GB899314A - Separation of aromatic isomers - Google Patents

Abstract

At least partial resolution of mixtures of aromatic isomers which are (a) trisubstituted benzenes; (b) substituted naphthalenes or (c) anthracene and phenanthrene is effected by selective adsorption on a zeolitic crystalline, partially dehydrated, metallo alumino silicate having pores of 7-13 diameter. The adsorbent is zeolite X, a molecular sieve described in Specification 777,233 and U.S.A. Specification 2,882,244; adsorbed material may be desorbed by a displacement fluid readily separated from the adsorbed material and which may be hydrocarbon, halohydrocarbon, amine, ether, sulphide or heterocyclic, many being specified. Vapour phase separation is preferred at 0 DEG -800 DEG F. and 0-1,000 p.s.i.g., the adsorbent being alternately used in separation and desorbed, the desorbent being recovered and recycled. Highly polar compounds such as ethers, thioethers, water, alcohol, mercaptans, and heterocyclic nitrogen or oxygen compounds should be removed from the feed, e.g. by contact with a 13 molecular sieve. The adsorbent may become deactivated and is reactivated by contact with hot flue gas or air. The separations of alkyl and halogen substituted compounds are referred to and the following separations are exemplified:- (1) trimethylbenzenes; (2) methylnaphthalenes; (4) dimethylnaphthalenes; (7) anthracene and phenanthrene; and (9) chloronaphthalenes.ALSO:At least partial resolution of mixtures of aromatic isomers which are (a) trisubstituted benzenes; (b) substituted naphthalenes or (c) anthracene and phenanthrene is effected be selective adsorption on a zeolitic crystalline partially dehydrated, metallo alumino silicate having pores of 7-13 diameter. The adsorbent is a molecular sieve of the X-crystalline form such as are described in Specification 777,233 and U.S.A. Specification 2,882,244 and adsorbed material may be desorbed by a displacement fluid readily separated from the adsorbed material and which may be hydrocarbon, halohydrocarbon, amine, ether, sulphide or heterocyclic, many being specified. Vapour phase separation is preferred at 0 DEG F.-800 DEG F. and 0-1,000 p.s.i.g., the adsorbent being alternately used in separation and desorbed, the desorbent being recovered and recycled. Highly polar compounds such as ethers, thioethers, water, alcohol, mercaptans, and heterocyclic nitrogen or oxygen compounds should be removed from the feed, e.g. by contact with a 13 molecular sieve. The adsorbent may become deactivated and is reactivated by contact with hot flue gas or air. The separations of alkyl and halogen substituted compounds are referred to and the following separations are exemplified (1) trimethylbenzenes; (2) methylnaphthalenes; (4) dimethylnaphthalenes; (7) anthracene and phenanthrene; and (9) chloronaphthalenes.