Diesel Emission Control-- Sulfur Effects (DECSE) Program-- Phase II Summary Report: NOx Adsorber Catalysts

[摘要] The investigations performed in this project demonstrated the ability to develop a NO{sub x} regeneration strategy including both an improved lean/rich modulation cycle and rich engine calibration, which resulted in a high NO{sub x} conversion efficiency over a range of operating temperatures. A high-temperature cycle was developed to desulfurize the NO{sub x} absorber catalyst. The effectiveness of the desulfurization process was demonstrated on catalysts aged using two different sulfur level fuels. The major findings of this project are as follows: (1) The improved lean/rich engine calibration achieved as a part of this test project resulted in NO{sub x} conversion efficiencies exceeding 90% over a catalyst inlet operating temperature window of 300 C-450 C. This performance level was achieved while staying within the 4% fuel economy penalty target defined for the regeneration calibration. (2) The desulfurization procedure developed showed that six catalysts, which had been exposed to fuel sulfur levels of 3-, 16-, and 30-ppm for as long as 250 hours, could be recovered to greater than 85% NO{sub x} conversion efficiency over a catalyst inlet operating temperature window of 300 C-450 C, after a single desulfurization event. This performance level was achieved while staying within the 4% fuel economy penalty target defined for the regeneration calibration. (3) The desulfurization procedure developed has the potential to meet in-service engine operating conditions and provide acceptable driveability conditions. (4) Although aging with 78-ppm sulfur fuel reduced NO{sub x} conversion efficiency more than aging with 3-ppm sulfur fuel as a result of sulfur contamination, the desulfurization events restored the conversion efficiency to nearly the same level of performance. However, repeatedly exposing the catalyst to the desulfurization procedure developed in this program caused a continued decline in the catalyst's desulfurized performance. Additional work will be necessary to identify the cause of this performance decline. (5) The rate of sulfur contamination during aging with 78-ppm sulfur fuel increased with repeated aging/desulfurization cycles (from 10% per ten hours to 18% per ten hours). This was not observed with the 3-ppm fuel, where the rate of decline during aging was fairly constant at approximately 2% per ten hours.

[发布日期] 2000-10-01 [发布机构] USDOE Office of Heavy Vehicle Technologies, Washington, DC (United States)

[关键词] Nitrogen Oxides;Aging;Diesel Fuels;Desulfurization;Regeneration