Experimental comparison of carbonyl compounds from a diesel engine fueled with pentanol in blended and fumigation modes

Formaldehyde and acetaldehyde emissions were quantified from an automotive diesel engine (Euro 4) fueled with ultra-low sulfur diesel (ULSD), aged commercial diesel containing 10% (by vol.) of palm oil biodiesel (AB10), a pentanol/ULSD blend, and pentanol fumigated in the air intake manifold. The engine was operated at a fixed load highly representative of urban driving conditions. Exhaust gas samples were gathered with dinitrophenylhydrazine (DNPH) cartridges, extracted with acetonitrile, and analyzed with a high-performance liquid chromatography (HPLC). Results showed that both, fumigation and blending methods used to substitute fossil diesel fuel by pentanol, increased formaldehyde and acetaldehyde emissions compared to ULSD fuel. The way to supply pentanol to the engine (blended or fumigated) drastically impact carbonyl emissions. Pentanol fumigation mode increased 4 times formaldehyde and 34 times acetaldehyde emissions with respect to the pentanol/ULSD blend. On the other hand, aged commercial diesel (AB10) drastically increased formaldehyde emissions. Therefore, a comprehensive evaluation of the benefits of pentanol, whether blended or fumigated should be necessary before promoting oxygenated diesel fuel substitutes, and in addition care must be taken to avoid B10 aging.