Oxidation of benzaldehyde to benzoic acid using O2fine bubbles

Abstract

A new swirling liquid flow type fine bubble organic reactor was developed to introduce gaseous reactants as fine bubbles for gas-liquid organic reactions. Promotion of gas-liquid organic reaction by O2fine bubbles was verified using oxidation of benzaldehyde as a model reaction. The remarkable promotion effects of O2fine bubbles were confirmed. Promotion of the reaction was dominated by improvement of the conversion rather than the selectivity. Reaction using O2fine bubbles required about 1/5 of the reaction time for 90 % conversion compared to the aeration method with the same O2flow rate. The unique properties of fine bubbles compared to normal- sized bubbles, such as large surface area per volume, low floating speed, and maintenance of supersaturation of gas in the solvent, were considered to have greatly affected the conversion rate improvement.