Preparation and Performance Analysis of γ-Al2O3 Supported Cu-Ru Bimetallic Catalysts for the Selective Wet Air Oxidation of Aqueous Ammonia to Nitrogen

Series of Copper Ruthenium (Cu-Ru) bimetallic catalysts supported on γ-Al2O3 with different metal loading are prepared and investigated for catalytic wet air oxidation of ammonia to nitrogen. The ammonia decomposition activity was studied at three different temperatures i.e. 150oC, 200oC, and 230 oC and it is found that catalytic activity increases with the increase in temperature along with the high selectivity towards nitrogen production. The results also revealed that the bimetallic Cu-Ru/ γ-Al2O3 are much more efficient especially stable than the corresponding monometallic Cu and Ru catalysts. Up to 99 % ammonia decomposed to N2 without any undesirable nitrites and nitrates at 230 oC by optimizing catalysts to ammonia ratio. So, it can be considered as a potential method to remove a large amount of ammonia from wastewater. Furthermore, the catalysts characterization results strongly suggested that there is a strong relationship between catalytic activity and Ru and Cu contents in bimetallic catalysts. The presences of both metals (Cu and Ru) affect the reactivity and coverage of oxygen species, as well as protecting each other from leaching. The combination of all effects including the strong interaction between metals, synergistic effect, proper oxygen coverage and resistance against leaching could be attributed to the enhancement of the catalytic activity of Cu-Ru/ γ-Al2O3 catalyst.