Separation of diethylbenzene isomers on silicalite in the presence of

Abstract

A process for separating p-diethylbenzene from a diethylbenzene isomers mixture by selective adsorption of p-diethylbenzene on a silicalite adsorbent is disclosed in the present invention, wherein a compressed high pressure CO.sub.2 or propane is used as a carrier for carrying a fixed amount of the diethylbenzene isomers mixture to the silicalite adsorbent bed for the selective adsorption, a first stage effluent stream containing a rich meta-diethylbenzene (m-DEB) and/or ortho-diethylbenzene (o-DEB), but having substantially no para-diethylbenzene (p-DEB) is eluted from the adsorbent bed; when p-DEB of the mixture starts to appear in the first stage effluent stream, a much higher pressurized CO.sub.2 or propane used as a desorbent is then fed into the adsorbent bed, and a second stage effluent stream conaining a rich p-DEB, but having substantially no other DEB isomers is thereby eluted from the adsorbent bed. The diethylbenzene isomers procucts contained in the first and second effluent streams, respectively, can be easily separated from CO.sub.2 or propane simply by reducing the pressure thereof, wherein the resulting CO.sub.2 or propane can be re-compressed and recycled.