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Development of catalyst for the synthesis of styrene from ethane and benzene

乙苯合成苯乙烯催化剂的研制

基本信息

批准号：
11650811
负责人：
SUZUKI Toshimitsu
金额：
$ 2.37万
依托单位：
Kansai University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

A large quantity of styrene monomer was produced in the world from ethylene and benzene to give ethylbenzene followed by dehydrogenation. 3 step processes were required in the current technology. This project was planned to develop a simple and energy saving chemical process. For this, ethane was used for the alkylation of benzene using various acid catalysts such as zeolite. However, yield of ethylbenzene was very small. Considering that formation of ethyl cation from ethane is difficult, loading of several metal species which are capable of dehydrogenation of alkane was examined.Alkylation of benzene with ethane was carried out using various zeolite catalyst at temperature ranges of 400 to 550℃. Loading of platinum onto zeolite enhanced yield of ethylbenzene greatly. Among zeolite tested, H-ZSM5, H-AlMCM41, and H-MCM22 showed catalytic activities. However, mordenite did not give ethylbenzene. Moderate acid strength distribution is the key factor of zeolite catalyst. Optimum catalyst and conditions for this reaction is as follows :Platinum-loaded H-ZSM5 catalyst containing 6.8 wt % Pt, at the reaction temperature of 500℃, afforded ethylbenzene and styrene formation rates of 14.2 and 0.8 mmol h^<-1>・g^<-1> of catalyst, respectively (benzene-based yields 7.3 and 0.4 %). In the alkylation of benzene with ethane over platinum-loaded H-ZSM5, ethene would be initially formed from ethane over the metallic platinum. Then the alkylation would proceed over the acid sites of H-ZSM5.Dehydrogenation of ethylbenzene was investigated, and found that magnesium oxide-loaded vanadium oxide exhibited very high activity in the presence of carbon dioxide. Carbon dioxide promoted redox cycle of vanadium oxide during dehydrogenation reaction. Where lattice oxygen of vanadium oxide was gradually lost during dehydrogenation, then carbon dioxide reoxidized low valent vanadium oxide to higher valency state.

世界上大量苯乙烯单体的生产都是以乙烯和苯为原料，经脱氢制苯乙烯。在当前技术中需要3步工艺。本项目旨在开发一种简单、节能的化工工艺。为此，乙烷用于使用各种酸催化剂如沸石的苯的烷基化。但是，产率很低。考虑到乙烷难以形成乙基阳离子，考察了几种具有烷烃脱氢活性的金属物种的负载情况，在400 ~ 550℃温度范围内，用不同的沸石催化剂进行了苯与乙烷的烷基化反应。沸石负载铂大大提高了产率。在所测试的沸石中，H-ZSM 5、H-AlMCM 41和H-MCM 22显示出催化活性。然而，丝光沸石没有给出。适中的酸强度分布是分子筛催化剂的关键因素。最佳催化剂和反应条件为：Pt含量为6.8wt%的H-ZSM 5催化剂，在500℃下，苯乙烯和乙苯的生成速率分别为14.2和0.8mmol·h<-1>·g·（<-1>催化剂），苯收率分别为7.3%和0.4%。在负载铂的H-ZSM 5催化剂上苯与乙烷的烷基化反应中，乙烷在金属铂上首先生成乙烯。研究了氧化镁负载的钒氧化物在二氧化碳存在下的脱氢反应，发现氧化镁负载的钒氧化物在二氧化碳存在下表现出很高的催化活性。在脱氢反应中，二氧化碳促进了氧化钒的氧化还原循环。氧化钒在脱氢过程中逐渐失去晶格氧，然后二氧化碳将低价氧化钒再氧化成高价态。