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Catalytic Applications of Zeolites in Industrial Processes
Published in Subhash Bhatia, Zeolite Catalysis: Principles and Applications, 2020
Diethylbenzene (DEB) can be obtained by alkylation of ethylbenzene with ethylene over ZSM-5 catalyst. A 2:1 meta:para ratio of diethylbenzene is produced with only 4% ortho isomer. Table 19 gives the distribution of para, ortho, and meta diethylbenzenes by alkylation reactions. 99% p-diethylbenzene is produced when ZSM-5 catalyst is modified to induce para selectivity.
Chemicals from Aromatic Hydrocarbons
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
Diethylbenzene derivatives are produced as side-products of the alkylation of benzene with ethylene. Since there is only a limited market for diethylbenzene, much of it is recycled by transalkylation give ethylbenzene.
Alkyl transfer reactions on solid acids. The disproportionation of ethylbenzene and toluene on H-mordenite and HY zeolites
Published in Petroleum Science and Technology, 2018
After a sufficiently long time on stream, the rate of this acid catalyzed reaction is virtually constant and can be correlated to the number of strong BrØnsted acid sites. It was also found that the higher the rate of ethylbenzene disproportionation the shorter the induction period. They also suggested that the rate of ethylbenzene disproportionation seemed to be a suitable parameter for characterizing the acidity of monofunctional catalysts. Karge et al.(1983) have also shown that under appropriate conditions, acidic zeolites catalyze disproportionation reaction of ethylbenzene in a completely selective manner; Others authors reported on the diethylbenzene deficit during the early stages of the reaction and later on steady states were reached and they observed a 1:1 relation (benzene:diethylbenzene) in the product stream. An induction period, was observed (Cardoso et al. 1998) and conversion increased with time on stream until a maximum was reached, a yield of benzene was sufficiently higher than that of diethylbenzene during the induction period, although under these reaction conditions since no dealkylation occurred they should be equal from reaction stoichiometry (1:1). A change during the induction period in the distribution of the diethylbenzene isomers, with no shape selectivity being observed. The reaction of ethylbenzene takes place in a completely selective manner, yielding benzene and diethylbenzene as the only products. During the same reaction with medium pore zeolites the same authors (Camiloti et al. 1997) observed no induction period, a net deactivation of the catalyst and shape selectivity effects on the diethylbenzene isomers. Pradhan et al. (1999) observed benzene as the major product in an 80% of ethylbenzene conversion on HZSM-5, attributed this to the dealkylation reactions (due to smaller pores) and this was supported by minor products being toluene, xylene and diethylbenzene. Similar results were observed by Rhodes and Rudham (1993) while studying the disproportion of ethylbenzene on zeolite-Y without the production of toluene and xylene.