How is maleic anhydride produced?
Generally by vapour phase oxidation of butane.
The reaction is:
Air is mixed with superheated butane and fed into the reactor which contains vanadium-phosphorus oxide catalyst supported on silica. The process is performed at 400 - 430 degrees C. The reaction gases are cooled and maleic anhydride is condensed off. Further maleic anhydride is recovered from the maleic acid in the water scrubber by dehydration. The crude anhydride is then purified by distillation under reduced pressure.