SBIR Phase I: Dual NOX/NH3 Sensor for Diesel Exhaust After-Treatment Systems

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This Small Business Innovation Research Phase I project will investigate the sensing mechanisms underlying a new nitrogen oxides (NOx) sensor technology that also has the potential for ammonia sensing. This project will optimize materials for dual NOx and NH3 sensing through experimentation and testing, establish mechanistic models for both NOx and NH3 sensing, and validate the mechanistic model. Currently commercially available NOx sensors fail to meet the accuracy, response time, and price requirements of these complex after-treatment systems. Ammonia or dual NOx /NH3 sensors are not available commercially. The small business has recently identified an electrocatalytic NOx sensor technology and has demonstrated the potential for significantly improved accuracy, sensitivity, and response time over the commercial technology. Through modification to the sensing electrode materials and sensor operating conditions, this sensor technology has also been demonstrated to be sensitive to ammonia. In this project, the NOx sensing mechanisms will be studied to develop this promising technology into an optimized, robust device. Additionally, the ammonia sensitivity will be investigated to establish a dual NOx /NH3 sensor for the diesel emissions after-treatment market.The broader/commercial impact of this project will be the enhanced ability to monitor NOx, which is a major global pollutant and a precursor to acid rain, and ground-level ozone and smog formation. New environmental regulations are driving NOx emissions to increasingly lower levels, with the most challenging of these being the 2010 EPA Tier 2 diesel tailpipe standards. To meet these, engine manufacturers have been developing new diesel after-treatment technologies including selective catalyst reduction (SCR) systems and lean NOx traps and require both NOx and ammonia sensors for closed loop control and diagnostics of these systems. If successful, the new NOx sensor has the potential to significantly reduce emissions levels of these gases through more accurate and faster detection than the competition. Moreover, the additional NH3 sensitivity offers a solution for monitoring of ammonia slip, an issue for which no commercial sensor currently exists. With a $1.2 billion market forecasted for 2012, the NOx /NH3 sensor has tremendous commercial potential. Additionally, the new sensor technology is expected to be a lower cost approach, enabling the diesel industry to have a sensor that meets both the technical and price requirements.