Effect of Water Vapor and Nitrogen Oxides on Electricity Pulse-Sparked Catalysis for Soot Combustion
The rapid combustion of soot at low temperatures is critical for diesel engine cold-start emission control. This study investigates the effects of water vapor (H2O) and nitrogen oxides (NOx) on electricity-pulse-sparked catalysis (EPSC) for soot combustion over a ceramic filter paper-based potassium-supported antimony-doped tin oxide (K/ATO/CP) monolithic catalyst. Under EPSC with 2000 J pulses, the presence of H2O and NOx adversely affected soot combustion performance, yet average reaction rates remained high at 12.0 μmol·gcat−1·s−1 and 9.53 μmol·gcat−1·s−1, respectively, exceeding conventional thermal catalysis (<8 μmol·gcat−1·s−1). In situ Raman and concentration profiles revealed that electricity pulses promote rapid H2O desorption, effectively alleviating H2O poisoning and restoring catalyst activity. In contrast, NOx adsorption forms stable nitrates (e.g., KNO3) that desorb slower than the soot combustion process, leading to incomplete recovery of activity. These findings highlight the importance of adsorbate desorption kinetics in EPSC and suggest that using weakly basic alkaline-earth metals (e.g., Mg, Ca, Sr) with lower nitrate decomposition temperatures could mitigate NOx poisoning. The results provide guidance for advancing EPSC technology in hybrid vehicle exhaust aftertreatment systems.