Patent ID: 7642390

Claim:
In a method of manufacturing styrene by dehydrogenation of ethylbenzene in the presence of steam at elevated temperatures in a reactor system containing a dehydrogenation catalyst, the improvement comprising the steps of: (a) separating the unreacted ethylbenzene from the crude styrene by fractionation in an ethylbenzene-styrene fractionator carried out at an overhead pressure below about 200 mmHg in the presence of a polymerization inhibitor; (b) condensing the ethylbenzene overhead vapor from the fractionator in an azeotropic vaporizer to provide heat for boiling a reactor feed consisting essentially of an azeotropic mixture of ethylbenzene and water; and, (c) compressing the vaporized reactor feed, the overhead vapor from the fractionator, or both to obtain an azeotropic mixture of ethylbenzene and water at a suitable pressure for feeding to the reactor system.