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1.
Hans R. Kricheldorf Lali Vakhtangishvili Gert Schwarz 《Journal of polymer science. Part A, Polymer chemistry》2004,42(22):5725-5735
Poly(pyridine ether)s were prepared in two ways: the polycondensation of silylated 1,1,1‐tris(4‐hydroxyphenyl)ethane (THPE) with 2,6‐difluoropyridine (method A) and the polycondensation of free THPE with 2,6‐dichloropyridine (method B). With method A, the THPE/difluoropyridine feed ratio was varied from 1.0:1.0 to 1.0:1.6. Cycles, bicycles, and multicycles were the main reaction products, and crosslinking was never observed. When ideal stoichiometry was used exclusively, multicycles free of functional groups were obtained. These multicycles were detectable in matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectra up to B38C76 with a mass of approximately 32,000 Da. With method B, the reaction conditions were varied at a fixed feed ratio to achieve an optimum for the preparation of multicyclic polyethers, but because of the lower reactivity of 2,6‐dichloropyridine, a quantitative conversion was not achieved. The reaction products were characterized with MALDI‐TOF mass spectrometry, viscosity measurements, and size exclusion chromatography. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5725–5735, 2004 相似文献
2.
Styrene (STY) is now produced industrially in fairly large quantities by the dehydrogenation of ethylbenzene (EB) using promoted iron oxide catalyst with superheated steam.In this case, small amount of carbon dioxide formed as a by-product was known to inhibit the catalytic activity of commercial catalyst. Recently, there have been some reports which carbon dioxide showed positive effects to promote catalytic activities on the reaction over several catalysts.In this study, we attempted to combine the dehydrogenation of EB to STY with the carbon dioxide shift-reaction. The combine reaction (EB + CO2 → STY + H2O + CO) can be considered as one of the ways of using CO2 resources and can yield simultaneously STY and Carbon oxide.Alumina oxide catalysts such as Al2O3, Na2O/Al2O3 and K2O/Al2O3 were prepared by the usual impregnation method with an aqueous solution of NaNO3 and KNO3, and then calcined at 650℃ for 5 h in a stream of air. The reaction condition is 600℃, flow of CO2 38ml/mon and space velocity (EB) 1.28h-1. 相似文献
3.
Modulated
DSC for gas hydrates analysis 总被引:1,自引:0,他引:1
C. Giavarini F. Maccioni Maria Laura Santarelli 《Journal of Thermal Analysis and Calorimetry》2006,84(2):419-424
Modulated DSC has been applied to the study of methane,
ethane and propane hydrates at different hydrate and ice concentrations. The
reversing component of the TMDSC curves, makes it possible to characterize
such hydrates.
Methane and ethane hydrates show the melting-decomposition
peak at a temperatures higher than the ice contained in the sample, while
propane hydrate melts and decomposes at lower temperature than the ice present
in the sample. The hydrate peaks tend to disappear if the hydrate is stored
at atmospheric pressure. Guest size and cavity occupation fix the heat of
dissociation and stability of the hydrates, as confirmed by parallel tests
on tetrahydrofurane hydrates. 相似文献
4.
本文使用详细的化学反应机理模拟了C2H6/O2/N2/AR层流对冲扩散火焰中多环芳烃的生成动力学过程。反应机理包括96种组分的502个基元反应。通过数值计算分析了层流对冲火焰的结构和主要反应物、中间物质和反应产物的浓度变化,并与相关文献的实验结果进行了比较。结果表明,数值模拟在燃烧过程和PAH生成规律上与实验结果是一致的,但在某些组分的定量预报上存在一定的差别。 相似文献
5.
Iron oxide catalyst with spinel structure used for dehydrogenation of ethylbenzene is one kind of important catalyst in petrochemical industry. In this work several series of industrial catalyst were prepared with different components and different manufacturing processes. Mössbauer Spectroscopy has been used to determine the optimal components and the better manufacturing process for spinel structure formation. The results may prove useful for producing the industrial dehydrogenation catalyst with better catalytic property. 相似文献
6.
Dehydrogenation of alcohols into aldehydes and ketones by Ru3(CO)12/PPh3 based homogeneous catalysis has been investigated as an alternative for the classical Oppenauer oxidation. Several catalytic systems have been screened in the Oppenauer-like oxidation of alcohols. A systematic study of various combinations of Ru3(CO)12, mono- and bidentate ligands and hydride acceptors was performed to enable dehydrogenation of primary alcohols to stop at the aldehyde stage. Among many H-acceptors screened, diphenylacetylene (tolane) proved the most suitable judged from its smooth reduction. Electron rich and deficient analogues of tolane have been synthesized and, based on competition experiments between these H-acceptors, a tentative catalytic cycle for the Ru3(CO)12/PPh3-catalyzed dehydrogenations has been proposed. 相似文献
7.
双(十二烷基亚磺酰)乙烷溶剂萃取钯及其机理的研究 总被引:2,自引:0,他引:2
本文研究用双(十二烷基亚磺酰)乙烷萃取钯的性能,在KI存在下从7mol/L盐酸介质中用含有BDSE的氯仿能定量萃取钯,有机的钯可被硫脲或氨溶液反萃继之用TMK-TritonX-100光度法测定,研究了萃取的最佳条件及干扰情况,斜率法测得萃合物组成为Pd:I:BDSE=1:2:1,红外光谱证实萃合物中BDSE的二个亚砜以硫原子与钯配位,萃合物为异位体络合物,提出了选择性萃取分离钯的新方法。 相似文献
8.
L.Late E.A.BlekkanDepartment of Chemical Engineering Norwegian University of Science Technology 《天然气化学杂志》2002,(Z1)
The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550℃ over a VMgO catalyst. Vanadium-magnesium-oxides are among the most selective and active catalysts for the dehydrogenation of propane to propylene. Selectivity to propylene up to about 60% was obtained at 10% conversion, but the selectivity decreased with increasing conversion. No oxygenates were detected, the only by-products were CO and CO2. The reaction rate of propane was found to be first order in propane and close to zero order in oxygen, which is in agreement with a Mars van Krevelen mechanism with the activation of the hydrocarbon as the rate determining step. The activation energy of the conversion of propane was found to be 122±6 kJ/mol. 相似文献
9.
Ibragimov A. G. Khafizova L. O. Zagrebel"naya I. V. Parfenova L. V. Sultanov R. M. Khalilov L. M. Dzhemilev U. M. 《Russian Chemical Bulletin》2001,50(2):292-296
A new method for the synthesis of dialkyl(ethyl)alanes by the reaction of EtAlCl2 with -olefins in the presence of Mg and a catalytic amount of Cp2TiCl2 (Ti(OPri)4, Ti(OBun)4) in THF was developed. 相似文献
10.