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    • 5. 发明授权
    • Process for preparing terephthalic acid of high quality
    • 制备高品质对苯二甲酸的方法
    • US4877900A
    • 1989-10-31
    • US177951
    • 1988-04-05
    • Akio TamaruYoshiaki Izumisawa
    • Akio TamaruYoshiaki Izumisawa
    • C07C63/26C07B61/00C07C51/265C07C51/487
    • C07C51/265
    • The present invention provides a process of preparing terephthalic acid of high quality which is characterized by:oxidizing p-xylene with molecular oxygen in an acetic acid solvent in the presence of a catalyst comprised of at least one heavy metal and bromine at a temperature of from 180.degree. to 230.degree. C. to convert at least 95 wt % of the p-xylene into terephthalic acid and, optionally, subjecting the resultant reaction mixture to low temperature post-oxidation with molecular oxygen at temperatures lower than the temperature of the first oxidation reaction, thereby obtaining a slurry containing terephthalic acid particles whose spectral reflectance defined below is not less than 70% and whose reflectance ratio (400/500) defined below is not less than 0.92;subjecting the slurry to high temperature post-oxidation with molecular oxygen at a temperature of from 235.degree. to 290.degree. C. and then to crystallization; andcollecting the resultant terephthalic acid from the reaction mixture.Spectral reflectance=a spectral reflectance at 500 nm determined according to a white light illumination method.Reflectance ratio (400/500)=(spectral reflectance at 400 nm)/(spectral reflectance at 500 nm).
    • 本发明提供了一种高品质对苯二甲酸的制备方法,其特征在于:在由至少一种重金属和溴组成的催化剂存在下,在乙酸溶剂中,在分子氧下, 将至少95重量%的对二甲苯转化成对苯二甲酸,并且任选地使得到的反应混合物在低于第一次氧化温度的温度下用分子氧进行低温氧化 反应,得到含有下述光谱反射率为70%以上且其反射率(400/500)以下所定义的对苯二甲酸粒子的浆料为0.92以上的浆液。 在235〜290℃的温度下用分子氧对浆料进行高温后氧化,然后结晶; 并从反应混合物中收集所得对苯二甲酸。 光谱反射率=根据白光照明方法确定的500nm处的光谱反射率。 反射率(400/500)=(400nm处的光谱反射率)/(500nm处的光谱反射率)。