Catalyst development for the selective oxidation of ethoxylates to their corresponding ether carboxylic acids

The aerobic selective oxidation of polyethoxylates to their corresponding carboxylic acids was investigated using supported Au-based catalysts in aqueous alkaline solution. Introduction of Pt as secondary metal to the titania supported Au catalyst led to a significant boost in activity while maintaining total selectivity. A screening of different preparation methods and metal ratios led to a titania supported AuPt catalyst with a substantially reduced intermediate leaching of the catalytically active metals. A long-term stability study showed no noble metal loss of this particular catalyst after a set of repeated batches, but still revealed a distinct loss in activity due sintering of the metal nanoparticles. By switching from titania to ceria as support material, intermediate metal leaching could be prevented completely while maintaining total selectivity and further enhancing the activity.