Ethylbenzene by Alkylation of Benzene with Ethylene

Alkylation of benzene with ethylene to give ethylbenzene according to Equation 3, an example of the classical Friedel-Crafts chemistry, is one of the largest tonnage C-C bond forming processes. 

This is one of the few metal catalyzed processes involving a non-transition metal where conventional chemistry has been transferred to a large commercial scale. The world production of this intermediate to styrene (Section 3.9.3) amounts to ca. 27 Mt/a. 

An ion pair of the type, H AlCl4, is believed to be the actual catalyst in the liquid-phase process operating at ca. 90 °C. As is well known in electrophilic aromatic substitution, electron-releasing substituents favour alkylation thus ethylbenzene can undergo further alkylation to diethylbenzenes. To limit overalkylation, benzene must be used in large excess. The peralkylated benzenes, however, can be recycled to obtain ethylbenzene by exchange with 

The requirements of industrial processes (easy separation of catalysts from products, low levels of corrosion and of polluting fluids) have led to the development of heterogeneous catalysts that avoid the presence of corrosive or undesirable species in solution and in the products, in contrast to homogeneous processes. Several types of zeolites can be used for both the liquid- and the gas-phase processes, such as ZSM-5, MCM-22, Y and Beta (Appendix 2). 

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All lation. An exceUent example of alkylation is the Mobil-Badger process, which uses ZSM-5-type zeoHte to produce ethylbenzene by alkylation of benzene with ethylene (12,40) ... 

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