Experimental study on the durability of biodiesel-powered engine equipped with a diesel oxidation catalyst and a selective catalytic reduction system

This study aims to investigate the effect of durability on the regulated and unregulated emissions, as well as the power and fuel economy performance of a biodiesel-powered engine equipped with a diesel oxidation catalyst (DOC) and a selective catalytic reduction (SCR) system based on a 500-h durability test. Furthermore, a BET (Brunauer-Emmett-Teller) test was employed to analyze the specific surface area changes of the DOC and SCR. Results show that after the durability, the power performance improved and the brake-specific fuel consumption (BSFC) reduced due to the running-in effect. Although the deterioration of the DOC and SCR after the durability resulted in an increase in the carbon monoxide (CO), total hydrocarbon (THC) and nitrogen oxide (NOX) emission factors of the biodiesel-powered engine based on European steady state cycle (ESC) by 41.3%, 36.1% and 39.2%, respectively, these emissions were still below China-Ⅴ limits. For unregulated emissions, the reduced BSFC caused by the durability led to a decrease in the carbon dioxide (CO2) and sulfur dioxide (SO2) emissions, but the durability resulted in higher aldehyde emission. The BET specific surface areas of the DOC and SCR decreased by 40.2% and 35.0%, respectively after the durability, which accounted for their catalytic performance deterioration.