【作者】 王莉；

【导师】 罗国华；

【作者基本信息】 北京化工大学 ， 化学工艺， 2011， 硕士

【摘要】 苯的乙基化是制备乙苯的主要方法,工业上大多采用乙醇或乙烯为烷基化剂,在固体酸催化作用下直接烷基化,但较少有用氯乙烷为烷基化剂与苯烷基化反应制乙苯,因此论文分别以氯铝酸型离子液体、HZSM-5及改性HZSM-5沸石分子筛为催化剂,开展了苯与氯乙烷烷基化制乙苯反应的研究,并将性能评价和物化表征相结合,对催化剂的催化性能差异进行了探讨。论文首先以氯铝酸型离子液体为催化剂(盐酸三乙胺为阳离子),对苯与氯乙烷烷基化制乙苯的反应条件从阴离子种类、加料方式、n(AICl3) /n ([Et3NH]Cl)、反应温度、n(苯)/n(氯乙烷)、离子液体用量、反应时间及离子液体的重复使用性等方面进行了系统的考察。结果表明,加料方式对苯转化率及乙苯选择性有影响,在相同的反应条件下,第Ⅱ种加料方式与第Ⅰ种加料方式相比,所得的苯转化率和乙苯选择性较高。反应温度升高,苯转化率升高,乙苯选择性降低；增加n (AICl3) /n ([Et3NH]Cl)、n(苯)/n(氯乙烷)、离子液体用量,有利于提高乙苯的选择性。在适宜的反应条件下,离子液体用量为苯和氯乙烷总质量的10%,n (AICl3) /n ([Et3NH]Cl)为2,反应温度为70℃,n(苯)/n(氯乙烷)为10,反应时间30min,苯的转化率达到9.48%,乙苯的选择性达到93.65%,离子液体循环使用10次后仍能基本保持新鲜催化剂的性能,对于使用过的催化剂,通过补加AICl3的方法可恢复催化剂的活性,反应过程中只有少量的二乙苯以及极少量的三乙苯,未有二甲苯异构体生成。其次,论文以HZSM-5为催化剂,系统的考察了苯与氯乙烷烷基化制乙苯的反应条件。结果表明,以硅铝比为25的HZSM-5为催化剂催化反应的适宜反应条件为：反应温度300-340℃,7n(苯)/n(氯乙烷)为8-10,质量空速为4-6 h-1,在此条件下,催化剂催化苯与氯乙烷烷基化制乙苯具有较好的催化活性。最后,以硼、磷、镁改性的HZSM-5(硅铝比25)为催化剂,在相同的反应条件下,即反应温度320℃,,n(苯)/n(氯乙烷)为10,质量空速为4 h-1,催化的苯与氯乙烷烷基化反应苯转化率均比未改性前降低,乙苯选择性均得到提高,负载5%硼,乙苯选择性可达99.27%,磷的负载量为3%时,乙苯选择性为97.92%,负载1%镁,乙苯的选择性为96.98%。结合性能评价和XRD、TPD、红外吡啶、BET等表征手段,发现改性后的HZSM-5沸石分子筛总酸量均较未改性前有所下降,酸强度也有所减少,比表面积和孔容均变小,说明分子筛催化剂的表面酸性是影响苯转化率和乙苯选择性的主要因素。更多还原

【Abstract】 Ethylation of benzene is the main method to form ethyl benzene, in industry, ethanol or ethylene is mostly used as alkylating agents, catalyzed by solid acid to alkylate directly, but less used ethyl chloride as alkylating agent to alkylate with benzene to ethyl benzene, therefore the alkylation reaction process of benzene with ethyl chloride to form ethylbenzene was investigated over chloroaluminate ionic liquid, HZSM-5 zeolites and modified HZSM-5 zeolites, and the performance differences among these catalysts were also investigated combining the catalytic reaction experiments and the characterization of the catalysts.Firstly, chloroaluminate ionic liquid was used as catalyst, and its catalytic performance on the alkylation of benzene with ethyl chloride was studied experimentally.The effect of sunch influencing factors was investigated as the anion of ionic liquids, feeding methods, the molar ratio of AlCl3 to [Et3NH]Cl, temperature, the molar ratio of benzene to ethyl chloride, the amount of ionic liquid, time and the regeneration approach of the used ionic liquid catalyst was studied.The results suggested that the feeding methods impact on the conversion of benzene and selectivity of ethyl benzene,under the same conditions, compared feeding method II to feeding method I, the former conversion of benzene and selectivity of ethyl chloride is higher.Increasing the temperature can helpt to increase the conversion of benzenen, but decrease the selectivity of ethyl benzene.It helps to increase the selectivity of ethyl benzene by increasing the molar ratio of AlCl3 to [Et3NH]Cl, the amount of catalyst and molar ratio of benzene to ethyl chloride.At optimal conditions,that is,10wt% of catalyst with benzene and ethyl chloride,2:1 of molar ratio of AICl3 to [Et3NH]Cl,70℃,10:1of molar ratio of benzene to ethyl chloride, the conversion of benzene can reach 9.48%, and the selectivity of ethyl benzene can reach 93.65%. The activity of the catalyst can be basically remained after ten times reuse. For the used ionic liquid, its catalytic activity can be recovered via adding some extra AlCl3. In the process of the whole experiment, there is a small amount of diethylbenzene and rarely triacetate benzene generated, and no xylene isomers generated.Secondly, the effect of reaction conditions on the alkylation process for ethylbenzene synthesis over the HZSM-5 zeolite catalyst was systematically discussed and the optimal reaction conditions were researched. The result shows that the appropriate operating conditions are as follows:temperature was 300～340℃, the molar ratio of benzene to ethyl chloride was 8～10 and the weight hourly space velocity was 4～6h-1. Finally, the modified HZSM-5 zeolite used as catalysts, under the same condition of unmodified HZSM-5 zeolite, that is,320℃,10:1of molar ratio of benzene to ethyl chloride,4h-1 of the weight hourly space velocity, the conversion of benzene was lower than unmodified HZSM-5 zeolite’s, but the selectivity of ethyl benzene was higher.5% boron modified HZSM-5, it’s selectivity of ethyl benzene was 99.27%,3% phosphorus modified HZSM-5 was 97.92%, and 1% magnesium was 96.98%. Combining the performance evaluation (activity, selectivity) and the characterization of the catalysts (XRD, TPD, FT-IRand BET), showed that the total acid quantity of modified HZSM-5 was smaller than unmodified HZSM-5, simultaneously the acid strength slightly decreased, and the surface area and pore volume decreased too, the surface acidity of zeolite catalyst is the main factor which impact on the conversion of benzene and the selvctivity of ethyl benzene.更多还原