Maleic anhydride production

Patent Pending Maleic anhydride was traditionally produced by the oxidation of benzene or other aromatic compounds. As of 2006, only a few smaller plants continue to use benzene. Instead, most maleic anhydride is produced by vapor-phase oxidation of n-butane. The overall process converts the methyl groups to carboxylate and dehydrogenates the backbone. The selectivity of the process reflects the robustness of maleic anhydride, with its conjugated double-bond system. In both cases, benzene and butane are fed into a stream of hot air, and the mixture is passed through a catalyst bed at high temperature. The ratio of air to hydrocarbon is controlled to prevent the mixture from igniting. Vanadium pentoxide and molybdenum trioxide are the catalysts used for the benzene route, whereas vanadyl phosphate is used for the butane route.