Patent ID: 6586621
Filing Date: 2003-07-01
Classification: B01J,C07F

Abstract:
A process for the preparation of N-(phosphonomethyl) glycine or a salt thereof, the process comprising:oxidizing N-(phosphonomethyl) iminodiacetic acid in an aqueous reaction medium in the presence of an oxidation catalyst comprising a noble metal on a carbon support, thereby producing an aqueous reaction mixture comprising N-(phosphonomethyl) glycine, formic acid or formaldehyde; separating oxidation catalyst from said reaction mixture to produce a filtrate comprising N-(phosphonomethyl) glycine, formic acid or formaldehyde; evaporating water, formic acid or formaldehyde from said filtrate to produce an overhead vapor stream; condensing water, formic acid or formaldehyde from said overhead vapor stream and forming an aqueous treatment mixture containing water, formic acid or formaldehyde; contacting said aqueous treatment mixture with an oxidizing agent in the presence of a noble metal catalyst on a carbon support and a promoter metal comprising a metal effective to promote oxidation of formic acid or formaldehyde, thereby forming a treated condensate by oxidizing formic acid or formaldehyde contained in said treatment mixture; and recycling treated condensate incorporating it into an aqueous medium for N-(phosphonomethyl) iminodiacetic acid in the further oxidation thereof to N-(phosphonomethyl) glycine or a salt thereof.