In addition, two vehicles equipped with lean burn, DISI engines were used to test gasoline sulfur effects on the performance of NOx NSR catalysts. Fuels with sulfur levels that varied from 8 ppm to 500 ppm were used. Emissions were evaluated with the Japanese 10-15 mode test cycle. The results from the testing showed that as the sulfur content increased in the fuel, the NOx conversion efficiency deteriorated significantly. The NOx conversion efficiency at 32,000 km using 8 ppm and 30 ppm sulfur fuel was 93% and 82%, respectively. This difference means 2.5 times higher tailpipe NOx emissions for the 30 ppm sulfur fuel (13). The gasoline sulfur impacts on NOx NSR catalysts reported in this work is consistent with the strong sulfur sensitivity observed for NOx storage catalysts evaluated on a variety of light-duty and heavy- duty diesel vehicles.
In the same Toyota study, the reversibility of NOx conversion efficiency of NSR catalysts was investigated. Four catalysts that were aged up to 16,000 km with 8 ppm, 30 ppm, 90ppm and 500 ppm sulfur fuels were prepared. NOx conversion efficiency of each catalyst was measured on an engine dynamometer before and after regeneration of sulfur poisoning. The condition of sulfur regeneration was at 620°C catalyst bed temperature and at an air fuel ratio of 14.0 (rich of stoichiometric). The study showed that the NSR catalyst that was aged with higher sulfur fuel shows lower reversibility. The NOx conversion level of the catalyst aged with 8 ppm sulfur fuel recovered nearly to the fresh condition level after a short regeneration period. However, the NOx conversion efficiency of the NSR catalyst aged with 30 ppm sulfur fuel could not be regenerated to the fresh level after 25 minutes of regeneration.
In addition, two vehicles equipped with lean burn, DISI engines were used to test gasoline sulfur effects on the performance of NOx NSR catalysts. Fuels with sulfur levels that varied from 8 ppm to 500 ppm were used. Emissions were evaluated with the Japanese 10-15 mode test cycle. The results from the testing showed that as the sulfur content increased in the fuel, the NOx conversion efficiency deteriorated significantly. The NOx conversion efficiency at 32,000 km using 8 ppm and 30 ppm sulfur fuel was 93% and 82%, respectively. This difference means 2.5 times higher tailpipe NOx emissions for the 30 ppm sulfur fuel (13). The gasoline sulfur impacts on NOx NSR catalysts reported in this work is consistent with the strong sulfur sensitivity observed for NOx storage catalysts evaluated on a variety of light-duty and heavy- duty diesel vehicles.In the same Toyota study, the reversibility of NOx conversion efficiency of NSR catalysts was investigated. Four catalysts that were aged up to 16,000 km with 8 ppm, 30 ppm, 90ppm and 500 ppm sulfur fuels were prepared. NOx conversion efficiency of each catalyst was measured on an engine dynamometer before and after regeneration of sulfur poisoning. The condition of sulfur regeneration was at 620°C catalyst bed temperature and at an air fuel ratio of 14.0 (rich of stoichiometric). The study showed that the NSR catalyst that was aged with higher sulfur fuel shows lower reversibility. The NOx conversion level of the catalyst aged with 8 ppm sulfur fuel recovered nearly to the fresh condition level after a short regeneration period. However, the NOx conversion efficiency of the NSR catalyst aged with 30 ppm sulfur fuel could not be regenerated to the fresh level after 25 minutes of regeneration.
การแปล กรุณารอสักครู่..