Patent ID: 6872862
Filing Date: 2005-03-29
Classification: C07C

Abstract:
1. A method for forming propylene comprising providing a feedstock containing at least in part a first mixture of hydrocarbons comprising alpha olefins, internal linear olefins, and isoolefins having four carbon atoms per molecule, introducing said feedstock into a combination hydrogenation/double bond isomerization zone wherein (1) any diolefins and acetylenes that may be in said feedstock are converted at least in part to alpha and internal linear olefins, and (2) at least part of said alpha olefins in said feedstock and at least part of said alpha olefins formed by said hydrogenation are converted to additional internal linear olefins thereby producing as a product of said combination zone a second mixture that is enriched in internal linear olefins, passing said second mixture into a distillation zone wherein said second mixture is split into an overhead fraction that is enriched in alpha olefins and isoolefins, and a bottoms fraction that is enriched in internal linear olefins, passing said overhead fraction into a skeletal isomerization zone wherein said isoolefins are converted at least in part to additional internal linear olefins to form a third mixture that is enriched in internal linear olefins, returning said third mixture as co-feed to said distillation zone for the separation of internal linear olefins in said third mixture into said bottoms fraction, passing said bottoms fraction and ethylene into a metathesis zone which favors the disproportionation of internal olefins with ethylene to produce propylene as a product of the process and a separate gasoline grade olefin product, and removing at least one purge stream from at least one of said skeletal isomerization zone and said metathesis zone and employing said at least one purge stream in an alkylation zone to form an alkylate of mixed isooctanes.