Ammonia Production and Utilization in a Hybrid LNT+SCR System

Conference · Thu Jan 01 04:00:00 EST 2009

OSTI ID:967339

Prikhodko, Vitaly Y ^[1]

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1. ORNL

A hybrid LNT+SCR system is used to control NOx from a light-duty diesel engine with in-cylinder regeneration controls. A diesel oxidation catalyst and diesel particulate filter are upstream of the LNT and SCR catalysts. Ultraviolet (UV) adsorption spectroscopy performed directly in the exhaust path downstream of the LNT and SCR catalysts is used to characterize NH3 production and utilization in the system. Extractive exhaust samples are analyzed with FTIR and magnetic sector mass spectrometry (H2) as well. Furthermore, standard gas analyzers are used to complete the characterization of exhaust chemistry. NH3 formation increases strongly with extended regeneration (or over regeneration ) of the LNT, but the amount of NOx reduction occurring over the SCR catalyst is limited by the amount of NH3 produced as well as the amount of NOx available downstream of the LNT. Control of lean-rich cycling parameters enables control of the ratio of NOx reduction between the LNT and SCR catalysts. During lean-rich cycling, fuel penalties are similar for either LNT dominant or LNT with supplemental SCR NOx reduction. However, stored NH3 after multiple lean-rich cycles can enable continued NOx reduction by the SCR after lean-rich cycling stops; thus, requirements for active regeneration of the LNT+SCR system can be modified during transient operation.

• Research Organization: Oak Ridge National Laboratory (ORNL); Fuels, Engines and Emissions Research Center
• Sponsoring Organization: EE USDOE - Office of Energy Efficiency and Renewable Energy (EE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 967339
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
ADSORPTION
AMMONIA
CATALYSTS
CHEMISTRY
DIESEL ENGINES
MASS SPECTROSCOPY
OXIDATION
PARTICULATES
PRODUCTION
REGENERATION
SPECTROSCOPY
TRANSIENTS