Phthalic anhydride Industrial grade PA CAS85-44-9

At present, there are two kinds of raw material routes of phthalic anhydride in industrial production, namely o-xylene method (referred to as o-xylene method) and naphthalene method.

There are three production processes: fixed bed oxidation, fluidized bed gas phase oxidation and liquid phase oxidation. The production of phthalic anhydride in the world is mainly based on the adjacent fixed bed oxidation technology, which accounts for more than 80% of the total production capacity of phthalic anhydride.

The results show that: 1. The oxidation of o-xylene is mainly carried out by vanadium pentoxide catalyst, and most of the reactors are tubular fixed bed. The filtered dust-free gas is compressed and preheated, mixed with gasified o-xylene vapor, and then enters the reactor for oxidation reaction at 400-460 ℃. The space velocity of feed is 2000-3000h-1, and the concentration of o-xylene in air is 40-60g / m2 (standard). The reaction heat is carried out by molten salt circulating outside the pipe. The reaction product enters the steam generator, and the cooled reaction gas is further cooled to recover the crude phthalic anhydride. The tail gas is washed to recover maleic anhydride and then vented. The crude phthalic anhydride is separated from maleic anhydride, methyl maleic anhydride and benzoic acid with low boiling point by vacuum distillation from crude benzoic anhydride; phthalic anhydride product is obtained by vacuum distillation of tower bottom material. Raw material consumption quota: o-xylene (98%) 1138kg / T.

2. Naphthalene catalytic oxidation method: naphthalene is fused and gasified with air in a fluidized bed or fixed bed reactor with air in the presence of vanadium pentoxide to produce phthalic anhydride gas. The crude anhydride is obtained by condensation and hot melting, and refined phthalic anhydride is obtained by vacuum distillation, condensation and separation after heat treatment. Raw material consumption quota: naphthalene (above 95%) 11250kg / T.