Used 25,000 TPY Phthalic Anhydride plant built by Balcke-Durr GmbH of Germany to use orthoxylene as raw material to produce phthalic anhydride flakes of purity up to 99.9%. The plant includes the process sections of oxidation, condensation, distillation, flaking and packing. The process uses BASF O4-66 catalyst which allows 100 g of orthoxylene / Nm3 air load.