Synthesis of novel electron donors and their application to propylene polymerization

A series of electron donors,including 1,1-cyclopentanecarboxylic acid diethyl ester (CPCADEE),1,1cyclopentanedimethanol acetic diester (CPDMAD),1,1-biethoxymethyl pentane (BEMP),2,2-diethyl diethylmalonate (DEDEM)and 2,2-diethyl-1,3-propanediol acetic diester (DEPDADE),were synthesized by diethyl malonate (DEM).The purities and structures of the above products were characterized by gas chromatography (GC) and gas chromatography-mass spectrometer (GC-MS),respectively.Furthermore,the possible optimal three-dimensional structures of these donors were simulated by means of Gaussian 03 and Chem 3D.Then these electron donors were coordinated with tetrachloro titanium (TiCl 4) and chloride magnesium (MgCl 2)to obtain the catalysts for the polymerization of propylene.The catalytic activities and properties of polypropylene are greatly improved by adding external donor(ED) when CPCADEE or DEPDADE is used as internal donor(ID).However,when BEMP was used as ID,the highest catalytic activity is obtained without adding ED,which can reduce production costs and simplify catalytic synthesis.The experiments indicate that BEMP has the shortest distance of oxygen atoms and the highest electronegativity.     

浅谈如何提高天然气轻烃回收装置收率

目前我国轻烃回收普遍来说效率较低,如果要从低压低回收的轻烃收率状态向高收率、低能耗的方向发展,且对原装置不做特别大的改动,这是本文研究的课题。本文以大庆油田的某套轻烃回收装置为对象,通过模拟计算研究了温度、压力对轻烃收率的影响,分析装置所存在的问题,提出具体的工艺技术改造措施。结果表明:在对原装置不做重大改造的前提下,通过回收外输干气冷量,增加水冷设备等,轻烃收率大幅提高,实验证明该套改造方案合理可行。     

丙烯冷凝器换热管断裂的原因分析

本文对一起丙烯冷凝器换热管断裂的原因进行了分析,指出局部[CL]ˉ浓度过高产生的应力腐蚀是换热管断裂的主要原因。     

吡啶制备的实验研究

α-甲基吡啶在一定温度下经高锰酸钾氧化，再在酸性条件下蒸馏、脱羧。可制备产品吡啶．实验采用了对比实验的方法．重点探讨了反应时间、反应温度及氧化剂用量对吡啶收率的影响．在氧化剂高锰酸钾用量为原料α-甲基吡啶65％的配比下。120℃反应4小时制备吡啶，收率高达67％，该制备方法操作安全简便，产品容易分离。     

问溴苯甲醚合成工艺探析

根据反应机理和合成工艺比较，研制了以间氨基苯酚为原料，经重氮化、Sandmeyer反应、酸解和醚化反应合成问溴苯甲醚的工艺过程，并探析了有关工艺参数，总收率54％。     

降血脂药吉非罗齐的合成

以对二甲苯为起始原料，经五步反应合成吉非罗齐，总收率为２２．７％．其中Ｏ－烷基化采用固－液相转移催化技术，对重氮盐的水解和Ｃ－烷基化的工艺条件进行了改进，收率明显提高，合成路线原料易得，操作方便，收率稳定．     

综合知识训练(二)

做题不能追求数量,而要讲究质量,要学会以点带面,多角度理解,只有这样才能跳出题海的怪圈.选择好题,选择成功!为此,我们特推荐以下习题,希望同学们能够融会贯通,学以致用,从多种角度去分析思考问题,积极探索解题规律,探索出获得最优解法的途径.     

硫酸法钛白生产中水洗用水节水工艺控制

硫酸法钛白生产中水洗工序要耗用大量的水来洗涤偏钛浆中的可溶性杂质,通过合理安排工艺可以有效地节约水洗工艺用水,节水量可达50%,起到节水减排效果。     

提高柴汽比和轻油收率的几种措施

简要介绍了提高柴汽比和轻油收率的几种措施.     

Modeling and optimization of catalytic dehydration of ethanol to ethylene using central composite design

The central composite design in the modeling and optimization of catalytic dehydration of ethanol to ethylene was performed to improve the ethylene yield. A total of 20 experiments at random were conducted to investigate the effect of reaction temperature, Si/Al ratios of H-ZSM-5 catalyst and liquid hourly space velocity (LHSV) on the ethylene yield. The results show that the relationship between ethylene yield and the three significant independent variables can be approximated by a nonlinear polynomial model, with R-squared of 99.9% and adjusted R-squared of 99.8%. The maximal response for ethylene yield is 93.4% under the optimal condition of 328 °C, Si/Al ratio 85, and LHSV 3.8 h⁻¹.