| 摘要 |
PURPOSE:To prepare high-purity tar acid having a very low content of impurities, esp. carboxylic acid and tar base, by removing carboxylic acids from crude tar acid and then bringing the tar acid into contact with a cationic ion exchange resin. CONSTITUTION:Crude tar acid separated from liquefied coal, condensate from coal gasification, etc. is mixed with carbonic acid-based alkaline aqueous soln. (e.g. aqueous soln. of sodium carbonate in the concn. of about 5-30%). The mixt. is left at rest and carbonic acid-based alkaline water phase which has dissolved carboxylic acids, is removed. Then the crude tar acid (having a water content of 1wt% or higher) is brought into contact with a cation exchange resin (e.g. styrene/divinylbenzene copolymer resin with a sulfonic acid group) for removal of the base, followed by distillation to obtain refined tar acid. A greater portion of sulfur compds. can be removed when the crude tar acid is brought into contact with an oxidant prior to distillation.
|
