Butanol and selective catalytic reduction of gaseous emissions in a heavy-duty diesel engine

The impact of renewable fuels and their blends on vehicle exhaust emissions remains of high interest. In this study, we investigate the effect of butanol on the conversion efficiency of a Selective Catalytic Reduction (SCR) system installed on a commercial Euro V heavy-duty diesel engine (HDDE). Exhaust emissions were measured upstream and downstream of the SCR during dynamometer tests using diesel fuel and various butanol-diesel blends (5/95 %v, 10/90 %v, and 20/80 %v). Steady-state tests according to the World Harmonized Stationary Cycle (WHSC) on an engine bench were conducted including measurements of nitrogen oxides (NOX), total hydrocarbons (THC), and carbon monoxide (CO) emissions utilizing a portable emission measurement system (PEMS). The results showed a reduction in exhaust gas temperature (EGT) of around 4 % for a butanol content of 20 %. The use of butanol increased conversion efficiency of the SCR system by 4 % compared to diesel. The maximum SCR system conversion rate of around 96 % was obtained with a butanol content of 10 %. For all fuels, NOX conversion decreased at high engine loads (above 400 degrees C), while, as expected, was zero at low engine loads (below 200 degrees C). Reductions in CO and THC emissions were observed downstream of the SCR system. In general, this study shows that an SCR originally designed for a Euro V diesel engine can be equally effective when the engine is running on a partial blend of butanol.