Enhancing S.I. Engine Performance with Metal-Doped Zeolite X Derived from Rice Husk

The increasing prevalence of harmful NOx emissions from gasoline engines necessitates the development of alternatives to traditional three-way catalytic converters. This study investigates the potential of low-cost zeolites derived from rice husk ash as a promising alternative. Na-X zeolites derived from rice husk ash were characterized using X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM) to determine their structural properties and morphology. These zeolites were then modified with copper (Cu) and iron (Fe) ions to create Cu-X and Fe-X zeolite catalysts. The catalysts were wash coated onto cordierite honeycomb monoliths and integrated and properly housed in a steel casing catalytic converter and fitted near the exhaust manifold of a twin-cylinder nano engine. Engine performance and emissions were evaluated under various operating loads (4, 7, 10, 13, and 16 kW). NOx, CO, HC, CO2, and O2 emissions were measured using an AVL DI gas analyzer. The results demonstrated that the developed Cu-X and Fe-X zeolite converters significantly outperformed the conventional catalytic converter in reducing NOx emissions, while maintaining comparable performance for other pollutants. The enhanced NOx reduction capabilities of the zeolite catalysts can be attributed to their unique structural properties and the synergistic effect of the copper and iron ions.