Purification of carboxylic acids by catalytic hydrogenation

The present invention relates to a process for the production of an aromatic carboxylic acid comprising: a) introducing a crude aromatic carboxylic acid solution into a purification reactor vessel, wherein the purification reactor vessel is operating under pressure, b) introducing hydrogen gas into the purification reactor vessel, c) dissolving the hydrogen gas in the crude aromatic polycarboxylic acid solution as the solution flows down a wall of a vertical conduit onto a distributor, wherein the purification reactor vessel has a gas-liquid contact area to plant throughput (capacity) ratio of at least 0.55 m2/ te/h of carboxylic acid for dissolving the hydrogen gas in the crude aromatic polycarboxylic acid solution to produce a reaction solution, and d) contacting the reaction solution with a supported catalyst bed to produce a purified aromatic carboxylic acid,; wherein the supported catalyst bed is submerged in the reaction solution and a liquid level of the reaction solution is maintained above the suppor