ABSTRACT
Production of maleic anhydride has grown rapidly since its commercialization in the US in the early 1930s. Although butenes can be oxidized to maleic anhydride, their higher cost over benzene, together with the greater capital cost of the plant, has limited their utilization. The reactor exit gases are cooled to 55–65°C. About 60% of the maleic anhydride is condensed as a liquid and removed from the vapour stream. Purification of the crude maleic anhydride is carried out by vacuum distillation or sublimation. Maleic anhydride is either sold in the molten state or formed into pellets and flakes and bagged. Alusuisse Italia has developed a fluid-bed catalytic process which uses an organic solvent for maleic anhydride recovery. The most important outlet, accounting for over 50% of maleic anhydride consumption, is for the manufacture of unsaturated polyester resins. Maleic anhydride is toxic and an irritant to skin and mucous membranes leading to burning and ulceration.
