A two-zone fluidized bed reactor for catalytic propane dehydrogenation

A new reactor technology is employed for propane dehydrogenation over a Cr₂O₃/Al₂O₃ catalyst. This reactor allows the continuous regeneration of the catalyst, but avoids the transfer of large amounts of solid between two reactors, since one single vessel is employed. The experimental work was carried out in a bench scale reactor using two configurations: (a) a two-zone fluidized bed reactor (TZFBR), where propane and oxygen are fed at different levels, providing separated zones for the reaction and catalyst regeneration; (b) an internal circulating fluidized bed reactor (ICFBR), where the addition of an axial dividing slab allows the partition of the vessel, giving two beds connected at the top and bottom and enabling better catalyst circulation. The effects of the main operating variables were studied: bed temperature, gas velocity, oxygen flow rate fed to the reactor, relative length between the oxidizing and reacting zones and the W/F ratio. Under suitable conditions, steady-state operation with propene yields as high as 30% can be achieved, with small requirements of oxygen to continuously regenerate the catalyst.