Combustion process apportionment of carbonaceous particulate emission from a diesel fuel burner

In this study, we present the impact of fuel additives (Fe, Al, and V) on the measured particulate organic matter (OM) fraction formed from the combustion of propane-heated diesel fuel (DF) in a DF Combustion Aerosol STandard (DF-CAST) burner prototype within the range of air-fuel-equivalence ratios (λDF) from 5.4 to 10.4. The OM fraction was measured by using high resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS) and unmixed into factor profiles by applying the SoFi program, a source apportionment tool using positive matrix factorization (PMF)/multilinear engine (ME-2) solvers. The separated factors were correlated with the particle light absorption properties at UV (370 nm) and IR (950 nm) wavelengths, NO3−, and NH4+ as well as exhaust gas (CO2, CO, NO, NH3, hydrocarbons (HC), and formaldehyde (HCHO)). Addition of Fe, Al, and V to the DF yielded apparent catalytic processes leading to the formation of nitrogen-containing particulate OM (CHN and CHON families). The separated factors were distinct in terms of their oxidation state, correlation with the measured particulate and gaseous emissions. Similarities in the separated factors based on temporal evolution were observed in DF and DF+additive experiments. This study gives a new insight in the modification of DF combustion particle properties in the presence of fuel additives.