Novel K-Doped Mn–Ce–O Wet Oxidation Catalysts with Enhanced Stability

The catalytic wet oxidation of aqueous phenol over Mn–Ce–O mixed oxide catalysts was shown to be accompanied by undesirable formation of heavy polymers on the catalyst surface, leading to severe loss in catalytic activity and in mineralization selectivity. New potassium-doped Mn–Ce–O mixed oxide catalysts were developed and benchmarked for the destruction of concentrated phenolic (103 ppm) synthetic wastewater at very mild conditions (110°C and 0.5 MPa O2 pressure). Remarkable improvements in mineralization selectivity were attained. Complete removal of total organic pollution was achieved within 10–20 min and mineralization selectivity exceeding 95% was attained over fresh K–Mn–Ce–O catalyst. The leach-proof ability of the catalyst was confirmed from analysis of the treated waters. Detailed characterization of fresh and spent K-doped catalysts revealed drastic reduction in carbonaceous deposits on the catalyst surface, even after successive runs of non-regenerated catalyst samples. The catalyst surface was found to be active after the catalyst was reused thrice, though this time the TPO-detected surface carbonaceous species were far less than those in the nonpromoted Mn–Ce–O catalyst.