Effectiveness of Selective Catalytic Reduction ( SCR ) systems on 1 reducing gaseous emissions from an engine using Diesel and Biodiesel 2 Blends 3 4

32 There is an urgent and pressing need to further understand petroleum-based emission 33 control systems. To date, a limited number of emission studies have reported on the 34 effects on automotive emissions when vehicles equipped with Selective Catalytic 35 Reduction (SCR) systems run on a mixture of regular petroleum-based and biodiesel. 36 The aim of this investigation was to quantify organic and inorganic gas emissions from 37 a four-cylinder diesel engine equipped with urea-SCR system. Using a bench 38 dynamometer, the emissions from the following mixtures were evaluated using an 39 FTIR spectrometer: low sulphur diesel (LSD), ultra-low sulphur diesel (ULSD) and a 40 blend of 20 % soybean biodiesel and 80% ULSD (B20). Our results confirmed that the 41 use of the SCR system yields statistically significant (p<0.05) lower NOx emissions in 42 comparison to all the studied fuels. The LSD and ULSD fuels also significantly reduced 43 emissions of compounds with high photochemical ozone creation potential, such as 44 formaldehyde. However, the SCR system produced significantly (p<0.05) higher 45 emissions of N2O comparing the used fuels. In the case of LSD, the NH3 emissions 46 were elevated and in the case of ULSD and B20 fuels, the non-methane hydrocarbon 47 (NMHC) and total hydrocarbon (HCD) emissions were significantly higher. 48 49