Alkylation of benzene with ethylene

The EB present in recovered mixed xylenes is largely converted to xylenes or benzene. The EB used to make styrene is predominately manufactured by the alkylation of benzene with ethylene. 

For example, ia the iadustriaHy important alkylation of benzene with ethylene to ethylbenzene, polyethylbenzenes are also produced. The overall formation of polysubstituted products is minimized by recycling the higher ethylation products for the ethylation of fresh benzene (14). By adding the calculated equiUbrium amount of polyethylbenzene to the benzene feed, a high conversion of ethylene to monoethylbenzene can be achieved (15) (see also... 

Styrene is manufactured from ethylbenzene. Ethylbenzene [100-41-4] is produced by alkylation of benzene with ethylene, except for a very small fraction that is recovered from mixed Cg aromatics by superfractionation. Ethylbenzene and styrene units are almost always installed together with matching capacities because nearly all of the ethylbenzene produced commercially is converted to styrene. Alkylation is exothermic and dehydrogenation is endothermic. In a typical ethylbenzene—styrene complex, energy economy is realized by advantageously integrating the energy flows of the two units. A plant intended to produce ethylbenzene exclusively or mostly for the merchant market is also not considered viable because the merchant market is small and sporadic. 

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) ... 

Ethylbenzene can also be produced by catalytic alkylation of benzene with ethylene. Benzene is alkylated with ethylene in a fixed bed alkylator. An excess of benzene is used to suppress the formation of di- and triethyl- benzenes. The excess benzene is removed from the alkylate by fractionation and recycled to the alkylator. The ethylbenzene is separated from the polyalkylated benzenes which are in turn fed to a separate reactor. Here benzene is added to convert the polyalkylated benzenes to monoethylbenzene by transalkylation. 

Ethylbenzene (C6H5CH2CH3) is one of the Cg aromatic constituents in reformates and pyrolysis gasolines. It can be obtained by intensive fractionation of the aromatic extract, but only a small quantity of the demanded ethylbenzene is produced by this route. Most ethylbenzene is obtained by the alkylation of benzene with ethylene. Chapter 10 discusses conditions for producing ethylbenzene with benzene chemicals. The U.S. production of ethylbenzene was approximately 12.7 billion pounds in 1997. Essentially, all of it was directed for the production of styrene. 

The main process for producing EB is the catalyzed alkylation of benzene with ethylene ... 

Fig. 8-1 Alkylation of benzene with ethylene to form ethylbenzene...

In alkylation of benzene with both ethylene and propylene di- and polyalkylates are also formed. In alkylation with propylene 1,2,4,5-tetraisopropylbenzene is the most highly substituted product steric requirements prevent formation of penta-and hexaisopropylbenzene. On the other hand, alkylation of benzene with ethylene readily even yields hexaethylbenzene. Alkylation with higher alkenes occurs more readily than with ethylene or propylene, particularly when the alkenes are branched. Both promoted metal chlorides and protic acids catalyze the reactions. 

Alkylation of benzene with ethylene gives ethylbenzene,283,284,308,309 which is the major source of styrene produced by catalytic dehydrogenation. High benzene ethylene ratios are applied in all industrial processes to minimize polyethylation. Polyethylbenzenes formed are recycled and transalkylated with benzene. Yields better than 98% are usually attained. Reactants free of sulfur impurities and water must be used. 

Desorption of similar products from cumene- and propylene-deactivated parent H-mordenite is a result analogous to that of Venuto and Hamilton (3). They found that deactivation of rare earth X (REX) faujasite by alkylation of benzene with ethylene to ethylbenzene resulted in trapped products similar to those for deactivation with ethylene alone. 

ReCl5 has been found to act as a Friedel-Crafts catalyst for the alkylation of benzene with ethylene. Ethylbenzene, x-butylbenzene and hexaethylbenzene were formed.612 When propylene was used in place of ethylene, cumene and di-, tri- and tetra-isopropylbenzenes were obtained.613 Ethylbenzene and anisole were also alkylated with ethylene. A carbonium ion mechanism was proposed, in some cases with dimerization of ethylene preceding alkylation. 

On the other hand, the Nation resin in its acidic form (Nafion-H) shows high activity in a variety of electrophilic reactions. Gas-phase alkylation of benzene with ethylene and propylene in a flow system proceeds at temperatures as low as 110°C over Nafion-H (Table 5.10). 

Over 90 percent of all ethylbenzene is produced by alkylation of benzene with ethylene in the presence of an acidic catalyst such as aluminum chloride or an acidic zeolite. Figure 10.13 shows a liquid phase alkylation process with zeolite catalyst. 

The production of butadiene monomer is discussed below in polybutadiene section Polybutadiene. The largest volume of styrene is produced by the alkylation of benzene with ethylene to give ethyl benzene, which is then dehydrogenated to give styrene.27... 

