Title: Method for preparing terephthalic acid
Application Number: 95118792 Application Date: 1995.11.16
Publication Number: 1130173 Publication Date: 1996.09.04
Approval Pub. Date: 2000.12.13 Granted Pub. Date: 2000.12.13
International Classifi-cation: C07C51/43;C07C63/26
Applicant(s) Name: Mitsubishi Chemical Co., Ltd. Address:
Inventor(s) Name: Izumisawa Yoshiaki;Kawahara Tsukasa;Toyosawa Akihi
Attorney & Agent: ZHANG MINGYU
Abstract:
    A process for producing terephthalic acid, which comprises dissolving crude terephthalic acid in an aqueous medium, contacting it with a platinum group metal catalyst for purification under a temperature condition of from 260 DEG to 320 DEG C., crystallizing terephthalic acid from the aqueous solution of terephthalic acid by cooling the aqueous solution stepwise in a plurality of crystallizers connected in series, in such a manner that in a first crystallization zone, the crystallization temperature is adjusted to a level within a range of from 240 DEG to 260 DEG C. and agitating is carried out by impeller with a power requirement of impeller within a range of from 0.4 to 10 kw/m3, and then, in a second crystallization zone, the crystallization temperature is adjusted to a level within a range of from 180 DEG to 230 DEG C., which is lower by from 20 DEG to 60 DEG C. than the crystallization temperature in the first crystallization zone, followed by solid-liquid separation, and drying the separated terephthalic acid crystals to obtain terephthalic acid particles wherein the proportion of particles having particle sizes exceeding 210 mu m is at most 10 wt %. Absorbent articles, especially catamenials, having improved fluid directionally, comfort and fit.
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