This invention relates to the use of a supplemental
promoter in conjunction with a noble-
metal-containing catalyst comprising a carbon support in catalyzing
liquid phase oxidation reactions, a process for making of an improved catalyst comprising such a supplemental
promoter, and an improved catalyst comprising such a supplemental
promoter. In a particularly preferred embodiment, a supplemental promoter (most preferably
bismuth or
tellurium) is used in conjunction with a noble-
metal-containing catalyst comprising a carbon support in a
liquid phase oxidation process wherein N-(phosphonomethyl)
iminodiacetic acid (i.e., “PMIDA”) or a salt thereof is oxidized to form N-(phosphonomethyl)
glycine (i.e., “
glyphosate”) or a salt thereof. The benefits of such a process include increased oxidation of the
formaldehyde and
formic acid by-products, and, consequently, decreased final concentrations of those by-products as well as other undesirable by-products, most notably N-methyl-N-(phosphonomethyl)
glycine (i.e., “NMG”).