| 摘要 |
PURPOSE:To remove tar from crude pyrolignous acid and readily and surely obtain purified pyrolignous acid useful as an industrial raw material, etc., by freezing crude pyrolignous acid and carrying out thawing and collecting of the thawed liquid under respective condition. CONSTITUTION:Crude pyrolignous acid is first completely frozen at <=-1 deg.C, preferably -5 deg.C and the resultant frozen crude pyrolignous acid is then thawed at >=1 deg.C to separate and collect the thawed liquid to 3 deg.C liquid temperature. Thereby the tar is left and removed and the above-mentioned thawing is carried out to <=70-80wt%. crude pyrolignous acid to afford the aimed purified pyrolignous acid.
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