The Maleic Anhydride Plant, originally designed in 1979 used benzene as a base for producing maleic anhydride. In June 2006, due to environmental and economic reasons, the Maleic Anhydride Plant was re-designed to use n-butane as a base. The declared capacity in the first year was 9,600 tons of crude maleic anhydride.

Maleic anhydride is produced by catalytic oxidation of n-butane in a reactor. The produced gas mixture contains maleic anhydride in a gaseous state. In the next phase, the gas mixture is cooled to about 60°C to separate the liquid crude AMK. The remaining maleic anhydride in the gas mixture is washed in the washing column, forming maleic acid. Maleic acid is dehydrated to form crude maleic anhydride. The total amount of crude maleic anhydride is distilled to remove residual impurities.

The produced liquid maleic anhydride is stored at a temperature above 60°C, or further processed in the pastillation section to produce solid maleic anhydride.