Selective Catalytic Oxidation of Ammonia to Nitrogen on CuO-CeO2 Bimetallic Oxide Catalysts

Abstract

This study addresses the performance of the selective catalytic oxidation (SCO) of ammonia to N2 over a CuO-CeO2 bimetallic oxide catalyst in a tubular fixed-bed reactor (TFBR) at temperatures from 423 to 673 K in the presence of oxygen. CuO-CeO2 bimetallic oxide catalyst was prepared by co-precipitation with Cu(NO3)2 and Ce(NO3)3 at various molar concentrations. This study tested operational stability and investigated how the influent NH3 concentration (C0 = 500-1000 ppm) influences the capacity to remove NH3. The catalysts were characterized using XRD, FTIR, PSA, SEM and EDX. Ammonia was removed by oxidation in the absence of CuO- CeO2 bimetallic oxide catalyst, and the formation of copper (II) and cerium (IV) oxide active sites was confirmed. Additionally, the effects of the NH3 content of the carrier gas on the catalyst’s reaction rate (r) were observed. The results revealed that the extent of catalytic oxidation of ammonia in the presence of a CuO-CeO2 bimetallic oxide catalyst was a function of the molar ratio Cu:Ce in the bimetallic catalyst. The kinetics of catalyzed NH3 oxidation are described using the rate expression of the Eley-Rideal kinetic model. Also, experimental results indicate a reasonable mechanism for the catalytic oxidation of ammonia.