METHOD FOR REFINING CRUDE TEREPHTHALIC ACID

摘要

With current methods for manufacturing refined terephthalic acid by means of a hydrogenation reaction of a crude terephthalic acid aqueous solution by means of a precious-metal-supporting activated carbon catalyst, excessive condition settings and extra equipment are used for setting safely in order to ensure quality when setting the hydrogenation reaction conditions based on an increase in production, new equipment or other variations in the amount of production. Disclosed is a method for refining crude terephthalic acid having more economical reaction conditions and stable quality with good reproducibility. With the method for refining crude terephthalic acid, crude terephthalic acid is dissolved in water to form an aqueous solution that is then supplied together with hydrogen gas to the top of an activated carbon catalyst layer. Said aqueous reaction solution is supplied until it rises above the catalyst layer, and by means of a type of reaction vessel that forms/retains a hydrogen-containing gas phase portion above the surface of said aqueous solution, said aqueous solution dissolves (absorbs) hydrogen contained in the upper gas phase portion from the gas-liquid interface, after which the hydrogenation reaction occurs while said solution flows down through the catalyst layer. In addition, the hydrogenation reaction occurs while the hydrogen partial pressure of the gas phase portion at the upper part of the catalyst layer is maintained, based on its relationship with the downward superficial velocity of the respective reaction liquid, in a partial pressure range that is calculated based on the correlation of the hydrogen partial pressure (H2.PP) with the downward superficial velocity (LV), and with the superficial velocity of said aqueous reaction solution that flows down through the catalyst layer introduced as a determining condition.