Method for obtaining high-purity methanoic acid from hydrous methanoic acid through separation and refining

The present invention is a reduced-pressure distillation or reduced pressure distillation was added with (normally) the combination of the intermediate pressure rectifier, the preparation of high purity acid method. The present invention was added and vacuum distillation method (constant) pressure rectifier in series to separate the water and formic acid, formic acid and the effective separation of the water, and formic acid concentration in the feed for the three kinds of different design process for the preparation of carboxylic acid . Acid yield of 99.0% -99.99%, and the acid product purity of 99.9% -100%.