Multistage process for converting oxygenates to liquid hydrocarbons with ethene recycle

A continuous multi-stage catalytic system for converting oxygenated feedstock to liquid hydrocarbons comprising

• primary stage catalytic reactor means containing acidic zeolite catalyst for converting oxygenate to olefinic hydrocarbons rich in C.sub.2 -C.sub.4 alkenes;
• interstage separation means for recovering water and light hydrocarbon vapor from the primary stage effluent stream;
• including means for pressurizing the primary stage hydrocarbon liquid stream rich in C.sub.3.sup.+ components and an ethene-rich vapor stream;
• secondary stage catalytic oligomerization reactor means containing medium pore shape selective acidic zeolite oligomerization catalyst for converting C.sub.3.sup.+ olefinic hydrocarbons to heavier liquid hydrocarbons;
• fractionation means for separating secondary stage effluent into a light hydrocarbon stream containing C.sub.2 -C.sub.4 aliphatic hydrocarbons, a C.sub.5.sup.+ gasoline stream and distillate range stream;
• means for recovering and recycling at least a portion of the ethene to the primary stage for combining with oxygenated feedstock.

A process for converting feedstock consisting essentially of methanol, dimethyl ether or mixtures thereof to liquid hydrocarbons comprising the steps of

• contacting the feedstock with zeolite catalyst in a primary catalyst stage at elevated temperature and moderate pressure to convert feedstock to hydrocarbons comprising C.sub.2 -C.sub.4 olefins and C.sub.5.sup.+ hydrocarbons;
• cooling and separating effluent from the primary stage to recover a liquid hydrocarbon stream and a light hydrocarbon vapor stream rich in C.sub.2 -C.sub.4 olefins;
• compressing the olefinic light hydrocarbon stream to condense a liquid olefinic hydrocarbon stream rich in C.sub.3.sup.+ olefins and recovering an ethene-rich gaseous stream;
• further pressurizing and contacting the condensed liquid olefinic hydrocarbon stream in a secondary catalytic stage with oligomerization catalyst comprising medium-pore shape selective acidic zeolite at substantially increased pressure and moderate temperature to convert at least a portion of olefins to a heavier liquid hydrocarbon product stream comprising olefinic gasoline and distillate range liquids;
• and
• recovering ethene in a gaseous stream for recycle to the primary catalytic stage.