| 摘要 |
Terephthalic acid is continuously produced by introducing into an oxidn. zone, a mixt. of a solvent, consisting of acetic acid contg. 1-7% water, and p-xylene contg. a catalyst with a ratio of solvent to p-xylene being maintained at from 4:1 to 7:1 by wt.; an oxygen contg. gas is passed into the oxidn. zone which is maintained at 160-180 degrees C and the residence time of the mixt. in the oxidn. zone is from 30-120 mins. The catalyst is a mixt. of a Co cpd., a Mn cpd. and a bromide, the Co being 1200-2500 ppm. of the solvent, the Mn being 1-30% of the Co, and the bromide is at least 1.5 times the weight of Co+Mn. In a further process as above, the gaseous prod. is passed to a waiting zone for at least 30 mins. at a temp. ranging from 50 degrees C below to 25 degrees C above the reaction zone, then the mixt. is passed to a sepn. zone where the solid terephthalic acid is sepd. The prod. is used to make polyethyleneterephthalate. Previously the product from p-xylene oxidation has required expensive purification to obtain sufficiently high quality for polyester mfr. The above gives high quality terephthalic acid without excessive combustion of acetic acid and the prod. only require a simple treatment to enable it to be satisfactory for polyester mfr. |
