Reactive nitrogen compounds (RNCs) in exhaust of advanced PM–NOx abatement technologies for future diesel applications

摘要: Abstract Long-term exposure to increased levels of reactive nitrogen compounds (RNCs) and particulate matter (PM) affect human health. Many cities are currently not able fulfill European air quality standards for these critical pollutants. Meanwhile, promising new abatement technologies such as diesel particle filters (DPFs) selective catalytic reduction (SCR) catalysts developed reduce PM RNC emissions. Herein, effects a urea-based SCR system on emissions discussed we quantified the highly intermediates isocyanic acid (HNCO) ammonia (NH 3 ), both potential secondary pollutants chemistry. A engine (3.0 L, 100 kW), operated in ISO 8178/4 C1, cycle was used test platform. V 2 O 5 -based catalyst either applied or down-stream high oxidation potential-DPF (hox-DPF). With active SCR, nitric oxide (NO) dioxide (NO ) conversion efficiencies 0.86–0.94 0.86–0.99 were obtained. On other hand, mean HNCO and NH 240–280 1800–1900 mg h −1 . molar basis, accounted 0.8–1.4% NH 14–25% emitted RNCs. roads, systems will partly be inactive when exhaust temperatures drop below 220 °C. The only during 75% cycle, urea dosing stopped restarted several times. Consequently, NO but interestingly, still converted. Such light-off shutdown events frequent urban driving, compromising overall deNO x efficiency. Another important effect technology is illustrated by /NO ratio, which >1 with indicating that basic rather than acidic after the SCR catalyst. Under conditions, stable. widespread use various converter technologies already affected release. Diesel (DOCs) hox-DPFs increased NO  emissions, three-way (TWCs) those investigated substantially lowered emissions, while comparable TWC vehicles (300–1500 mg h ). If future, combined DPF/SCR change ambient levels, compositions atmospheric redox- acid/base-chemistry traffic-affected areas.