Use of a supplementary catalyst in combination with a catalyst containing noble metal supported in carbon in oxidation reactions in liquid phase.

A process for manufacturing an oxidation catalyst system, the process comprising mixing a catalyst containing a noble metal with a supplemental promoter in the presence of N- (phosphonomethyl) iminodiacetic acid or a salt thereof and formic acid or formaldehyde, in that the catalyst containing a noble metal comprises a noble metal and a carbon support; and the mass ratio of the promoter supplemental to the catalyst containing the noble metal is at least 1: 15,000.