MODELING COMPETITIVE ADSORPTION IN UREA-SCR CATALYSTS FOR EFFECTIVE LOW TEMPERATURE NOX CONTROL
Although the SCR technology exhibits higher NOx reduction efficiency over a wider range of temperatures among the lean NOx reduction technologies, further improvement in low-temperature performance is required to meet the future emission standards and to lower the system cost. In order to improve the catalyst technologies and optimize the system performance, it is critical to understand the reaction mechanisms and catalyst behaviors with respect to operating conditions. For example, it is well known that the ammonia coverage on catalyst surface is critical for NOx reduction efficiency. However, the level of ammonia storage is influenced by competitive adsorption by other species, such as H2O and NO2. Moreover, hydrocarbon species that slip through the upstream DOC during the cold-start period can also inhibit the SCR performance, especially at low temperatures. Therefore, a one-dimensional detailed kinetic model that can account for the effects of such competitive adsorption has been developed based on steady state surface isotherm tests on a commercial Fe-zeolite catalyst. The model is developed as a C language S-function and implemented in Matlab/Simulink environment. Rate kinetics of adsorption and desorption of each of the adsorbents are determined from individual adsorption tests and validated for a set of test conditions that had all the adsorbents in the feed gas.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 994034
- Report Number(s):
- PNNL-SA-73460; VT0401000; TRN: US201024%%157
- Resource Relation:
- Conference: Proceedings of ASME 2010 International Mechanical Engineering Congress and Exposition (IMECE 2010), Paper No. IMECE 2010-39977
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SELECTIVE CATALYTIC REDUCTION
NITROGEN OXIDES
AIR POLLUTION CONTROL
ADSORBENTS
ADSORPTION
AMMONIA
CATALYSTS
CHEMICAL REACTION KINETICS
PERFORMANCE
ONE-DIMENSIONAL CALCULATIONS
WATER VAPOR
NITROGEN DIOXIDE
HYDROCARBONS
Competitive Adsorption
Hydrocarbon Inhibition
urea-SCR
NOx control
diesel engine
modeling and simulation