Patent EA-002261-B1 (EA)
Title: A process for conversion of oxygenates to produce light olefins
Inventor: MILLER LAWRENCE W
IPC: C07C1/20
Filed: 2000-08-18
Abstract: 1. A process for the conversion of a feedstream comprising an oxygenate to produce light olefins, said process comprising: a) passing said feedstream in the presence of a diluent to a dense phase zone in a lower reaction zone of a fast-fluidized bed reactor containing a fluidized non-zeolitic catalyst, and at least partially converting said feedstream to a product stream comprising light olefins and deactivating at least a portion of said catalyst to produce a spent catalyst having a carbonaceous deposit thereon; b) passing said product stream, an unconverted portion of the feedstream, and a catalyst mixture comprising spent catalyst and a regenerated catalyst to a transition phase zone located in said lower reaction zone above said dense phase zone wherein the unconverted portion of the feedstream is essentially completely converted to produce a transition zone effluent comprising light olefins and the catalyst mixture; c) passing the transition zone effluent to a first separation zone in an upper disengaging zone of said reaction zone to separate a first portion of the catalyst mixture and to provide a first separated product stream and collecting the first portion of the catalyst mixture in an upper catalyst bed in the upper disengaging zone; d) passing the first separated product stream to a second separation zone to provide a net product stream comprising a reduced amount of catalyst relative to the first catalyst stream and returning a second portion of the catalyst mixture to the upper catalyst bed; e) returning at least a portion of the catalyst mixture from the upper catalyst bed to the dense phase zone; and f) withdrawing a third portion of the catalyst mixture from the upper catalyst bed, at least partially regenerating the third portion of the catalyst mixture to provide a regenerated catalyst, and returning the regenerated catalyst to the lower reaction zone at a point above the dense phase zone. 2. The process of claim 1 wherein the light olefins comprise olefins having 2 to 4 carbon atoms per molecule the oxygenate is selected from the group consisting of methanol, ethanol, propanol, dimethyl ether, and mixtures thereof. 3. The process of claims 1 or 2 wherein the non-zeolitic catalyst comprises a silicoaluminophosphate catalyst. 4. The process of claims 1 or 2 wherein the dense phase zone comprises a bed height of about 2 meters to about 4 meters. 5. The process of claims 1 or 2 further comprising cooling the catalyst mixture of step (e) prior to returning the catalyst mixture to the dense phase zone. 6. The process of claims 1 or 2 wherein the effective conditions for converting the feedstock in the dense phase include a superficial velocity of less than 2 meters per second and the transition phase includes a superficial velocity of greater than or equal to 2 meters per second. 7. The process of claim 1-5 wherein the second separation stage comprises a cyclone separation stage and said cyclone separation stage comprises about one to about three cyclone separation stages. 8. The process of claims 1 or 5 wherein at least one catalyst recirculation standpipe is provided to return a portion of the catalyst mixture from the upper catalyst bed to the dense phase zone. 9. The process of claim 1 or 2 wherein a partition extends about an intermediate portion of the reaction vessel to segregate the reaction zone from the disengaging zone. 10. The process of claim 8 wherein a riser extends vertically within the reaction vessel from the reaction zone into a central section of the disengaging zone, for conducting the product stream and catalyst mixture and defines a discharge opening within said disengaging zone for discharging the product stream and catalyst mixture with, a tangential velocity into the disengaging zone.