A diesel-emissions control system that is said to be able to reduce nitrogen oxide (NOx) emissions up to 95% has been developed by a collaboration between Tenneco (tenneco.com), GE Transportation (getransportation.com) and Umicore (umicore.com). The technology, Hydrocarbon Lean NOx Catalyst (HC-LNC), features a unique silver-based catalyst with an engineering nanostructure, which was developed by GE. This silver-based catalyst differs from most selective catalytic reduction (SCR) after treatment systems that typically use copper or iron-based catalysts.
Other components include a diesel particulate filter, vaporizer, dosing system, injector, and Tenneco’s Thermal Regeneration Unit for Exhaust (T.R.U.E.-Clean) combustion sensing technology.
If straight diesel is run through the system, emissions are reduced by 65%. However, adding E85 (85% ethanol, 15% gasoline) as the reductant is said to reduce emissions up to 95%. E85 is both volatile and has a high oxygen content, which are believed to be factors in this emissions reduction.
“The reductant is vaporized, sprayed in vapor form on the catalyst,” explains Tim Jackson, Tenneco Chief Technology Officer. “The vapor basically reacts on the base of the catalyst with the NOx and reduces it to harmless nitrogen and water vapor.”
The E85 reductant also offers several advantages over the more commonly used urea. According to Jackson, it’s widely available, has a longer shelf life, is less corrosive, doesn’t freeze and operates in the HC-LNC system with reduced dosing rates, which extend refill intervals.
Jackson says the system is being developed for commercial launch in January 2012 to comply with future EPA standards. “The nice thing about this technology is it’s scalable,” he says. “So we can use it on engines as small as 30 hp to as large as 400 hp.”—EF