De-oxygenation treatment for noble metal on carbon catalysts used in liquid phase oxidation reactions

摘要

A treatment for de-oxygenating a noble metal on carbon catalyst used in liquid phase oxidation reactions which includes exposing the catalyst to a non-oxidizing environment. The de-oxygenation treatment improves catalyst performance and is particularly suited for noble metal on carbon catalysts used to catalyze the oxidative cleavage of a carboxymethyl substituent from an N-(phosphonomethyl)iminodiacetic acid substrate in an aqueous reaction mixture using an oxygen-containing gas to produce an N-(phosphonomethyl)glycine product. In one embodiment, the catalyst is exposed to a non-oxidizing environment by introducing a non-oxidizing gas and/or reducing gas into a slurry comprising the catalyst in contact with a liquid medium.