Methods of recovering catalyst in solution in the oxidation of cyclohexane to adipic acid

摘要

This invention relates to methods of controlling the oxidation of cyclohexane to adipic acid in the presence of a monobasic acid solvent, by removing the catalyst from the reaction mixture, outside the reaction zone. Substantially all the unreacted cyclohexane along with at least the majority of the monobasic acid solvent are removed. A substantially non-solvent for the catalyst (first constituent), and water are added into the resulting mixture, in such amounts as to maintain one solids-free single liquid phase. This process is highly facilitated in the presence of considerable amounts of adipic acid. The catalyst may then be extracted with water from the solids-free single liquid phase. A water phase containing dissolved catalyst may also be formed by addition of small amounts of a solvent which is substantially non-solvent for the catalyst and substantially non-solvent for the dibasic acids (second constituent), and/or dropping the temperature. Adipic acid may be precipitated after catalyst removal with further addition of second constituent and/or dropping the temperature.