Different stages of development of Dupont's new circulating fluidized-bed (CFB) technology for maleic anhydride from its conception to commercialization are summarized. The discussion covers(a) Background on why use a CFB reactor over alternatives for partial oxidation of n-butane to maleic anhydride, (b) Feasibility demonstration of the concept in a laboratory-scale CFB reactor, (c) Development of an improved attrition resistant vanadium phosphorous oxide catalyst, (d) Steady-state performance demonstration in a 10x scaled-up pilot plant, (e) Catalyst life study, (f) Scale-up to a large demonstration plant and (g) Commercialization of the technology.