Editing Styrene (section)

===From ethylbenzene===
The vast majority of styrene is produced from [[ethylbenzene]],<ref name="ullstyrene">{{Ullmann |first1=Denis H. |last1=James |first2=William M. |last2=Castor |title=Styrene |year=2007 |doi=10.1002/14356007.a25_329.pub2}}</ref> and almost all ethylbenzene produced worldwide is intended for styrene production. As such, the two production processes are often highly integrated. Ethylbenzene is produced via a [[Friedel–Crafts reaction]] between benzene and [[ethene]]; originally this used [[aluminum chloride]] as a [[catalyst]], but in modern production this has been replaced by [[zeolite]]s.

====By dehydrogenation====
Around 80% of styrene is produced by the [[dehydrogenation]] of [[ethylbenzene]]. This is achieved using superheated steam (up to 600&nbsp;°C) over an [[iron(III) oxide]] catalyst.<ref>{{cite journal |last1=Lee |first1=Emerson H. |title=Iron Oxide Catalysts for Dehydrogenation of Ethylbenzene in the Presence of Steam |journal=Catalysis Reviews |date=13 December 2006 |volume=8 |issue=1 |pages=285–305 |doi=10.1080/01614947408071864}}</ref> The reaction is highly [[endothermic]] and reversible, with a typical yield of 88–94%.

:[[File:StyreneProduction.svg|500px]]

The crude ethylbenzene/styrene product is then purified by distillation. As the difference in boiling points between the two compounds is only 9&nbsp;°C at ambient pressure this necessitates the use of a series of distillation columns. This is energy intensive and is further complicated by the tendency of styrene to undergo thermally induced polymerisation into polystyrene,<ref name=autopoly1>{{cite journal |last1=Khuong |first1=Kelli S. |last2=Jones |first2=Walter H. |last3=Pryor |first3=William A. |last4=Houk |first4=K.N. |title=The Mechanism of the Self-Initiated Thermal Polymerization of Styrene. Theoretical Solution of a Classic Problem |journal=[[Journal of the American Chemical Society]] |date=February 2005 |volume=127 |issue=4 |pages=1265–1277 |doi=10.1021/ja0448667 |pmid=15669866|bibcode=2005JAChS.127.1265K }}</ref> requiring the continuous addition of [[polymerization inhibitor]] to the system.

====Via ethylbenzene hydroperoxide====
Styrene is also co-produced commercially in a process known as POSM ([[Lyondell Chemical Company]]) or SM/PO ([[Royal Dutch Shell|Shell]]) for styrene monomer / [[propylene oxide]]. In this process, ethylbenzene is treated with oxygen to form the [[ethylbenzene hydroperoxide]]. This hydroperoxide is then used to oxidize [[propylene]] to propylene oxide, which is also recovered as a co-product. The remaining 1-phenylethanol is dehydrated to give styrene:

: [[File:Styrol synthesis.svg|450px|Synthesis of styrene]]