Abstract Alkylation of benzene with ethylene over Y-type zeolite has been carried out under supercritical conditions. Two aspects of the reaction have been paid attention to slowing down the deactivation rate and decreasing the by product selectivity. Experiments have revealed the existence of some coke precursors that are partly removed from the catalyst surface. By product xylenes are decreased and are explained due to high diffiisivity in the supercritical fluid. 

As another aspect in the alkylation of benzene with ethylene, side reaction selectivity is also a key problem In this present case, xylenes are the major by-products of the reaction. The main products ethylbenzene and the by-products xylene are isomers with very close boiling points, which cause great difficulty in separation xylenes from ethylbenzene. 

Based on the above experimental results and analysis, the main conclusions concerning the SCFP alkylation of benzene with ethylene over Y-type zeolite can be summarized as follows ... 

Friedel-Crajts alkylations are widely used in both the bulk and fine chemical industries. For example, ethylbenzene (the raw material for styrene manufacture) is manufactured by alkylation of benzene with ethylene (Fig. 2.12). 

Application State-of-the-art technology to produce high-purity ethylbenzene (EB) by liquid-phase alkylation of benzene with ethylene. The Lum-mus/UOP EBOne process uses specially formulated, proprietary zeolite catalyst from UOP. The process can handle a wide range of ethylene feed compositions ranging from chemical (70%) to polymer grade (100%). 

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. 

Techniqttes for the separation of eth benzene in aromatic Cg cuts, particularly super-fractionation and possibly adsorption on molecular sieves, have been covered by spedbe analyses (see Sections 4.Z3 and 4.3.2.1). Thus, only chemical methods need to be examined, especially s>nthesis, which is a decisive hictor at the industrial level, and which involves the alkylation of benzene with ethylene. 

Ethylbenzene is commercially produced almost entirely as an intermediate for the manufacture of styrene. Since only a limited amount can be made by the superfractionation of Ce petroleum aromatics, most ethylbenzene is produced by the alkylation of benzene with ethylene. The alkylation reaction can occur eUher in the vapor phase or the liquid phase. A number of proven processes exist. The liquid phase processes using aluminum chloride catalysts are currently the most widely used. The purpose of this paper is to describe a new and improved version of this latter process which has been commercialized. 

The oldest method of alkylation with ethylene is the liquid phase reaction using anhydrous aluminum chloride as the catalyst. This reaction is a form of the classic Friedel-Crafts reaction and was discovered in 1879 by Balsohn. Most Lewis and Bronsted acids are known to be active for olefin alkylations. Alkylation by H2SO1, and H3PO1, was first shown by Ipatieff, et al, in 1936 who extended the reaction to isoparaffins. For the liquid phase alkylation of benzene with ethylene, however, aluminum chloride is preferred over the other acids, although a co-catalyst or promoter is usually needed to obtain efficient alkylation. AICI3 when dissolved in benzene containing some HCl forms a complex which can be simply described as ... 

The alkylation of arenes with alkenes such as ethylene and propene are of great commercial interest. Ethylbenzene and isopropylbenzene (cumene), products of the Friedel-Crafts alkylation of benzene with ethylene and propene, respectively, are two of the most important petrochemical raw materials. Roberts and Khalaf have follow the developments made in this vast field up to the early part of this decade. This is evident from the large number of references quoted, most of which describe efforts to evaluate conditions for optimal production in the presence of various catalyst systems. 

Camacho et alP have found that during the alkylation of benzene with ethylene in the presence of AICI3 as the catalyst, both alkylation and transalkylation (of the produced ethylbenzene) occur simulta-... 

Styrene is produced by the alkylation of benzene with ethylene followed by catalytic dehydrogenation. It is used in the manufacture of general-purpose and high-impact polystyrene plastics ( 50%), expanded polystyrene ( 7%), copolymer resins with acrylonitrile and butadiene ( 7%) or acrylonitrile only ( 1%), styrene-butadiene latex ( 6%) and synthetic rubber ( 5%), unsaturated polyester resins ( 6%), and as a chemical intermediate. 

Cheng, J.C., et al. A comparison of zeolites MCM-22, beta, and USY for liquid phase alkylation of benzene with ethylene. Sci. Technol. Catal. 1998, 6, 52-60. 

Bhandarkar, M. Lewis, P.J. Dandekar, A.B. Venkat, C.R. Degnan, T.F. EBMax liquid phase alkylation of benzene with ethylene over zeolite MCM-22. In European Petrochemicals Technology Conference London, U.K. Jun 21-22, 1999. 

An important industrial application of CD is the alkylation of benzene with ethylene or propylene to produce ethylbenzene or cumene, respectively, using acidic ion-exchange resins such as Amberlyst or zeolites operating at 130-5065 kPa and 80-500°C. Cumene is a chemical intermediate for the production of phenol, acetone, and alpha-methyl styrene, which are used to produce resins and solvents. Ethylbenzene is an intermediate for styrene, an important monomer for polymers. Alkylation of benzene could also be used to reduce the carcinogenic benzene content of gasoline. 

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