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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
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低温陈化超声波共沉淀法制得SO4^2-/ZrO2-La2O3前驱体,经H2SO4处理,在不同温度下焙烧得到纳米晶催化剂SO4^2-/ZrO2-La2O3;用Hammett指示剂法测定其酸性.用XRD、BET、TEM、IR和XPS对样品进行表征,其催化活性用醋酸和甘油的酯化反应进行了评价.结果表明经超声波搅拌和低温(-15℃)陈化,650℃焙烧4h得到的固体超强酸表现出较高催化活性. 相似文献
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固体超强酸SO2-4/SnO2-Al2O3的红外光谱研究 总被引:2,自引:0,他引:2
以四氯化锡、硫酸铝为原料,氨水为沉淀剂,采用共沉淀法制得新型固体超强酸SO2-4/SnO2-Al2O3.采用FT-IR技术考察了金属元素摩尔比、焙烧温度、浸渍液以及掺杂稀土氧化物对该固体超强酸结构和性能的影响.FT-IR结果表明在该固体超强酸中,锡和硫酸根是以螯合和桥式两种方式配位结合,其中起催化活化作用的主要是和硫酸根以螯合双齿结合的锡;和SO2-4/ZrO2型超强酸相比,SO2-4/SnO2-Al2O3超强酸的硫酸根FT-IR特征吸收峰发生蓝移,显示出更强的酸性.锡铝摩尔比为9∶1、焙烧温度为773K、焙烧时间为3h时,制得的SO2-4/SnO2-Al2O3样品对酯化反应的催化性能最好. 相似文献
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以四氯化锡、硫酸铝为原料,氨水为沉淀剂,采用共沉淀法制得新型固体超强酸SO42-/SnO2-A l2O3。采用FT-IR技术考察了金属元素摩尔比、焙烧温度、浸渍液以及掺杂稀土氧化物对该固体超强酸结构和性能的影响。FT-IR结果表明在该固体超强酸中,锡和硫酸根是以螯合和桥式两种方式配位结合,其中起催化活化作用的主要是和硫酸根以螯合双齿结合的锡;和SO42-/ZrO2型超强酸相比,SO42-/SnO2-A l2O3超强酸的硫酸根FT-IR特征吸收峰发生蓝移,显示出更强的酸性。锡铝摩尔比为9∶1、焙烧温度为773K、焙烧时间为3h时,制得的SO42-/SnO2-A l2O3样品对酯化反应的催化性能最好。 相似文献
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SO2-4/ZrO2/Fe3O4/Al2O3磁性固体超强酸的制备与表征 总被引:5,自引:0,他引:5
用化学共沉淀法制备了一系列SO2-4/ZrO2/Fe3O4/Al2O3磁性固体超强酸, 利用XRD、IR、TG-DSC、VSM、TEM及HRTEM等手段对样品结构进行了表征. 结果表明, 引入一定量的Fe3O4和Al2O3有利于四方晶相ZrO2(t)结构的稳定;Fe3O4超细粒子的引入, 使固体超强酸具备了超顺磁性;HRTEM 结果显示ZrO2晶体生长趋向于ZrO2(t)的[101]方向,其(101)晶面间距为d(101)=0.29 nm, 与XRD 衍射结果一致. Hammett 指示剂测得样品SZA-20-200-800酸强度(H0<-13.8)最强, 酸性大于浓硫酸(H0=-11.9). 相似文献
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M. Grehl R. Frhlich S. Thiele 《Acta Crystallographica. Section C, Structural Chemistry》1995,51(6):1038-1040
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Haloacetyl, peroxynitrates are intermediates in the atmospheric degradation of a number of haloethanes. In this work, thermal decomposition rate constants of CF3C(O)O2NO2, CClF2C(O)O2NO2, CCl2FC(O)O2NO2, and CCl3C(O)O2NO2 have been determined in a temperature controlled 420 l reaction chamber. Peroxynitrates (RO2NO2) were prepared in situ by photolysis of RH/Cl2/O2/NO2/N2 mixtures (R = CF3CO, CClF2CO, CCl2FCO, and CCl3CO). Thermal decomposition was initiated by addition of NO, and relative RO2NO2 concentrations were measured as a function of time by long-path IR absorption using an FTIR spectrometer. First-order decomposition rate constants were determined at atmospheric pressure (M = N2) as a function of temperature and, in the case of CF3C(O)O2NO2 and CCl3C(O)O2NO2, also as a function of total pressure. Extrapolation of the measured rate constants to the temperatures and pressures of the upper troposphere yields thermal lifetimes of several thousands of years for all of these peroxynitrates. Thus, the chloro(fluoro)acetyl peroxynitrates may play a role as temporary reservoirs of Cl, their lifetimes in the upper troposphere being limited by their (unknown) photolysis rates. Results on the thermal decomposition of CClF2CH2O2NO2 and CCl2FCH2O2NO2 are also reported, showing that the atmospheric lifetimes of these peroxynitrates are very short in the lower troposphere and increase to a maximum of several days close to the tropopause. The ratio of the rate constants for the reactions of CF3C(O)O2 radicals with NO2 and NO was determined to be 0.64 ± 0.13 (2σ) at 315 K and a total pressure of 1000 mbar (M = N2). © 1994 John Wiley & Sons, Inc. 相似文献
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Henry G. Giesber Michael B. Korzenski William T. Pennington Joseph W. Kolis 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):399-400
The compound diiron diphosphate dihydrate, Fe2P2O7(H2O)2, was synthesized hydrothermally and crystallizes in the monoclinic space group P21/n. The compound has a somewhat open framework made up of edge‐sharing iron(II) octahedra that form chains connected by five bridging diphosphates. The remaining octahedral site of each iron is occupied by coordinated water. The H atoms of the water molecules all point into a common channel. 相似文献
