Patent ID: 7414167

Claim:
A continuous process for selective conversion of an oxygenate feed to propylene comprising the steps of: a) reacting the oxygenate feed and a first diluent in an amount corresponding to about 0.1:1 to 12:1 moles of diluent per mole of oxygenate with particles of a first dual-function catalyst, having the ability to convert oxygenates to C 3 olefin and to interconvert C 2 and C 4 + olefins to C 3 olefin, in a first reaction zone containing at least three moving bed reactors wherein the reaction zone is operated at oxygenate conversion conditions selected to convert the oxygenate to propylene and to produce a first effluent stream containing major amounts of a C 3 olefin product and a water by-product; lesser amounts of a C 2 olefin, C 4 + olefins, C 1 to C 4 + saturated hydrocarbons and aromatic hydrocarbons; and minor amounts of unreacted oxygenate, by-product oxygenates and highly unsaturated hydrocarbons; b) cooling and separating at least a portion of the first effluent stream in a separating zone into a vaporous fraction rich in C 3 olefin, a water fraction containing unreacted oxygenate and by-product oxygenates and a liquid hydrocarbon fraction containing heavier olefins, heavier saturated hydrocarbons and minor amounts of highly unsaturated hydrocarbons and aromatic hydrocarbons; c) passing at least a portion of the water fraction recovered in step b) to step a) to provide at least a portion of the first diluent used therein; d) separating the vaporous fraction into a C 2 olefin-rich fraction, a C 3 olefin-rich product fraction and a first C 4 + olefin-rich fraction; e) charging at least a portion of the olefins contained in the C 2 olefin-rich fraction to step a); f) contacting at least a portion of the C 4 + olefins contained in the first C 4 + olefin-rich fraction with particles of a second dual-function catalyst, having the ability to interconvert C 4 + olefins to C 3 olefin, in a second reaction zone containing at least one moving bed reactor wherein the second reaction zone is operated at heavy olefin interconversion conditions including an inlet temperature at least 15° C. higher than the maximum temperature used in the first reaction zone effective to convert a substantial portion of the C 4 + olefin to propylene and to produce a second effluent stream containing major amounts of propylene; g) passing at least a portion of the second effluent stream to step b); h) withdrawing coke-containing particles of the first dual-function catalyst from the first reaction zone, oxidatively regenerating the withdrawn catalyst particles in a first regeneration zone and passing at least a portion of the regenerated catalyst particles back to the first reaction zone; and i) withdrawing coke-containing particles of the second dual-function zeolitic catalyst from the second reaction zone, oxidatively regenerating the withdrawn catalyst particles in a second regeneration zone and returning at least a portion of the regenerated catalyst particles back to the second reaction zone.