共查询到20条相似文献,搜索用时 109 毫秒
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基于链段法定义了对苯二甲酸和1,4-丁二醇聚合生成聚对苯二甲酸丁二醇酯(PBT)的反应体系的各组分和基团,明确了体系中的反应类型有酯化反应、酯交换反应、酯基降解反应、1,3-丁二烯生成反应、四氢呋喃生成反应,通过链段浓度表示了各个反应的反应速率及聚合物性质,并采用Aspen Polymer工艺流程模拟软件建立了PBT三... 相似文献
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用择形催化剂XC-90催化α-蒎烯异构化反应,考察了反应时间、反应温度对反应结果的影响,研究了该反应的动力学,求出了反应的表观活化能、频率因子和反应级数,建立了反应速率常数与温度的关系式 相似文献
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提出了隔壁反应精馏合成碳酸甲乙酯的新工艺,除考虑碳酸二甲酯与乙醇酯交换反应外,还考虑了碳酸二甲酯与碳酸二乙酯反歧化反应的影响,并集成上述反应于一台隔壁反应精馏塔中,优化了碳酸甲乙酯的生产过程。首先,进行了碳酸二甲酯与碳酸二乙酯反歧化反应动力学实验,建立反应动力学模型,并验证了该工艺流程中此模型计算结果的可靠性。然后,运用Aspen Plus对隔壁反应精馏新工艺进行了流程模拟和优化设计,分别确定了酯交换反应段、反歧化反应段、产品精馏段和公共提馏段的理论塔板数,最佳进料位置、回流比等主要操作参数。隔壁反应精馏新工艺与常规反应精馏三塔工艺相比,新工艺将塔釜产品碳酸二乙酯返回隔壁塔内,增加了反歧化反应区,显著提高了碳酸甲乙酯选择性和收率,避免了低价值副产物碳酸二乙酯的产生,并有效减少了设备投资和运行能耗。 相似文献
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《化学工程》2016,(7):30-33
利用基团贡献法估算了烷基胺类化合物与CO羰基化反应生成N-烷基甲酰胺的标准生成焓、标准熵和摩尔定压热容,对反应体系的热力学性质进行计算,得到不同反应温度下的反应焓变、吉布斯自由能变以及反应平衡常数等热力学数据。分析了反应的方向与限度,考察了温度对反应焓变、吉布斯自由能变和反应平衡常数的影响,比较了热力学数据随反应物分子结构的变化规律。结果表明:在323 K到473 K的温度区间内,文中涉及的烷基胺羰基化反应均为放热反应,随反应温度的升高,反应由自发向右进行转变为非自发反应。烷基胺N原子上取代基个数和结构的不同对反应热、反应方向与限度均产生影响。 相似文献
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Kian Fei Yee Eng-Poh Ng Abdul Rahman Mohamed Farook Adam 《Chemical Engineering Communications》2016,203(10):1385-1394
Most of the conventional catalysts exhibited limitations in catalyzing etherification reactions. In this study, functionalized multi-walled carbon nanotube (F-CNT) catalyst containing Lewis acid sites were prepared via functionalization with sulfuric acid and the catalytic performances in the etherification of tert-butyl alcohol (TBA) with ethanol were investigated. Characterization of F-CNTs with thermogravimetric analysis, Raman spectroscopy, Fourier transform-infrared spectroscopy, pyridine adsorption, temperature-programmed desorption of ammonia and nitrogen adsorption were performed to correlate the characteristics with the catalytic performances. The catalyst showed a high catalytic performance and high selectivity in the etherification reaction. The best reaction conditions obtained consist of 4 h of reaction time at 140°C, an ethanol:TBA molar ratio of 2:1 and a catalyst loading of 3 wt%. The best conversion of TBA and TBA selectivity toward ethyl tert-butyl ether (ETBE) were 64% and 68%, respectively. No significant degradation of the catalytic performance was observed after four consecutive reactions and the catalyst was easily regained after regeneration. A mechanism for the etherification reaction was also proposed. 相似文献
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The reactions between a multifunctional epoxy resin, tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM) and a monofunctional amine, methylaniline (mAnil) are studied. Due to the existence of a tertiary amine catalytic center within the TGDDM molecule, the etherification reaction during cure of TGDDM is usually more significant than in other epoxide systems. The importance of this reaction relative to the amine addition reactions is investigated. In situ near-infrared spectroscopy is used to obtain kinetic data during the cure reactions. The reaction rate constants are calculated from linear regression analysis for both amine addition and etherification reactions based on the reaction mechanisms proposed. Arrhenius relationships are observed for all the reaction rate constants involved. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:895–901, 1998 相似文献
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新杀虫杀螨剂氟虫脲的合成陈英奇,王胜鹏,洪朝 (浙江大学化工系,杭州310027)关键词:氟虫脲,合成1前言苯甲酰苯基脲类化合物是日趋重要的一类杀虫剂,它藉干扰几丁质合成杀死害虫,目前已有大量该类化合物被合成,不少已经商品化[1]。氟虫脲(I)(通用?.. 相似文献
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It has been shown that 6-chloro sugar derivatives are thermally less stable than the corresponding unsubstituted carbohydrates. When heated, they generate hydrogen chloride which catalyzes a series of heterolytic reactions including transglycosylation, dehydration, inter- and intramolecular etherification, and condensation. The latter products are ultimately carbonized through free-radical reactions producing large amounts of char. 相似文献
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我国聚乙烯醇改性技术进展 总被引:3,自引:0,他引:3
综述了国内聚乙烯醇改性技术的进展情况.改性方法包括:共聚、共混和聚合物后反应(涉及醚化、醇化、缩醛化、交联、降解及表面改性等)三大类.较为详细地介绍了聚乙烯醇纤维的改性.并对我国聚乙烯醇工业的发展进行了展望. 相似文献
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The reaction kinetics for the cure of epoxy resins with imidazoles were determined from Fourier transform infrared spectroscopy and differential scanning calorimetry studies. The diglycidyl ether of bisphenol A and phenyl glycidyl ether were cured with various concentrations of 2-ethyl-4-methyl-imidazole ranging from 4.0 to 100.0 mol %. The first step in the curing process is the formation of epoxide/imidazole adducts. These adducts initiate the etherification reaction which crosslinks the resin. The kinetics were determined and confirmed for both the adduct and the etherification reactions as a function of the imidazole concentration. A model was developed and used to predict the concentrations of the unreacted epoxide groups and the reaction products for a wide range of imidazole concentrations and cure temperatures. 相似文献