Patent ID: 7989669
Filing Date: 2011-08-02
Classification: C07C,Y02P

Abstract:
1. A process for producing one or more olefins from an oxygenate feed, comprising: providing an oxygenate stream; adding a recycle stream with a controlled amount of propane and dimethyl ether to the oxygenate stream to form a feed stream in order to maintain a relatively high selectivity for light olefins, wherein the recycle stream contains from 50 wt % to 99 wt % dimethyl ether, based on total weight of the recycle stream, and wherein the recycle stream contains from 0.5 wt % to 50 wt % propane, based on total weight of the recycle stream; contacting the feed stream with an oxygenate-to-olefin catalyst in a reactor to form an olefin stream that contains dimethyl ether, at least one olefin, and propane, wherein the propane in the olefin stream is in excess of that in the feed stream; separating at least a majority of the propane and dimethyl ether from the olefin stream to form a propane/DME-containing stream; and separating propane from the propane/DME-containing stream in an amount that is at least as much as the amount produced in the reactor during the reaction process, thus forming the recycle stream.