Plasma-Assisted Catalytic Reduction of NOx
WP-1077
Objective
Schematic of Plasma-Assisted SCR Process
The Department of Defense (DoD) needs to develop innovative technologies for reducing nitrogen-base demissions from mobile and stationary sources such as – aircraft engine exhausts, mobile heavy equipment, and diesel generators – to comply with Federal and local regulations arising from the Clean Air Act (CAA) and the CAA Amendments of 1973 and 1990.
This project will further develop and optimize Selective Catalytic Reduction (SCR) technology by using a non-thermal plasma (NTP) pretreatment to augment the oxidation and subsequent catalytic destruction of nitrogen oxides in combustion exhaust gases.
Technical Approach
In the SCR process, destruction of partially oxidized nitrogen-containing contaminants (NOx) present in combustion exhausts proceeds by catalytic oxidation of NOx to nitrogen dioxide (NO2) which is subsequently reduced to nitrogen (N2) by an added reducing agent, usually ammonia or a derivative, in the presence of a second catalyst. Because NOx is oxidized along with hydrocarbons (HC) in an NTP, treating the inflow with the NTP creates reactive species that enhance destruction of NO2 by the SCR catalyst.
Results
A full-scale engineering prototype SCR/NTP system to evaluate the treatment of exhaust from a 6-L diesel engine has been designed and is being assembled in preparation for long-term testing. Projections of the cost/benefit of a full-scale control process are favorable. After initial benchtop studies using propene as the reductant, bench-and pilot-scalestudies on splits of diesel exhaust using diesel fuel as the reductant have achieved less-efficient but still practical conversion of NOx into N2, carbon dioxide (CO2), and water. The extent of NOx conversion appears to be independent of scale, and the process does not appear to be affected by fuel sulfur. A tentative design for a field-ready unit has been prepared.
Benefits
Augmentation of the SCR process by NTP increases the efficiency of removal of NOx and decreases the consumption of power and of added reducing agent. More importantly, it permits use of engine fuel HCs as the reducing agent instead of requiring a separate supply of ammonia or some other nonstandard hazardous material.
Project Documents
Points of Contact
Principal Investigator
Dr. Joseph Wander
AL/EQM (AFRL/MLQE)
Phone: 850-283-6240
Fax: 850-283-6064
Project Documents
Document Types
- Fact Sheet - Brief project summary with links to related documents and points of contact.
- Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
- Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
- Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
- Guidance - Instructional information on technical topics such as protocols and user’s guides.
- Workshop Report - Summary of workshop discussion and findings.
- Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
- Model/Software - Computer programs and applications available for download.
- Database - Digitally organized collection of data available to search and access.