Patent ID: 7371915

Claim:
A continuous process for selective conversion of an oxygenate feed containing methanol or a mixture of DME and methanol to propylene comprising the steps of: a) reacting the oxygenate feed and a diluent in an amount corresponding to about 0:5 to 5:1 moles of diluent per mole of oxygenate with dual-function catalyst particles containing a molecular sieve, having the ability to convert at least a portion of the oxygenate to C 3 olefin and to interconvert C 2 and C 4 + olefins to C 3 olefin, in a reaction zone containing at least three moving bed reactors wherein the reaction zone is operated at oxygenate conversion conditions selected to convert oxygenate to propylene and at a catalyst circulation rate through the reaction zone selected to result in a catalyst on-stream cycle time of 200 hours or less to produce an effluent stream containing major amounts of a C 3 olefin product and a water by-product and lesser amounts of a C 2 olefin, C 4 + olefins, C 1 to C 4 + saturated hydrocarbons and minor amounts of unreacted oxygenate, by-product oxygenates and aromatic hydrocarbons and wherein the moving bed reactors are connected in a serial flow configuration with respect to the oxygenate feed and with respect to the stream of catalyst that passes therethrough; b) passing the effluent stream to a separation zone and therein cooling and separating the effluent stream 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 aromatic hydrocarbons; c) recycling at least a portion of the water fraction recovered in step b) to step a) to provide at least a portion of the 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) recycling at least a portion of the C 2 olefin-rich fraction or of the first C 4 + olefin-rich fraction or of a mixture of these fractions to step a); and f) withdrawing coke-containing dual-function catalyst particles from the reaction zone, oxidatively regenerating the withdrawn catalyst particles in a regeneration zone and returning a stream of regenerated catalyst particles to the reaction zone.