Synthesis, Reactivity, and Cytotoxicity Effect of Pt-Pd-Rh Nanocomposite Cordierite Catalyst during Oxidation of Ammonia Processes

The behavior of the ammonia (NH3) oxidation was studied by selective catalytic oxidation (SCO) over a Pt-Pd-Rh nanocomposite cordierite catalyst in a tubular fixed-bed flow quartz reactor at temperatures between 423 and 623 K. The catalysts' surface properties were characterized using scanning transmission electron microscopy-energy-dispersive X-ray, optical microscopy, and ultraviolet visible. The experimental results show that high activities for NH3 removal were achieved during catalytic oxidation over the Pt-Pd-Rh cordierite catalyst at 623 K with an oxygen content of 4%. N-2 was the main product in the NH3-SCO process over the Pt-Pd-Rh nanocomposite cordierite catalyst. These results also verify the Pt-Pd-Rh metals on cordierite surfaces, resulting in the formation of catalytically active sites at the metal-support interface in the reduction of NH3 in this process. In addition, the Pt-Pd-Rh nanocomposite cordierite-induced cytotoxicity testing was mainly applied to the human lung MRC-5 cell line, and the percentage of cell survival was determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium analysis in vitro. For Pt-Pd-Rh nanocomposite cordierite, only minor cytotoxicity was observed when human lung cells were exposed.