The reaction of partial oxidation of n-butane to maleic anhydride, catalyzed by VPO, was experimentally studied in a fluidized bed reactor, operated alternating oxidizing and reducing feeds, simulating in this way a circulating fluidized reactor. The influence of feed composition and oxidation/reduction time on butane conversion, maleic anhydride selectivity and maleic anhydride production per unit catalyst weight and time was studied. Results for the simulated circulating fluidized bed were compared with that of a conventional fluidized bed. (C) 2009 Elsevier B.V. All rights reserved.