Patent ID: 7094939
Filing Date: 2006-08-22
Classification: C07C

Abstract:
1. A process for producing styrene comprising: a) passing ethylene and a first portion of a first recycle stream comprising benzene to an alkylation reactor containing zeolitic alkylation catalyst to alkylate benzene with ethylene and form ethylbenzene and a polyethylbenzene, and withdrawing from the alkylation reactor an alkylation effluent stream comprising benzene, ethylbenzene, and the polyethylbenzene; b) passing at least a portion of the alkylation effluent stream to an alkylation/transalkylation separation section, and withdrawing from the alkylation/transalkylation separation section the first recycle stream comprising benzene, an ethylbenzene stream comprising ethylbenzene, and a polyethylbenzene stream comprising the polyethylbenzene; c) passing a second portion of the first recycle stream and at least a portion of the polyethylbenzene stream to a transalkylation reactor containing a zeolitic transalkylation catalyst to transalkylate benzene with the polyethylbenzene and form ethylbenzene, and withdrawing from the transalkylation reactor a transalkylation effluent stream comprising benzene and ethylbenzene; d) passing at least a portion of the transalkylation effluent stream to the alkylation/transalkylation separation section; e) passing at least a portion of the ethylbenzene stream to a dehydrogenation reactor to dehydrogenate ethylbenzene and form styrene, and withdrawing from the dehydrogenation reactor a dehydrogenation effluent stream comprising styrene and benzene; f) passing at least a portion of the dehydrogenation effluent stream to a dehydrogenation separation section, and withdrawing from the dehydrogenation separation section a second recycle stream comprising benzene; g) extending the run length of the zeolitic alkylation catalyst by passing at least 33% of the second recycle stream to the transalkylation reactor; and h) recovering styrene from the dehydrogenation separation section.