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铂铼、铂锡、铂铱等双金属催化剂已有报道,但有关以稀土金属为第2或第3组分的重整催化剂的报道尚很少见,本文报道用中毒法对PtY/Al_2O_3的金属活性中心性质的研究,试图探讨其活性中心与催化性质的某些联系。 1 实验部分 按文献[1]制备催化剂,其中Pt、Y、Cl含量分别为0.3、0.1、1.0 wt%,使用前不焙烧,比 相似文献
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B2O3/ZrO2催化剂稳定性和再生性能的研究 总被引:3,自引:1,他引:3
以气相环己酮肟重排反应合成己内酰胺是多相催化研究领域的重要课题之一[1,2]. 本研究小组曾首次报道了B2O3/ZrO2催化剂对该反应表现出较高的活性和己内酰胺选择性,但是该催化剂的稳定性和再生性能较差[3,4]. 而通过对催化剂的组成和结构与己内酰胺产率关系的研究表明,当B2O3在ZrO2载体(60 m2/g)表面平均形成约两个单层厚度的B2O3表面相时催化剂性能最好[2],这预示着增加ZrO2载体的比表面积可望改善B2O3/ZrO2催化剂的性能. 采用常规方法制备的ZrO(OH)2经600 ℃焙烧后所得ZrO2的比表面积一般不超过60 m2/g. 本文以蒸煮回流ZrO(OH)2水凝胶的方法制备了高比表面积的ZrO2,并考察了以其为载体的B2O3/ZrO2催化剂对气相环己酮肟重排反应的催化性能. 相似文献
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吡啶类含氧化合物是一类很重要的有机化合物 ,在药物、食品和饲料添加剂、染料工业等诸多领域应用极为广泛。关于吡啶羧酸的制备 ,实验室和工业上都有较多的研究报道[1 ] 。但不外乎两大类 ,一类反应是化学计量氧化法 ,如高锰酸钾氧化法[1 ] 和硝酸氧化法[2 ,3] ,这类方法原料消耗量大 ,成本高 ,不适合于规模生产。另一类反应是催化氧化法 ,对这类反应研究的报道 ,工业上普遍采用的一种生产工艺是氨氧化法[1 ] ,此法是工业上生产烟酰胺和烟酸的重要方法之一 ,其条件苛刻。文献[4~ 6] 报道以醋酸作溶剂、以醋酸钴、醋酸锰和溴化物作催化剂 ,… 相似文献
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异构烷烃与烯烃的烷基化是炼油装置制备高辛烷值汽油添加剂的重要途径.目前传统工艺仍使用矿物酸如硫酸或氢氟酸作催化剂,由于该工艺存在着产物分离困难、设备腐蚀严重及环境污染问题,从60年代起国内外开始致力于新型固体酸催化剂的研究与开发工作,已报道的有离子交换树脂[1]、分子筛催化剂[2]及SO=4/MxOy型催化剂[3]等,在分子筛催化剂中已报道的有立方沸石[4]β-分子筛[5]、ZSM系列[5]、分子筛[5]、蒙脱石[5]及MCM-22[6]等,这些催化剂的共性是催化活性较高,但失活较快.目前对分子筛催化剂的研究主要集中在改进的立方沸石体系,而六方沸石催化剂催化异丁烷与丁烯烷基化反应尚未见报道. 相似文献
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新型超分子化合物C6H20N2O64P2MO18·8H2O 的晶体结构及电催化作用 总被引:20,自引:0,他引:20
多酸是较好的受体分子,当它与有机电子给体作用时,可形成超分子化合物.90年代初这类化合物的研究才刚刚起步.作为一类新型电、磁、非线性光学材料极具开发价值[1].用氨基酸作为电子给体对生物活性研究意义重大[2],有关Keggin结构的超分子化合物已见报道[3],但标题化合物这类手性阴离子[4]与手性氨基酸所形成的杂多化合物及单晶结构尚未见文献报道. 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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Rychlowska-Himmel I. Blonska-Tabero A. 《Journal of Thermal Analysis and Calorimetry》1999,56(1):205-210
Studies on the reactivity of ZnFe2O4 towards ZnV2O6 revealed that in the solid state the phases interact in a molar ratio of 1:3 to form a new compound, to which the molecular
formula Zn2FeV3O11 was assigned. The compound melts congruently at 825±5°C.
This revised version was published online in July 2006 with corrections to the Cover Date. 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