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

Received: May 31, 2006
Revised: May 31, 2006
Accepted: May 31, 2006
Download Citation: RIS|BibTeX|https://doi.org/10.4209/aaqr.2006.06.0004  

Cite this article:
Hung, C.M (2006). Selective Catalytic Oxidation of Ammonia to Nitrogen on CuO-CeO2 Bimetallic Oxide Catalysts. Aerosol Air Qual. Res. 6: 150-169. https://doi.org/10.4209/aaqr.2006.06.0004

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 CuOCeO₂ 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-CeO2₂ 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.

Keywords: Catalytic Selective Oxidation (SCO); Tubular Fixed-bed Reactor (TFBR); Ammonia; Coprecipitation; CuO-CeO<sub>2</sub> Bimetallic Oxide Catalyst