New technology reduces emissions by 50%
Scientists from a US Department of the Environment laboratory have developed the technology to reduce emissions of oxides of nitrogen from a diesel engine by half.
The researchers from the Pacific Northwest National Laboratory are assisting the Partnership for a New Generation Vehicle (PNGV), a joint venture between Ford, General Motors, and DaimlerChrysler, to develop the technology for a new class of vehicles that will travel 80 miles to the gallon and reduce emissions.
The technology was initially discovered accidentally, when scientists investigating the use of an electrically-charged gas, called plasma, for the conversion of oxides of nitrogen to nitrogen gas, found that the packing material in their reactor had an effect on the chemical reaction. “Our scientists began looking at various materials and found a specialised catalyst that selectively reduces oxides of nitrogen,” said Chuck Peden, principal investigator for the project. The initial results found a 70% reduction in NOx emissions, with a significant reduction in soot, “but our lab results over the past six months now show that greater than 90% reduction can be achieved,” he added.
“Six years ago, this field of non-thermal plasma-activated catalysis didn’t exist, but it appears to have many advantages over competing technologies,” said Steve Barlow, a chemical physicist at the laboratory. “For example, our catalysts aren’t poisoned by sulphur in the exhaust, which is a challenge for other catalytic technologies.”
The research team has been working to improve both the electrical discharge designs and the catalyst performance, says Barlow. “One surprising result has been the relative ease with which we have been able to move from the laboratory bench to actual engine testing,” he said. “This gives us confidence in the soundness of our approach.”
Tests using a prototype reactor with a diesel engine have so far shown a 50% reduction of NOx, but continued refinements of the plasma reactor are expected to achieve a greater reduction. “There is more work to be done to reduce the amount of electrical power required to operate the reactor and to increase the overall NOx reduction from 50 to 90% on a real engine,” said Peden.