Emissions and Emission Controls

Catalysts for Lean Engine Emission Control

Catalysts for controlling NOx from lean engines are studied in great detail at FEERC.  Lean NOx Traps (LNTs) and Selective Catalytic Reduction (SCR) are two catalyst technologies of interest.  Catalysts are studied from the nanoscale to full scale.  On the nanoscale, catalyst powders are analyzed with chemisorptions techniques to determine the active metal surface area where catalysis occurs.  Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy is used to observe the chemical reactions occurring on the catalyst surface during catalyst operation.  Both powder and coated catalyst samples are analyzed on bench flow reactors in controlled simulated exhaust environments to better characterize the chemical processes that are occurring and to support model development.  Unique tools developed at ORNL such as the SpaciMS capillary-based mass spectrometry system allow measurement of the emissions along the catalyst flow axis which greatly enhances the understanding of the chemical processes occurring inside the catalyst.  Finally, catalysts are studied on full scale engines in FEERC engine cells where engines are operated with advanced controls and synergies between catalysts and advanced combustion processes are investigated.

Particulate matter (PM) emissions or soot from lean engines are also problematic due to the stratified charge resulting from direct injection of fuel into the combustion chamber.  To remove the visibly dirty emissions of from diesel engines, diesel particulate filters (DPFs) are used to collect the soot and periodically oxidize (burn) the soot.  ORNL’s efforts in support of PM control date back to the late 1990s when the effects of the sulfur content in fuel on post-catalyst PM emissions was studied.  As a result of the studies, new fuel standards dictating <15 ppm Sulfur content (as compared with the previous standard of <500 ppm) in fuel were enacted in 2007.  The combination of the lower Sulfur fuel and the DPF technology in model year 2007 and beyond diesel Heavy-Duty trucks has decreased PM emissions from those trucks by >95% as compared with pre-2007 models.

Highlights

Technical Highlights October 2015Oct 2015 highlights

Journal Paper to Report the Oak Ridge National Laboratory’s (ORNLs) Recent Discovery of Incompatibility between Diamond-Like Carbon (DLC) and Zinc Dithiophosphate (ZDDP)...