Reformulation of engine gasoline to reduce emissions in Finnish conditions. Effect of reformulated gasoline on regulated and unregulated exhaust emissions

The research work focused on the comparison of extremely reformulated Cali-fornian gasoline (CARB), current Finnish reformulated gasoline (RFG) and reformulated MTBE- and TAME-containing gasoline (RFG2) with Eurograde gasoline (EN228). The tests were carried out according to the FTP driving cycle at +22 and -7 oC. The fleet of test vehicles comprised 12 passenger cars, seven equipped with a TWC catalyst and five without a catalyst. The tests included regulated exhaust emissions: total hydrocarbons (THC), carbon monoxide (CO) and nitrogen oxides (NOx). In addition, a number of unregulated exhaust emissions were measured: aldehydes, hydrocarbon speciation, ethers, particulates and their composition as well as semivolatile compounds. The fuel consumption was also measured. Significant reductions in exhaust emissions were achieved with all reformulated fuels compared to the Eurograde fuel. For example, the benzene emission was reduced by 40 - 50 % with reformulated fuels for all cars and at both temperatures. The emissions of total toxics were reduced by 14 - 45 % depending on vehicle type and temperature. The THC and CO reductions were higher with RFG and RFG2 gasolines than with CARB gasoline, which was probably due to the low vapour pressure of CARB. The lowest 1,3-butadiene emissions were achieved with CARB gasoline. The preliminary tests indicated that the particulate matter emission from the gasoline-fuelled vehicle equipped with the catalyst was even 1/300 and from the vehicle without the catalyst about 1/10 of that from a diesel-fuelled vehicle. The amount of PAH compounds in the particulate matter from the non-catalyst vehicle was lower with the reformulated fuels than with the Eurograde fuel. The amount of PAH compounds in semivolatile phase also seemed to be reduced with reformulated gasolines. The differences in the consumption of different fuels were insignificant. Even the highest differences were lower than 0.2 l/100 km.