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《The Journal of chemical thermodynamics》2007,39(11):1474-1492
High-temperature heat capacity measurements were obtained for Cr2O3, FeCr2O4, ZnCr2O4, and CoCr2O4 using a differential scanning calorimeter. These data were combined with previously available, overlapping heat capacity data at temperatures up to 400 K and fitted to 5-parameter Maier–Kelley Cp(T) equations. Expressions for molar entropy were then derived by suitable integration of the Maier–Kelley equations in combination with recent S∘(298) evaluations. Finally, a database of high-temperature equilibrium measurements on the formation of these oxides was constructed and critically evaluated. Gibbs free energies of Cr2O3, FeCr2O4, and CoCr2O4 were referenced by averaging the most reliable results at reference temperatures of (1100, 1400, and 1373) K, respectively, while Gibbs free energies for ZnCr2O4 were referenced to the results of Jacob [K.T. Jacob, Thermochim. Acta 15 (1976) 79–87] at T = 1100 K. Thermodynamic extrapolations from the high-temperature reference points to T = 298.15 K by application of the heat capacity correlations gave ΔfG∘(298) = (−1049.96, −1339.40, −1428.35, and −1326.75) kJ · mol−1 for Cr2O3, FeCr2O4, ZnCr2O4, and CoCr2O4, respectively. 相似文献
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Neven Strukan Marina Cindri Boris Kamenar 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):639-641
The crystal and molecular structure of dipotassium di‐μ‐oxo‐bis[aqua(oxalato‐O1,O2)oxomolybdenum(III)] trihydrate, K2[Mo2O4(C2O4)2(H2O)2]·3H2O, has been determined from X‐ray diffraction data. In the dimeric anion, which has approximate twofold symmetry, each Mo atom is in a distorted octahedral coordination, being bonded to one terminal oxo‐O atom, two bridging O atoms, two O atoms from the oxalato ligand and one from the water molecule. Bond lengths trans to the multiple‐bonded terminal oxo ligand are larger than those in the cis position, confirming the trans influence as a generally valid rule. 相似文献
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Heinz Follner 《无机化学与普通化学杂志》1970,373(2):198-203
LiHC2O4 · H2O crystallizes in space group P 1 with a0 = 4.99, b0 = 6.16, c0 = 3.45 Å; α0 = 96.3°, β0 = 98.0°, γ0 = 80.4° and Z = 1. The crystal structure has been determined by direct methods. Refinement by least squares methods resulted to R1 = 8,3%. In the structure the oxalate group is not planar. The angle between the two O? C? O planes is 2.9°. 相似文献
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U. Wannagat K. -P. Giesen H. -H. Falius 《Monatshefte für Chemie / Chemical Monthly》1973,104(5):1444-1452
Compounds I-X of the sixmembered ring system PSi2N2O with phosphorus in different oxidation and bond numbers, collected in Schema 1, have been prepared for the first time and confirmed in their structure by elemental analysis as well as by infrared and1H- and31P-spectroscopy.
Mit Auszügen aus der DissertationK. P. Giesen, Techn. Univ. Braunschweig 1972. 相似文献
Mit Auszügen aus der DissertationK. P. Giesen, Techn. Univ. Braunschweig 1972. 相似文献
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Marcella Cadoni Giovanni Ferraris 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(11):i87-i90
The crystal structure of synthetic penkvilksite‐2O, disodium titanium tetrasilicate dihydrate, Na2TiSi4O11·2H2O, a microporous titanosilicate, confirms the major features of a previous model that had been obtained by order–disorder (OD) theory from the known structure of penkvilksite‐1M. An important difference from the previous model involves the hydrogen bonding of the water molecule which, on the basis of a Raman spectrum and the finding of only one of the two H atoms, is proposed to be disordered about a fixed O–H direction. The structure of penkvilksite‐2O is based on (100) silicate layers linked by isolated TiO6 octahedra to form a heteropolyhedral framework. The layer is strongly corrugated, based on interlaced spiral chains, and is crossed by two different channels that have an effective channel width of about 3 Å. 相似文献