Summary Chemical engineering

Maleic anhydride (MA) is classified as a commodity chemical with global production in excess of 1.5 million tons per year [1, 9]. It is primarily used in the manufacture of polyester resins for commercial applications in construction, marine, automotive, textiles, and consumer products applications. It is also widely used as a chemical precursor in the agricultural and chemicals industries, as well as in the food, consumer goods, and personal care products industries. MA was first produced industrially in the 1930s by vapor-phase catalytic oxidation of benzene over a vana- dium oxide and molybdenum oxide catalyst. Due to the ease of oxidation and high selectivity for MA, the benzene process dominated global production until the early 1980s. Rapidly increasing costs and growing environmental concerns associated with benzene use motivated a transition to an alternate feedstock. Fur- thermore, benzene conversion is inherently inefficient due to the conversion of a C6 feedstock to a C4 product (lower atom economy). This resulted in the exploration of C4 feedstocks, and a process to produce MA from low-cost n-butane. Monsanto built the first butane to MA plant in 1974 and by the mid-1980s, 100% of U.S. production was from butane. Despite having lower selectivity, the butane process was preferred due to the lower feedstock cost, decreased environmental impact, and increased atom economy. The increased atom economy results in a competitive mass yield for butane with the lower selectivity. Advancements in catalysts for the butane reaction increased activity to enable conversion of benzene-based plants without capacity loss. Further advancements led to more energy efficient, solvent-based isolation and purification methods [9].