Method and system for regenerating catalyst from a plurality of hydrocarbon conversion apparatuses

A method for forming olefins in a methanol to olefin reactor system, comprising:

• contacting in a plurality of risers at a gas superficial velocity of greater than about 8 m/s of a first reaction unit a first oxygenate with a first catalyst under conditions effective to convert at least a portion of the first oxygenate to first light olefins and at least partially deactivating the first catalyst to form a deactivated first catalyst, the first reaction unit comprising a shell having a first end comprising a catalyst retention zone and each riser associated with the first reaction unit comprising a first end and a second end, the plurality of risers being in the shell and a catalyst return line being positioned therebetween the risers, the at least partially deactivated first catalyst exiting the second end into the catalyst retention zone and then flowing through the single catalyst return line back to the first ends of the risers;
• contacting in a plurality of risers at a gas superficial velocity of greater than about 8 m/s of a second reaction unit a second oxygenate with a second catalyst under conditions effective to convert at least a portion of the second oxygenate to second light olefins and at least partially deactivating the second catalyst to form a deactivated second catalyst, the second reaction unit comprising a shell having a first end comprising a catalyst retention zone and each riser associated with the second reaction unit comprising a first end and a second end, the plurality of risers being in the shell and a catalyst return line being positioned therebetween the risers, the at least partially deactivated second catalyst exiting the second end into the catalyst retention zone, and then flowing through the single catalyst return line back to the first ends of the risers;
• wherein the first and second reaction units are operated under similar reactor conditions to produce substantially identical products;
• directing from above the catalyst retention zone a portion of the deactivated first catalyst and a portion of the deactivated second catalyst to a common regeneration unit at a rate from about 0.3 to about 3 times the total feed rate of first and second oxygenates, and for each reactor, the rate of withdrawing the portion of the catalyst for regeneration is from about 0.5% to about 5% of the catalyst;
• regenerating the deactivated first catalyst and the deactivated second catalyst to form regenerated catalysts, wherein the first and second oxygenate comprise methanol and the first and second catalysts are each silicoaluminophosphate molecular sieve catalysts;
• directing a first portion of the regenerated catalysts to the first reaction unit at an inlet above the catalyst retention zones and within the same region of a separation zone in the reaction unit as associated with the second end of the riser reactors thus increasing the life and selectivity of the catalysts to ethylene and/or propylene;
• and
• directing a second portion of the regenerated catalysts to the second reaction unit;
• wherein the catalyst retention zones are below the risers or riser regions where the light olefins and other products enter the separation zone.