METHODS OF REPLACING WATER AND CYCLOHEXANONE WITH ACETIC ACID IN AQUEOUS SOLUTIONS OF CATALYST

This invention relates to methods of replacing water and cyclohexanone with acetic acid in an aqueous solution of catalyst, preferably a cobalt compound. Such an aqueous solution is produced by extracting catalyst with water from a cyclohexanone/water solution of reaction products made by the direct oxidation of cyclohexane to adipic acid. The replacement of both water and cyclohexanone are conducted in a solvent exchange column, wherein acetic acid dissolves the catalyst, while water vapors force the cyclohexanone into a condenser, followed by a decanter wherein two liquid phases may be formed and separated; an upper liquid phase containing a majority of cyclohexanone and a lower liquid phase containing a majority of water. The cyclohexanone may be removed in a pretreatment zone, wherein also part of the water may be removed, before the concentrated catalyst extract enters the solvent exchange column.