Investigation of NO and NO

This research investigates a hybrid methodology for the abatement of low-temperature NOx by amalgamating non-thermal plasma (NTP) with a Cu/Al2O3 catalyst under conditions that simulate diesel exhaust. A catalyst consisting of 2 wt% Cu-loaded γ-Al2O3 was synthesized through the technique of incipient wetness impregnation and subsequently characterized using X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS), thereby confirming the presence of metallic Cu0 and its uniform distribution. Plasma experiments were executed at input power levels of 20, 30, and 40 W. The results indicated that NTP in isolation effectively facilitated the oxidation of NO to NO2, attributable to the generation of reactive species including O3 and O*. Nevertheless, when this plasma treatment was employed in conjunction with the catalyst, both NO and NO2 were concurrently eliminated via the rapid selective catalytic reduction (SCR) mechanism, resulting in substantially enhanced NOx conversion rates. Further examination revealed that a reduction in the electrode gap resulted in an increase in electric field strength (E = V/d), which in turn amplified plasma reactivity. At a gap of 3 cm, the most significant NOx reduction efficiency was attained due to improved NO oxidation and an optimal NO/NO2 ratio entering the catalyst. In summary, this study elucidates that the efficacy of plasma-catalytic systems is influenced not solely by plasma power but also by the geometrical configuration of the reactor. These findings offer essential insights for the design of energy-efficient systems aimed at low-temperature NOx control.