Multistage process for converting oxygenates to hydrocarbons

Claim 1

An integrated continuous process for converting oxygenated organic feedstock to liquid hydrocarbons comprising the steps of (a) contacting feedstock with at least one primary stage dehydration catalyst comprising ZSM-5 type catalyst at elevated temperature and moderate pressure to convert at least a portion of the feedstock to hydrocarbons containing a major fraction of C 2 -C 4 olefins and a minor fraction containing C 5 + heavy hydrocarbons; (b) cooling and separating dehydration effluent from step (a) to provide an aqueous liquid stream, a heavy hydrocarbon liquid stream and a light hydrocarbon vapor stream rich in C 2 -C 4 olefins; (c) pressurizing and heating at least a portion of the olefinic light hydrocarbon stream and substantially all of the heavy hydrocarbon liquid stream to form a secondary stage olefinic feedstream; (d) contacting the olefinic feedstream in a secondary stage with oligomerization catalyst comprising medium-pore shape selective acidic zeolite at substantially increased pressure and moderate temperature to convert olefins to a heavier liquid hydrocarbon effluent stream comprising olefinic gasoline and distillate range liquids; (e) fractionating the liquid hydrocarbon effluent stream from step (d) to obtain a distillate stream, olefinic gasoline stream and lighter hydrocarbon stream; (f) recycling at least a portion of the olefinic gasoline stream to step (d); and (g) hydrogenating olefinic distillate to provide a stabilized distillate product.