HIGH PRESSURE AND HIGH CAPACITY OXYGENATE CONVERSION WITH CATALYST EXPOSURE CYCLE

摘要

A gas-solids reaction system is provided for improving product recovery in a multiple reactor reaction system. An oxygenate feedstock, desirably of high concentration in oxygenate, is reacted with a catalyst having a low to modest acidity and a Si/Al₂ ratio of from 0.10 to 0.32. The reaction occurs in a reaction zone of a fluidized bed reactor at an oxygenate partial pressure of at least 45 psia and a reactor gas superficial velocity of at least 10 ft/s, conveying catalyst through the reaction zone to a circulation zone. The catalyst undergoes displacement with an inert gas in the circulation zone at a displacement gas superficial velocity of at least 0.03 m/s, after which at least a portion, preferably a large portion is returned to the reaction zone. The catalyst has a residence time in the circulation zone of at least twice that of the residence time of catalyst in the reaction zone. Extraordinary catalyst activity at high olefin selectivity results despite insignificant changes in coke on catalyst and coke yield when compared to lower pressure operations.