Catalytic Performance and Characterization of Copper-based Rare Earth Composite Materials for Selective Catalytic Oxidation Reaction with Simulated Synthetic Ammonia Stream

摘要

Renewable energy and fuels typically contain nitrogen compounds, which convert to ammonia (NH3) during gasification. Hence, copper-based rare earth composite metal materials were tested for their activity in the selective catalytic oxidation (SCO) of NH3 with O2 in simulated biomass gasification stream. This study addresses the oxidation behavior of NH3 at temperatures between 423 and 723 K by SCO over a Cu-La-Ce composite catalyst that was prepared by coprecipitating copper nitrate, lanthanum nitrate and cerium nitrate at a molar ratio of 6:2:2 and a calcination temperature of 773 K. The catalysts were characterized using cyclic voltammetry (CV), UV-Vis absorption spectra, dynamic light-scattering (DLS), zeta potential, excitationemission fluorescent matrix (EEFM) spectroscopy, X-ray powder diffraction (XRD) and environmental scanning electron microscopy with an energy dispersive X-ray spectrometer (ESEM-EDX). In this report, approximately 98% of the NH3 was decreased by catalytic oxidation over the Cu-La-Ce composite catalyst. The synergetic interaction between the three metal components played an important role in the elevated activity of the NH3 catalytic oxidation. In addition, N2 was the primary product of this NH3-SCO process. The CV reversible redox ability may explain the significant activity of the catalysts. The UV-Vis absorption spectra observations indicate that the Cu~(2+)-O~(2-) species with a peak absorbance value at 230 nm accounted for the higher catalytic performance. The X-ray powder diffraction approach confirmed that copper (II), lanthanum (III) and cerium (IV) oxide active sites were formed on the Cu-La-Ce composite catalyst.