Recirculating solids reactor for butane oxidation: Reaction engineering aspects

The gas phase oxidation of butane was studied in a fixed bed to obtain an improved kinetic model to support Du Font's recirculating solids reactor technology. The experiments were done in an integral reactor, containing 0.5 g of unsupported V/P/O catalyst. Feed composition, temperature, and space time were varied independently over a wide range. Six sets of rate expressions were considered based upon a parallel/consecutive reaction network. Best results were obtained with a modified Sharma model and an adsorption model. Both models describe adequately the experimentally found inhibition by water and maleic anhydride. Selectivity loss to CO and CO₂ occurs primarily via the parallel reaction, though at very high butane conversion the loss resulting from maleic anhydride degradation also becomes important.