Phthalic anhydride (PA) production via gas-phase o-xylene oxidation demands an extraordinarily precise thermal envelope. The catalytic reactor—packed with V₂O₅/TiO₂ catalyst—operates at 280–380 °C and releases substantial exothermic heat that must be removed uniformly to prevent hot-spot formation, catalyst deactivation, and selectivity loss. Switch condensers cycling between 130–170 °C solidify PA vapors from the reactor exit, while melt tanks and crude-PA storage vessels must stay above the 130.8 °C melting point. The downstream rectification column—operating near atmospheric pressure with 23+ separation stages—requires stable reboiler temperatures up to ~295 °C to deliver the high-purity PA demanded by plasticizer and resin markets.

Chemie's four-fluid portfolio addresses every thermal node in this chain. Phthalic Anhydride Eurotherm 330 (−49 ~ 315 °C, viscosity 4.04 mm²/s at 40 °C, pour point −68 °C) provides supercooling and precise switch-condenser cycling. Phthalic Anhydride Eurotherm 320 (−30 ~ 320 °C, viscosity 9.8 mm²/s at 40 °C) handles melt-tank and pre-rectification heating with minimal system pressure. Phthalic Anhydride Eurotherm THT (up to 350 °C, superior oxidation resistance) maintains the extreme-duty reactor and reboiler circuits. Phthalic Anhydride Eurotherm 1000 (high heat capacity, robust film stability) supports large-volume closed-loop systems, minimizing top-up frequency and extending fluid service life across the entire plant.

All four fluids operate well below steam-system pressures, eliminating high-pressure vessel licensing costs, reducing leak risk, and enabling safe, continuous throughput—critical advantages in handling a flammable, corrosive anhydride environment.