Patent ID: 6977318

Claim:
A method for forming propylene comprising providing a feed containing at least in part t-butyl alcohol, subjecting said feed to dehydration conditions which favor the conversion of said t-butyl alcohol to isobutylene to form a first stream that contains isobutylene at least in part, subjecting said first stream to skeletal isomerization conditions wherein at least part of said isobutylene is converted to a mixture of butene-1 and butene-2 to form a second stream that contains at least in part isobutylene, butene-1 and butene-2, subjecting said second stream to disproportionation with an ethylene feed under conditions that favor the metathesis of at least part of said butene-2 present in said second stream with said ethylene feed to form propylene and a gasoline by-product, recycling a stream from said metathesis step to said isomerization step, said recycle stream containing at least in part isobutylene and butene-1 so that in said skeletal isomerization step at least part of said recycled isobutylene is converted to additional butene-1 and butene-2 and at least part of said recycled butene-1 is converted to a mixture of butene- 1 and butene-2, and recovering from said metathesis step a propylene stream as a product of the process and a separate gasoline stream as a by-product of the process.