Patent ID: 7687671

Claim:
A process for producing light olefins from a methanol-containing feedstock, said process comprising: contacting the methanol-containing feedstock in a methanol conversion reactor fluidized reaction zone with a methanol conversion catalyst and at reaction conditions effective to convert the methanol-containing feedstock to a methanol conversion product stream comprising fuel gas hydrocarbons, light olefins, and C 4+ hydrocarbons; compressing at least a portion of the methanol conversion product stream via a first compressor; treating the compressed methanol conversion product stream in a gas concentration system to recover light olefins and to form a fuel gas hydrocarbon stream and a C 4+ hydrocarbon stream; fractionating the C 4+ hydrocarbon stream to form a process stream comprising C 4+ through C 6− hydrocarbons and a purge stream comprising C 7+ hydrocarbons; contacting the process stream in an olefin cracking reactor with an olefin cracking catalyst and at reaction conditions effective to convert C 4 and C 5 olefins therein contained to a cracked olefins effluent stream comprising light olefins; and separating the cracked olefins effluent stream into a first stream comprising C 1 and C 2 hydrocarbons and a second stream comprising a remainder of the olefin cracking product stream, wherein the first stream is returned to the first compressor for combination with the oxygenate conversion product stream and subsequent treatment in the gas concentration system and the second stream is introduced to the gas concentration system without compression.