Transition metal-containing catalysts and their use as oxidation catalysts

摘要

The invention relates to a process for oxidizing N-(phosphonomethyl)iminodiacetic acid or a salt thereof, comprising contacting N-(phosphonomethyl)iminodiacetic acid or a salt thereof with an oxidant in the presence of a transition metal containing catalyst.The catalyst comprises a carbon support having formed thereon a transition metal composition comprising a transition metal (M) and nitrogen. The catalyst carbon support has a Langmuir surface area of from about 500 m<Sup>2</Sup>/g to about 2100 m<Sup>2</Sup>/g,the transition metal constitutes between 1.6% and 5% by weight of the catalyst. The catalyst is further characterized such that, when the catalyst is analyzed by X-Ray Photoelectron Spectroscopy (XPS) (i) the N 1s spectra includes a component having a binding energy of from about 398.4 eV to about 398.8 eV, and (ii) the Co 2p spectra includes a component having a binding energy of from about 778.4 eV to about 778.8 eV; or as generating ions corresponding to the formula MN<Sub>x</Sub>C<Sub>y</Sub><Sup>+</Sup> when the catalyst is analyzed by Time-of-Flight Secondary Ion Mass Spectrometry (ToF SIMS) as described in Protocol A; the weighted molar average value of x being from about 0.5 to about 8 and the weighted molar average value of y being from about 0.5 to about 8.