SAE 2014 Light Duty Emissions Control Symposium

Technical Session Schedule

Tuesday, December 9

Lean NOx Control
(Session Code: LDD200)

Room Salon ABCD  11:00 a.m.

Moderators - Rahul Mital, General Motors Co.

Time Paper No. Title
11:00 a.m. ORAL ONLY
Low Temperature SCR Catalysts for Cold Start and Low Load Engine Exhaust Conditions
The main objective of this work is to develop a low-temperature SCR catalyst for the reduction of nitrogen oxides at cold start, low-idle and low-load conditions. A series of metal oxide- incorporated zeolite catalysts were prepared by adopting incipient wetness technique, cation-exchange, deposition-precipitation and other synthesis techniques. The resulting catalysts were characterized and tested for reduction of NOx in a fixed bed continuous flow quartz micro-reactor using ammonia as the reductant gas. Initial catalyst formulations have been achieved optimum NOx reduction activity at low-temperatures. These catalyst formulations showed a maximum NOx conversion in the temperature range of 100 ºC – 350 ºC. Some more experiments were performed with the aim of optimizing these formulations with respect to the metal atomic ratio, preparation method, active components and supported metal type. Further, these catalyst formulations were screened and investigated for reduction of NOx in the broad temperature range between 100 and 600C. Both the preparation method and the relative atomic ratio of metals were found to be critical variables for successful catalyst promotion. The zeolite supported Cu-Ce catalyst prepared by cation-exchange followed by deposition precipitation technique revealed the most promising performance and broadening of the temperature window from 100 to 600 oC. In order to gain fundamental insights which may acquaint further improvements to our catalysts, specific surface area and porevolume measurements, NH3-TPD were performed to: 1) study the relationship between catalyst surface and NOx reduction activity, and 2) investigate the ammonia adsorption/desorption properties at realistic conditions. Finally, the most catalyst was tested for sulfur tolerance and hydrothermal aging studies. The powder micro-reactor time on stream test revealed that the zeolite supported Cu-Ce catalyst demonstrated high sulfur tolerance between 100 and 300 oC in the presence of 100 ppm SO2, 5vol.% H2O and 10 vol.% oxygen in the reaction feed while maintaining stable low temperature NOx activity. It can be ascribed to the preferentially located active component metal ions in the zeolite framework.
Padmanabha Reddy Ettireddy, Adam Kotrba, Tenneco Inc.; Thirupathi Boningari, Panagiotis G. Smirniotis, Univ. of Cincinnati
11:25 a.m. ORAL ONLY
Catalyst Technologies for Cold Start Emission Control
Cold start emission control is critical for light duty vehicles to meet the US EPA Tier 3 or CARB LEV III emission standards. Recent development in this area will be reviewed in this presentation. For stoichiometric-burn gasoline engine powdered vehicles, a gasoline Cold Start Concept (gCSC™) technology will be discussed. The technology integrates HC trapping components and low temperature Three-Way Catalysts together to improve the net HC conversion efficiency. For lean-burn diesel engine powered vehicles, novel diesel Cold Start Concept (dCSC™) catalysts will be presented. The catalysts, in combination with NOx reduction catalysts, can significantly reduce the cold start HC/NOx emissions.
Hai-Ying Chen, Johnson Matthey Inc.
11:50 a.m. ORAL ONLY
NOX Control with Passive SCR in Lean Gasoline Engines
The fuel efficiency of a stoichiometric gasoline engine can significantly be improved by operating the engine in a fuel-lean combustion mode. Reduction of oxides of nitrogen (NOX) emissions in lean exhaust, however, poses a significant technical challenge. The passive NH3-SCR system is a potential low-cost approach for controlling nitrogen oxides (NOX) emissions from lean-burn gasoline engines. In this system, NH3 is generated over a close-coupled TWC during periodic slightly rich engine operation and subsequently stored on an under-floor SCR catalyst. Upon switching to lean, NOX passes through the TWC and is reduced by the stored NH3 on the SCR catalyst. This presentation discusses reductant generation and utilization processes over the passive SCR system and analysis relevant to simulated drive cycles where lean, rich and stoichiometric operations are used to meet engine torque and catalyst emission control demands.
Vitaly Prikhodko, James E. Parks, Josh Pihl, Todd Toops, Oak Ridge National Laboratory
12:15 p.m. Panel
Panel Discussion