Propanol isomers are oxygenated fuels and have higher octane number and energy density compared to methanol and ethanol. In recent years, with the development of fermentation method, propanol isomers have gained more attention as engine additive to reduce the emission and the consumption of traditional fossil fuels. In this study, Hydrocarbon (HC), carbon monoxide (CO) and particulate matter (PM) emission characteristic of propanol isomers/gasoline blends were comparatively investigated at different blending ratios (0, 10, 20, 40 and 100) combined with exhaust gas recirculation (EGR) in a spark-ignition engine. The number distribution of particulate matter emission is mainly studied in addition to the particulate matter mass distribution. Results show that pure propanol isomers yield significantly different emission characteristics compared to the other blends. With the increase of blending ratio, CO emission shows a decreased trend while unidentified HC emissions are observed except pure propanol isomers. And particulate matter number concentration is increased as the increase of propanol isomers proportion. With the introduction of EGR, particulate number concentration and CO emissions decrease. Moreover, n-propanol/gasoline blends produce higher CO and particulate matter number concentration compared to iso-propanol/gasoline blends at the same blending ratio due to their distinctive molecular structures and properties. The experimental results suggest that iso-propanol is more suitable than n-propanol as a gasoline additive within the scope of present experimental condition.
