Apparatus for the continuous liquid-phase catalytic oxidation of alkyl-substituted aromatic compounds

In an apparatus for oxidizing an alkyl-substituted aromatic compound in the liquid phase with a molecular oxygen-containing gas in a lower aliphatic carboxylic acid solvent in the presence of an oxidation catalyst, said apparatus comprising a reaction vessel, a gas exhaust port at the top of the vessel, an inlet at the bottom of the vessel for feeding said molecular oxygen-containing gas, an inlet for feeding said solvent, an inlet for feeding said catalyst, an inlet for feeding said alkyl-substituted aromatic compound, an outlet for withdrawing the oxidation reaction product, and an agitator within the vessel, said agitator consisting of a rotating shaft provided along the axial direction of the vessel and a plurality of stages of agitating blades secured to said rotating shaft at spaced intervals;

• the improvement wherein at least one stage of the agitating blades consists of comb-like flat blades each of which is composed of a plurality of comb-like pieces aligned at spaced intervals;
• wherein the total area of said plurality of comb tooth-like pieces is about 0.83 to about 3 times the total area of the spaces among said comb tooth-like pieces in each comb-like flat blade when taken on a flat plane.