An improved methanol-to-olefin (MTO) product recovery scheme is provided
which enables substantial reduction in the amount of light olefins that
are undesirably captured in a dimethylether (DME) recycle stream and
improved recovery of methanol when a portion of the methanolic feed to
the MTO reaction zone is used as the scrubbing solvent in a primary DME
absorption zone in order to recycle this DME oxygenate by-product to the
MTO reaction zone. In accordance with the present invention, a liquid
solvent stream recovered from the primary DME absorption zone is
subjected in a stripping zone to light olefin stripping conditions
sufficient to lift a substantial portion of the light olefins that are
absorbed in the DME solvent without stripping a significant portion of
this methanol solvent, thereby increasing the recovery of desired light
olefins while simultaneously diminishing the amount of light olefins
carried by the DME recycle stream back to MTO conversion step.