| abstract |
The present invention relates to a process for the production of propylene in which in a first step isobutanol is subjected to a simultaneous dehydration and skeletal isomerisation to make substantially corresponding olefins, having the same number of carbons and consisting essentially of a mixture of n-butenes and iso-butene and in a second step n-butenes are subjected to methathesis, said process comprising:n a) introducing in a reactor a stream (A) comprising isobutanol, optionally water, optionally an inert component, b) contacting said stream with a catalyst in said reactor at conditions effective to dehydrate and skeletal isomerase at least a portion of the isobutanol to make a mixture of n-butenes and iso-butene, c) recovering from said reactor a stream (B), removing water, the inert component if any and unconverted isobutanol if any to get a mixture of n-butenes and iso-butene, d) fractionating said mixture to produce a n-butenes stream (N) and to remove the essential part of isobutene optionally recycled with stream (A) to the dehydration/isomerization reactor of step b), e) sending the stream (N) to a methathesis reactor and contacting stream (N) with a catalyst in said methathesis reactor, optionally in the presence of ethylene, at conditions effective to produce propylene, f) recovering from said methathesis reactor a stream (P) comprising essentially propylene, unreacted n-butenes, heavies, optionally unreacted ethylene, g) fractionating stream (P) to recover propylene and optionally recycling unreacted n-butenes and unreacted ethylene to the methathesis reactor. |