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

一个大数量的苯乙烯单体是在这个世界上从乙烯和苯中产生的，然后通过脱氢化给予乙烯苯。3个步骤的过程是当前技术所必需的。这个项目是为了开发一个简单而节能的化学过程。由于这个原因，以太网被用于苯的烷基化，使用各种酸催化剂，如zeolite。However，乙基苯的yield非常小。考虑到从乙烷中产生的乙基转化是困难的，装载了几种金属物种，其中有能力通过测试的铝的脱氢化;与乙烷的苯的烷基化被携带出使用各种沸石催化剂在400 - 550℃的温度范围内。装载在zeolite上的platinum，增强了大量的乙基苯并。在沸石中测试，H-ZSM 5，H-AlMCM 41和H-MCM 22显示催化活性。However， mordenite并没有给乙苯。中度酸强度分布是沸石催化剂的一个关键因素。该反应的最佳催化剂和条件如下：载载铂的H-ZSM 5催化剂含有6.8重量%的Pt，反应温度为500℃，14.2和0.8 mmol h^<-1>·g^<-1>的催化剂，相应地（基于苯的年份为7.3和0.4%）。在用ethane覆盖platinum的H-ZSM 5中， ethene将初始地从ethane覆盖金属platinum形成。然后，烷基化将在H-ZSM 5的酸性位点上进行，并发现了甲基苯的脱氢化，并在碳二氧化物的存在中发现了一种非常高的活性。碳二氧化物推广的还原循环在脱氢反应期间的vanadium氧化物。在哪里，钒酰胺氧化物的晶格氧化物在脱水过程中基本丢失，然后将碳二氧化物重新氧化为低valent的钒氧化物转化为高valency state。

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.