Process for continuously separating phthalic anhydride from the reaction gases of the catalytic oxidation of o-xylene and/or naphthalene
AssigneeDavy International Aktiengesellschaft
InventorsGerhard Keunecke, Anton Klopfer, Lothar Sterck
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Abstract
Phthalic anhydride is continuously separated from the reaction gas mixture formed by the catalytic oxidation of o-xylene and/or naphthalene, by treating said rection gas mixture in at least two absorption stages with organic absorbents. The absorbent employed in the first absorption stage is a mixture of phthalic anhydride and benzoic acid. The absorbent employed in the subsequent absorption stage(s) contains maleic anhydride and may also contain phthalic anhydride.
Claims15
In the process for the continuous separation of phthalic anhydride from the reaction gas of the catalytic oxidation of o-xylene and/or naphthalene whereby said reaction gas is treated with organic absorbents in an absorption zone, the absorbents, which are enriched with phthalic anhydride, are withdrawn from the absorption zone, absorbents are generated by separation of the phthalic anhydride therefrom and are returned to the absorption zone, the improvement which comprises treating the reaction gas in a first absorption stage with a liquid mixture comprising benzoic acid and phthalic anhydride, and in at least one additional absorption stage with a liquid, maleic anhydride-based absorbent containing from 0 to about 85% by weight phthalic anhydride.
Dependencies are inferred from the claim text.