A process and apparatus for fluidizing a population of catalyst particles having a low catalyst fines content includes a fluidized bed reactor which includes a plurality of catalyst particles in the reactor wherein the catalyst particles having a d2 value of greater than about 40 microns. The catalyst particles are contacted with a fluidizing medium under conditions to fluidize the particles, the reactor includes a continuous reaction zone and separation zone and the fluidized of the catalyst particles are situated within the reaction and both the reaction zone and the separation zone include obstructing members which obstruct the flow of particles such that the catalyst particles can be maintained at an axial gas Peclet number from about 10 to about 20.