Pore-size regulated zsm-5 zeolite for the synthesis of para-dia lkylbenzenes

Abstract EN

-The dialkylbenzenes can be synthesized by alkylating monoalkylbenzene with an alkylating agent such as an olefin or alcohol over a Friedel-Craft or zeolite catalyst.

On all these catalysts, the dialkylbenzenes mixture produced consists of a thermodynamic equilibrium composition of ortho-, meta-, and para-isomers.

Among the various dialkylbenzenes, the para-isomers such as p-cymene,p-ethyltoluene,p-xylene,p-diethylbenzene are industrially important.

These chemicals are sources for various monomers.

Hence it is of significance to enhance the concentration of the para-isomer in the dialkylbenzenes mixture during alkylation of monoalkylbenzene.

Several techniques have been reported in the literature to modify the diffusion characteristics of the zeolite.

One of the techniques most drawing the attention of researchers is pore size regulation by chemical vapor deposition of tetraethyl orthosilicate.

This modification of the zeolite creates a barrier at the entrance to the zeolite pores, which dramatically enhances the diffusional resistance to the passage of bulkier molecules.

The applications of pore-size regulated zeolite for enhancing para-isomer concentration during ethylation of ethylbenzene and toluene are discussed in this pap