Styrene from benzene and ethylene

Alkenyl halides such as vinyl chloride (H2C=CHC1) do not form carbocations on treatment with aluminum chloride and so cannot be used m Friedel-Crafts reactions Thus the industrial preparation of styrene from benzene and ethylene does not involve vinyl chloride but proceeds by way of ethylbenzene... 

Mark and Wulff A process for making styrene from benzene and ethylene. Developed in Germany in the 1930s. 

FIGURE 2 Manufacture of styrene from benzene and ethylene. 

By 1929, scientists at The Dow Chemical Company were able to devise a method to produce synthetic styrene from benzene and ethylene [1]. This... 

Thus, the industrial preparation of styrene from benzene and ethylene does not involve vinyl chloride but proceeds by way of ethylbenzene. 

Shown below is a portion of a process that produces styrene from benzene and ethylene (see Exercise 2.12). Benzene is recycled to an alkylation reactor and the by-product ethylbenzene is recycled to a dehydrogenation reactor. Stream 2 is 28.0% of stream 1. Also, 97.0% of the ethylbenzene in stream 3 leaves distillation column 2 via stream 4. Calculate the flow rate and composition of stream 5. 

Alkylation. Ethylbenzene [100-41 -4] the precursor of styrene, is produced from benzene and ethylene. The ethylation of benzene is conducted either ia the Hquid phase ia the preseace of a Eriedel-Crafts catalyst (AlCl, BE, EeCl ) or ia the vapor phase with a suitable catalyst. The Moasanto/Lummus process uses an aluminum chloride catalyst that yields more than 99% ethylbenzene (13). More recently, Lummus and Union Oil commercialized a zeoHte catalyst process for Hquid-phase alkylation (14). Badger and Mobil also have a vapor-phase alkylation process usiag zeoHte catalysts (15). Almost all ethylbenzene produced is used for the manufacture of styrene [100-42-5] which is obtained by dehydrogenation ia the preseace of a suitable catalyst at 550—640°C and relatively low pressure, <0.1 MPa (<1 atm). 

The generation of caibocations from these sources is well documented (see Section 5.4). The reaction of aromatics with alkenes in the presence of Lewis acid catalysts is the basis for the industrial production of many alkylated aromatic compounds. Styrene, for example, is prepared by dehydrogenation of ethylbenzene made from benzene and ethylene. 

All of the above high-volume organic chemicals are obtained from petroleum or natural gas. This is why the modern organic chemical industry is frequently referred to as the petrochemical industry. The high-volume status of some of these compounds is due to their use to make others lower on the list. For example, ethylene is used to make ethylene dichloride, which, in turn, is used to make vinyl chloride. Ethyl benzene, made from benzene and ethylene, is used to make styrene. Methyl r-butyl ether is made from methanol and butylene, a captive intermediate for which production data is not available. 

Ethylbenzene has not been separated commercially from Cg aromatics because it cannot be obtained therefrom in high purity as readily as it can be synthesized from benzene and ethylene by alkylation to provide the necessary stock for styrene manufacture. The current shortage of benzene, however, re-establishes interest in separating ethylbenzene from hydroformed stocks. 

Application Production of polymer-grade styrene monomer (SM) from benzene and ethylene. The Lummus/UOP EBOne process is used to alkylate benzene with ethylene to form ethylbenzene (EB). The EB is then dehydrogenated to SM using the Lummus/UOP Classic SM process. 

St3rrene, Phenyl Ethylene.— The first of these hydrocarbons is known as st3rrene. It is obtained from storax a resin found in the plant, Styrax officinalis. It is also present in coal tar. It is related to, and also prepared from, cinnamic acid, an important acid to be considered later. Styrene is a liquid boiling at 140 . Its constitution is proven by its synthesis from benzene and ethylene when a mixture of the two compounds is passed through a red hot tube. 

Styrene is one of the most important substances as a raw material of polymers. In Japan, 1.5 million tons of styrene is produced every year. It is commercially produced by the dehydrogenation of ethylbenzene (equation 1), which is made from benzene and ethylene (equation 2). 

Styrene is produced in the U.S. from benzene and ethylene by a Friedel-Craft reaction that is followed by dehydrogenation over alumina at600 °C. Polystyrene was first prepared in 1839, though the material was confused for an oxidation product of the styrene monomer. Today, polystyrene is produced in very large quantities and much is known about this material. 

Polystyrene is made by bulk or suspension polymerization of styrene. It is commonly available in crystal, high impact, and expandable grades. Its major characteristics include transparency, ease of coloring and processing, and low cost. Styrene monomer is produced from benzene and ethylene. 

Ethylbenzene is the key intermediate in the manufacture of styrene, one of the most important industrial monomers. Almost all ethylbenzene is synthesized from benzene and ethylene. 

For example, as the result of a great effort in Europe in the fifties, there was a switch from coal to oil as the feedstock. Only the petrochemical industry was able to supply the increasingly large amounts of raw materials for plastics. This is particularly true of benzene and ethylene, the two starting materials for styrene monomer and polystyrene. Ever-growing capacities and plants supplied these chemicals up to 1973 at ever lower prices which brought down the price of polystyrene and opened up further fields of applications. 

The alkene arylation reaction has been extensively studied by Moritani and coworkers462 and by Heck.463 An interesting application of this chemistry is the synthesis of styrene from the oxidative coupling of benzene and ethylene (equation 189).464... 

Other methods, such as the direct reaction of benzene and ethylene (Fig. 2) or from pyrolysis gasoline (Fig. 3) are also used to manufacture styrene. 

Example 2 Synthesis of a styrene process. Styrene, the monomer of polystyrene, has enjoyed strong market growth over the past two decades. It is prepared starting with benzene and ethylene which react to form ethylbenzene the ethylbenzene is dehydrogenated to yield styrene. Further information about styrene manufacture, properties, and uses is available. 3 In this example, the steps involved in synthesizing a process to produce styrene from ethylbenzene will be illustrated. The procedure followed is analogous to that followed by the PIP program. 

In fact, the standard in the industry is that styrene production is integrated from benzene and the ethylene raw material (e.g. propane) through styrene (and propylene oxide for the second process). Styrene production is part of an integrated petrochemical process. 

Thermal cracking of ethane, propane, butane, naphthas, gas oils, and/or vacuum gas oils is the main process employed for the production of ethylene and propylene butadiene and benzene, toluene, and xylenes (BTX) are also produced. Thermal cracking of these hydrocarbons is also called pyrolysis of hydrocarbons. Ethylene is the organic chemical produced worldwide in the largest amoimts and has been called keystone to the petrochemical industry. This technology is well documented in the literature. Somewhat similar thermal cracking processes are used to produce vinyl chloride monomer (VCM) from ethylene dichloride (EDQ, styrene from ethylbenzene, and allyl chloride from propylene dichloride (PDC). Production of charcoal and coke from wood and coal is actually a pyrolysis process, but it is not discussed here. 

Styrene was first reported by Neuman in the late eighteenth century from storax. Storax is a balsam derived from the trees of Liquamber orientalis which are native to Asia Minor. His experiments were confirmed years later. In 1839 Simon named the product "styrol" and noted that after a few months it became jellylike. In 1841 Gerhardt and Cahours arrived at the correct formula, CgHg, and prepared the dibromlde derivative. In 1845 Blyth and Hofmann confirmed that a solid mass resulted when styrene was heated. Additional work was done in which styrene was prepared from cinnamic acid by decarboxylation. In 1866 Berthelot prepared styrene from the reaction of benzene and ethylene in a hot tube. Thus, at the turn of the century the following chemistry was known ... 

---