Patent ID: 7135596

Claim:
A process for making an aromatic carboxylic acid wherein amounts of dissolved iron present in liquid streams are controlled comprising steps comprising: A) Contacting an oxidizable aromatic feed material with molecular oxygen in the presence of an oxidation catalyst having one or more oxidation catalyst metals with an atomic number of about 21 to about 82 and solvent comprising a C 2 to C 5 aliphatic carboxylic acid in a liquid phase reaction mixture in a reactor under oxidation conditions to form a solid a crude aromatic carboxylic acid, a liquid comprising solvent and water, and an off-gas comprising vaporized water and vaporized solvent; B) Separating solid crude aromatic carboxylic acid from the liquid; C) Distilling at least a portion of the off-gas in a distillation column supplied with reflux liquid to separate vaporized solvent from vaporized water such that a liquid stream comprising solvent and a distillation overhead gas comprising vaporized water are formed; D) Returning at least a portion of the liquid stream from step C to the reactor; E) Dissolving at least a portion of the separated solid crude aromatic carboxylic acid in a purification solvent comprising water to form a liquid purification solution; F) Contacting the purification solution with hydrogen in the presence of a Group VIII metal hydrogenation catalyst and under hydrogenation conditions, including temperature of about 450 to about 600° F. and pressure of about 900 to about 1500 psig, effective to form a solution comprising purified aromatic carboxylic acid and liquid comprising purification solvent; G) Separating purified aromatic carboxylic acid from the solution comprising purification solvent which results from step F to form a solid, purified aromatic carboxylic acid and a purification mother liquor; H) Recycling at least a portion of the purification mother liquor to at least one of step C and step E; and I) Adding at least one peroxide of the formula R 1 —O—O—R 2 , wherein R 1 and R 2 are the same or different and are hydrogen or a hydrocarbyl group, to at least one liquid stream resulting from step A or present in or resulting from at least one other step, wherein the peroxide is added in an amount effective to precipitate dissolved iron from the liquid stream.