Dehydrogenation de l'ethylbenzene pour obtenir le stirene

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Dehydrogenation of ethylbenzene to styrene

Table of Contents 1.
 Introduction
 1.1.
 History
 1.2.
 Uses
 1.3.
 Main
producers
 1.3.1.
 Styrene
market
 1.4.
 Regulatory
treatment
of
styrene
 1.4.1.
 European Union Risk Assessment Review
 2.
 Properties
 2.1.
 Physical
properties
 3.
 Production
methods
 3.1.
 Styrene­Propylene
oxide
process
 3.2.
 Styrene
via
benzene
and
ethane
 3.3.
Dehydrogenation
of
ethylbenzene
 3.3.1.
 Chemistry of ethylbenzene dehydrogenation
 3.3.2.
 Steam in ethylbenzene dehydrogenation
 3.3.3.
 Catalysts
 3.3.4.
 Catalyst promoters
 3.3.5.
 Isothermal dehydrogenation
 3.3.6.
 Adiabatic dehydrogenation
 3.3.7.
 Comparison between isothermal and adiabatic dehydrogenation
 3.3.8.
 By-products in ethylbenzene dehydrogenation
 3.3.9.
 Purification of styrene
3.3.10.
 Economical
analysis
 Works
Cited
 2
 2
 3
 5
 6
 7
 7
 8
 8
 9
 10
 11
 12
 12
 14
 15
 17
 18
 19
 21
 21
 22
 24
 26




1


Dehydrogenation of ethylbenzene to styrene

1. Introduction
1.1. History

Styrene [C6H5-CH=CH2], also known as phenylethylene, vinylbenzene, styrol, or cinnamene is one of the most important monomers in modern petrochemical industry. It occurs naturallyin small quantities in some plants and foods. A study published in the Journal of Agricultural and Food Chemistry in 1994 showed that concentrations of styrene are present in cinnamon, beef, coffee beans, peanuts, wheat, oats, strawberries, and peaches. It was isolated for the first time in the nineteenth century by steam distillation of styrax, a balsam obtained from the trunk of a tree calledLiquidambar orientalis. Although it was known to polymerize, no commercial applications were attempted for many years because the polymers were brittle and readily cracked. InteressenGemeinschaft Farbenindustrie AG in Germany and Dow Chemical in the United States achieved the development of the commercial processes for the manufacture of styrene based on dehydrogenation of ethylbenzene in the 1930s.Several plants were built in Germany before World War II to produce styrene, primarily for making synthetic rubber. It also became a material of strategic importance in the United States when the supply of natural rubber from South Asia was cut off from the Allied countries’ access, and large-scale plants were built. After the war the demand of styrene continued to grow but its main use shiftedfrom synthetic rubber to polystyrene. The production of styrene in the United States increased from 2.0 million metric tones in 1970 to 5.8 million tones in 2004. Western Europe and Japan showed also a very rapid growth and this is due to several important factors: it is a liquid that can be handled easily and safely, it can be polymerized and copolymerized under a variety of conditions by commonmethods of plastics technology to a large number of polymers of different properties and applications, polystyrene is easy to extrude and mold and is one of the least expensive thermoplastics volumetrically, the raw materials benzene and ethylene are produced in very large quantities in refineries and can be supplied to styrene plants through pipe-lines, the manufacturing technologies are efficientand plants can be built on a large scale to produce styrene at low cost.(Kirk-Othmer 2004, Ullmann n.d.)



2


Dehydrogenation of ethylbenzene to styrene

1.2. Uses

Styrene is mainly used in the manufacture of homopolymers and copolymers. These include polystyrene (PS), expandable polystyrene (EPS), styrene copolymers such as acrylonitrile-butadiene-styrene (ABS) resins,styrene-acrylonitrile (SAN) and styrene-butadiene (SB) latexes, styrene-butadiene rubber (SBR) and unsaturated polyester resins. Approximately 65 % of the styrene produced goes into polystyrene. Packaging applications such as containers, closures, lids and vending cups are the major end use for PS. The remaining markets include construction; electrical and electronic parts; domestic appliances and housings;...
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