Back to Search
Start Over
Effects of a combined Diesel particle filter-DeNOx system (DPN) on reactive nitrogen compounds emissions: a parameter study
- Source :
- Environmental sciencetechnology. 46(24)
- Publication Year :
- 2012
-
Abstract
- The impact of a combined diesel particle filter-deNO(x) system (DPN) on emissions of reactive nitrogen compounds (RNCs) was studied varying the urea feed factor (α), temperature, and residence time, which are key parameters of the deNO(x) process. The DPN consisted of a platinum-coated cordierite filter and a vanadia-based deNO(x) catalyst supporting selective catalytic reduction (SCR) chemistry. Ammonia (NH₃) is produced in situ from thermolysis of urea and hydrolysis of isocyanic acid (HNCO). HNCO and NH₃ are both toxic and highly reactive intermediates. The deNO(x) system was only part-time active in the ISO8178/4 C1cycle. Urea injection was stopped and restarted twice. Mean NO and NO₂ conversion efficiencies were 80%, 95%, 97% and 43%, 87%, 99%, respectively, for α = 0.8, 1.0, and 1.2. HNCO emissions increased from 0.028 g/h engine-out to 0.18, 0.25, and 0.26 g/h at α = 0.8, 1.0, and 1.2, whereas NH₃ emissions increased from0.045 to 0.12, 1.82, and 12.8 g/h with maxima at highest temperatures and shortest residence times. Most HNCO is released at intermediate residence times (0.2-0.3 s) and temperatures (300-400 °C). Total RNC efficiencies are highest at α = 1.0, when comparable amounts of reduced and oxidized compounds are released. The DPN represents the most advanced system studied so far under the VERT protocol achieving high conversion efficiencies for particles, NO, NO₂, CO, and hydrocarbons. However, we observed a trade-off between deNO(x) efficiency and secondary emissions. Therefore, it is important to adopt such DPN technology to specific application conditions to take advantage of reduced NO(x) and particle emissions while avoiding NH₃ and HNCO slip.
- Subjects :
- Time Factors
Reactive nitrogen
Inorganic chemistry
Environment
Residence time (fluid dynamics)
Nitric Oxide
Catalysis
Diesel fuel
chemistry.chemical_compound
Environmental Chemistry
Urea
Nitrites
Vehicle Emissions
Nitrates
Temperature
General Chemistry
Reactive Nitrogen Species
chemistry
Torque
Environmental chemistry
Particle
Particulate Matter
Particle filter
Filtration
Gasoline
Subjects
Details
- ISSN :
- 15205851
- Volume :
- 46
- Issue :
- 24
- Database :
- OpenAIRE
- Journal :
- Environmental sciencetechnology
- Accession number :
- edsair.doi.dedup.....1b6a026a09760654984a78ab8d191b4e