Gas−Liquid−Liquid Three-Phase Reactive Extraction for the Hydrogen Peroxide Preparation by Anthraquinone Process

The gas−liquid−liquid three-phase reactive extraction at elevated pressures for the preparation of hydrogen peroxide by anthraquinone route was investigated experimentally. The integrated process of the oxidation reaction of anthrahydroquinone in the working solution by oxygen from the oxygen-containing gas and the extraction of hydrogen peroxide from the working solution with deionized water were carried out in a sieve plate column of 50 mm in diameter at 0.1−0.6 MPa and 323 K. All operating conditions focused in this work such as operating pressure, superficial gaseous velocity, and oxygen concentration in the initial gas were the advantageous parameters for enhancing the conversion of anthrahydroquinone in the integrated process, because the rate-controlling step of the oxidation reaction of anthrahydroquinone is the mass transfer of oxygen at the interface between the gaseous phase and the organic phase. The agitating effect caused by the gaseous phase made the droplets of the organic phase become smaller and, thus, increased the liquid−liquid interfacial contact areas, resulting in the improvement of the mass transfer of hydrogen peroxide at the water−working solution interface. However, a large excess of the gas superficial velocity caused the decrease in the extraction efficiency of hydrogen peroxide. The real gas superficial velocity on the upper section of the extraction column at the high initial concentration of oxygen was lower than that at the low oxygen concentration, resulting in the decrease of the extraction efficiency of hydrogen peroxide. There was no change in the extraction efficiency of hydrogen peroxide with increasing operating pressure, although the mass transfer rate of hydrogen peroxide at the water−working solution interface increased slightly.