Selective oxidation of NH3 to N-2 over Cu catalysts supported on MFI-type metallosilicate

Copper catalysts supported on MFI-type metallosilicate were prepared and th eir activities for selective oxidation of NH3 were examined. Among the cata lysts tested in this study, copper catalysts supported on MFI-type metallos ilicate showed the highest activity. This catalyst selectively converted NH 3 to N-2 at 250-400 degreesC in the presence of excess oxygen. The characterization of acidity and the effect of copper content revealed t hat active site of the catalyst in selective oxidation of NH3 was the coppe r supported on the strong acidic site of metallosilicate. From NH3-TPD, NH3 -O-2 pulse reaction and FT-IR measurements, amino groups formed on the cata lyst surface were found to be intermediates of the NH3 selective oxidation. The following mechanism for,the selective oxidation of NH3 was suggested; NH3 is first adsorbed on the Bronsted acid site of metallosilicate and then converted to NH4+. Secondly, dinitrogen group intermediate is formed by th e oxidative dehydration of NH4+. Finally, dinitrogen group intermediate is dehydrated oxidatively to N-2.