Cordierite-supported Pt–Pd–Rh ternary composite for selective catalytic oxidation of ammonia

This study elucidates ammonia (NH3) oxidation by selective catalytic oxidation (SCO) over a Pt–Pd–Rh ternary composite cordierite substrate catalyst in a tubular fixed-bed flow quartz reactor (TFBR) at temperatures of 423–623 K. A Pt–Pd–Rh ternary composite cordierite substrate catalyst was prepared by incipient wetness impregnation with aqueous solutions of H2PtCl6, Pd(NO3)3 and Rh(NO3)3 that were coated on cordierite ceramic honeycomb substances. Experimental data indicate that high NH3 reduction activity was achieved during catalytic oxidation over the Pt–Pd–Rh cordierite substrate catalyst at 623 K with an oxygen content of 4%. Notably, N2 was the predominant product of the NH3–SCO process over the Pt–Pd–Rh cordierite substrate catalyst. These experimental results also confirm that an initial high concentration of NH3 influent decreases ammonia removal efficiency. Further, catalysts were characterized by SEM, TGA–DTA, FTIR and TEM. Analytical results indicate that catalytic behavior is associated with the Pt–Pd–Rh ternary composite and cordierite ceramic honeycomb substrate.

Graphical abstractThis figure using TEM provides important information about the surface structure of the (a) fresh and (b) aged Pt–Pd–Rh ternary composite cordierite substrate catalyst. The observations of agglomerates by TEM indicate that the composite catalyst particles form a fine cotton-like species. These results confirm that the dispersion phenomena of the catalyst increase the efficiency of removal of NH3.Figure optionsDownload full-size imageDownload as PowerPoint slide