What Are the Preparation Methods of Maleic Anhydride?

I. Oxidation of Benzene to Maleic Anhydride

After heating to a tubular catalytic reactor, benzene is mixed with air through a heat exchanger. The oxidation reaction is carried out under reaction conditions of 0.1-0.2 MPa pressure and 350-400°C temperature. The resulting product passes through two heat exchangers and a cooler and is cooled to near the dew point (55-65°C). The cooled reactants enter the separator, where crude maleic anhydride is obtained at the bottom of the separator and enters the crude maleic anhydride tank.

The top effluent of the separator is sent to the scrubber column and washed with water. The air top and unreacted benzene can be recovered by adsorption. The aqueous solution at the bottom of the scrubber tower is fed to the stripper where the water is separated and the resulting maleic anhydride is fed to the crude maleic anhydride tank. The crude maleic anhydride is further fed to the distillation column for distillation and refining to obtain maleic anhydride. The resulting maleic anhydride can be isomerized to obtain fumaric acid and malic acid.

II. Partial Oxidation of C4 to Maleic Anhydride

For the industrial production of maleic anhydride, the non-separated C4 fraction or the C4 fraction after the separation of isobutylene and butadiene is used as raw material. the C4 fraction is mixed with air and then fed into a human fluidized bed oxidation reactor and contacted with the catalyst in the reactor at a temperature of 300-500°C to produce maleic anhydride. The reaction product at the top of the oxidation reactor enters the absorption tower, water is used as the absorbent and the top gas passes through the waste water.

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