btmsa)] (btmsa = bis(trimethylsilyl)acetylene) with R4Sb2 (R = Me, Me3Si) give [Cp2TiSbMe2]2 (1) or [Cp2TiSb(SiMe3)2]2 (2) respectively. [Cp2TiCl]2·2Mes4Sb2 (3) is serendipitously formed from [Cp2Ti(btmsa)] and Mes2SbH containing NH4Cl traces.  相似文献   

20.
Three new compounds Ca(HF2)2, Ba4F4(HF2)(PF6)3 and Pb2F2(HF2)(PF6) were obtained in the system metal(II) fluoride and anhydrous HF (aHF) acidified with excessive PF5. The obtained polymeric solids are slightly soluble in aHF and they crystallize out of their aHF solutions. Ca(HF2)2 was prepared by simply dissolving CaF2 in a neutral aHF. It represents the second known compound with homoleptic HF environment of the central atom besides Ba(H3F4)2. The compounds Ba4F4(HF2)(PF6)3 and Pb2F2(HF2)(PF6) represent two additional examples of the formation of a polymeric zigzag ladder or ribbon composed of metal cation and fluoride anion (MF+)n besides PbF(AsF6), the first isolated compound with such zigzag ladder. The obtained new compounds were characterized by X-ray single crystal diffraction method and partly by Raman spectroscopy. Ba4F4(HF2)(PF6)3 crystallizes in a triclinic space group P1¯ with a=4.5870(2) Å, b=8.8327(3) Å, c=11.2489(3) Å, α=67.758(9)°, β=84.722(12), γ=78.283(12)°, V=413.00(3) Å3 at 200 K, Z=1 and R=0.0588. Pb2F2(HF2)(PF6) at 200 K: space group P1¯, a=4.5722(19) Å, b=4.763(2) Å, c=8.818(4) Å, α=86.967(10)°, β=76.774(10)°, γ=83.230(12)°, V=185.55(14) Å3, Z=1 and R=0.0937. Pb2F2(HF2)(PF6) at 293 K: space group P1¯, a=4.586(2) Å, b=4.781(3) Å, c=8.831(5) Å, α=87.106(13)°, β=76.830(13)°, γ=83.531(11)°, V=187.27(18) Å3, Z=1 and R=0.072. Ca(HF2)2 crystallizes in an orthorhombic Fddd space group with a=5.5709(6) Å, b=10.1111(9) Å, c=10.5945(10) Å, V=596.77(10) Å3 at 200 K, Z=8 and R=0.028.  相似文献   

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