Low Cost Retrofil Emissions Control In Off-Road Sources

This Small Business Innovative Research (SBIR) program addresses the development of catalyst technology for passive, lean abatement of nitrogen oxides (NOx) from off-road diesel exhaust sources. The approach utilizes passive reduction of NOx with exhaust-borne, oxidizable species under the fuel lean conditions encountered in diesel exhaust. Although a number of technologies exist for NOx abatement, the state-of-the-art technologies are the lean NOx storage and release trap (NSR) and catalytic removal of nitrogen oxides from mobile diesel exhausts by selective catalytic reduction (SCR) with urea. Although these approaches have been intensively investigated, they exhibit shortcomings in that they require additional hardware, impose costs for reagent use and storage, and waste resources (urea or fuel) as well. Furthermore: 1) NOx traps require low-sulfur fuels (and fuel supplementation) for effective use, and 2) existing lean NOx catalysts generally achieve less than 20% reduction in NOx emissions. A catalyst not requiring reagent or fuel supplementation is an extremely attractive and flexible option. Consequently, the key objective of the program is development of an inexpensive but effective sulfur oxides-tolerant, reagentless (passive) lean NOx catalyst. In Phase I, Eltron identified specific, innovative, passive lean NOx catalyst compositions possessing exceptional activity (e.g., exhibiting 35-50% removal of NOx from real diesel exhaust) for NOx reduction by exhaust-borne hydrocarbons in diesel exhaust. Tests of preferred catalysts in diesel exhaust absent supplemental reductant gave activity with reduction of exhaust NOx level (to < 1.5g/bhp•hr, engine load weighted) at low cost. Phase II will involve validation of Phase I results, final optimization of catalysts for non-highway diesel applications, and more extensive testing of catalysts in real exhausts. Catalyst development will continue to the point of engineering, fabricating, and testing monolithic structures incorporating the preferred catalyst. The end result of Phase II will be a catalyst technology that is commercially ready and outperforms or·augments existing technologies while minimizing capital and operating costs as well as the waste associated with current technologies. Successful completion of this program will result in catalysts applicable to a passive, lean exhaust after-treatment technology for removing nitrogen oxides and other species from exhaust streams rich in sulfur oxides. The technology will be applicable to after-treatment of exhausts from diesel engines, lean burn gasoline engines, natural gas-fired boilers and turbines, and coal-fired combustion sources. In addition to helping improve air quality, the reduction in costs and wastes will enable industry to more cost-effectively operate and address regulatory mandates.