Patent ID: 6852879

Claim:
A process for the manufacture of an aromatic carboxylic acid comprising steps comprising (a) oxidizing in a reaction zone a feed material comprising an aromatic compound in a liquid phase reaction mixture comprising the aromatic compound, water, a monocarboxylic acid solvent, an oxidation catalyst and a source of molecular oxygen to form a product comprising an aromatic carboxylic acid and a gas phase comprising water vapor, unreacted molecular oxygen and gaseous monocarboxylic acid solvent; (b) removing all or part of the gas phase from the reaction zone to a separation device comprising at least one internal titanium component; and (c) separating the gas phase in the separation device into a liquid phase comprising monocarboxylic acid solvent and a second gas phase comprising water vapor; characterized in that the separation device is treated to control accumulation of solid iron oxide deposits on a surface of an internal titanium component by a process comprising discontinuing at least steps (b) and (c) and contacting, in the substantial absence of molecular oxygen in the separation device, a surface of the titanium component with an aqueous solvent composition comprising an organic acid which is at least one alkyl monocarboxylic acid of 2 to 6 carbon atoms, benzoic acid or a mixture thereof and a hydrohalide acid in amounts effective to dissolve solid iron oxide deposits without substantially dissolving titanium metal from the titanium component.