GB1257025A - - Google Patents

Abstract

1,257,025. Separating aromatic hydrocarbon mixtures. BRITISH PETROLEUM CO. Ltd. 24 Jan., 1969 [6 Feb., 1968], No. 5796/68. Addition to 1,104,314. Heading C5E. One or more components of a hydrocarbon mixture comprising C 8 and/or C 9 , alkyl and/or alkenyl, aromatic hydrocarbons are separated by contact in the vapour phase with a PNT- type compound having the basic nuclear structure and which forms an inclusion complex more readily with one or more components of the mixture than with the other components, and desorbing in the vapour phase the more readily absorbed component(s) by displacement with an eluent comprising one or more hydrocarbons also capable of forming an inclusion complex with the PNT-type compound, the desorption thereby occurring without distortion of the crystal lattice of said compound. The process preferably operates continuously with repeated absorption and desorption cycles. Suitable PNT compounds are tris-(o-phenylenedioxy) cyclotriphosphazene, tris - (o - phenylenediamino) cyclotriphosphazene and tris-(2,3-naphthyldioxy) cyclotriphosphazene. Such compounds may be used in the free state, or admixed with a thermosetting resin binder, or on an inert support. The eluent may be paraffinic, olefinic, aromatic or alicyclic, but is preferably an aromatic of lower carbon number than the absorbed component(s), e.g. benzene, toluene or a xylene. Examples describe the separation of a mixture of ortho- and para-xylenes, the eluent being toluene.