| abstract |
A process for co-producing para-xylene and styrene from a feed ( 1 ) of hydrocarbons containing xylenes and ethylbenzene is described, the process comprising the following succession of steps: n a step for separating the feed in a simulated moving bed in an adsorption column ( 6 ) containing beds of an adsorbent, from which an extract that is rich in para-xylene ( 7 a ) of at least 99.7% purity and at least one raffinate ( 7 b ) containing ethylbenzene, ortho-xylene, meta-xylene and a very small quantity of para-xylene is withdrawn; a step for dehydrogenating ( 10 ) the ethylbenzene contained in the raffinate ( 7 b ) to styrene; at least one step for primary separation of the stream ( 11 ) from the dehydrogenation step ( 10 ), to eliminate by-products; a step for separating the purified mixture ( 18 ) derived from the stream ( 11 ) containing styrene, unconverted ethylbenzene, meta-xylene and ortho-xylene, from which a stream ( 21 a ) that is rich in styrene of at least 99.8% purity and a stream ( 21 b ) containing unconverted ethylbenzene, meta-xylene and ortho-xylene is withdrawn; and a step for isomerising the stream ( 21 b ), the effluent being recycled to the adsorption column ( 6 ). |