Reducing Emissions without Sacrificing Performance
Collaboration helps IIC remove roadblocks to cleaner diesel engines
Catalysis research is helping to reduce NOx emissions and diesel pollutants from our roadways.
Take a deep breath of clean, fresh air. Now, you might not think of thanking the Department of Energy, but when it comes to reducing pollutants from the diesel engines on our roadways, it's the DOE that has enabled the basic science and cooperative agreements with private industry to reduce emissions.
The primary culprits in diesel exhaust are soot and NOx, a mixture of nitrogen oxide and nitrogen dioxide. When NOx emissions react with the air, they can form smog and ozone, presenting a serious health risk.
Reducing NOx emissions requires a long-lasting catalyst. On a well-known project, IIC researchers answered how and why a preferred catalyst became unstable. They found that the barium oxide and platinum catalyst, supported on aluminum oxide, morphed into large ineffective particles. Armed with this knowledge, industrial partners Cummins and Johnson Matthey devised materials and new ways of operating the engines that minimized the harmful catalyst changes. This technology is now common on U.S. highways.
In another technological approach to NOx reduction, the IIC team has taken on the challenges of urea selective catalytic reduction or SCR with Ford Motor Company and General Motors. The team determined the different effects of two sulfur compounds – sulfur dioxide and sulfur trioxide – reinforcing the need for ultralow sulfur fuel for these engines to have the required NOx reductions. The team's research also suggested that the performance of the platinum oxidation catalyst upstream of the SCR technology could be significantly improved by adding another precious metal, palladium, which also lowered the system's cost.
IIC researchers performed studies aimed at an understanding of unusual hydrothermal aging of zeolite-based urea SCR catalysts observed by Ford engineers. The aging was shown to severely impact the front edge of the catalyst and change the chemical nature of the front edge such that it would actually generate NOx rather than remove it. These studies were able to identify strategies that the automobile manufacturers could use to prevent these types of problems.
This SCR research resulted in catalysts that are now in use in Ford and GM diesel-powered pickup trucks. In 2014, GM is planning to release a diesel-powered passenger vehicle that uses this catalysis technology for controlling harmful emissions.
This collaboration with industrial partners continues, as IIC scientists are now taking on the challenges presented by new diesel and gasoline engines designed to travel more than 50 miles on a single gallon. "These engines give rise to ridiculously low temperatures in their exhausts. As it is the exhaust temperature that heats the catalyst to make it work, these new high-efficiency vehicles will require different catalysts and emission systems," said Dr. George Muntean, who is leading IIC's research on new materials research for low-temperature, vehicle exhaust emission control.
This work is possible because of the collaborative nature of the IIC. "We truly have a culture of sharing information; we consciously tear down fences and roadblocks that stand in the way of discovery and innovation," said Dr. Charles Peden, IIC Associate Director.
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