Impact of fuel ethanol content on regulated and non-regulated emissions monitored by various analytical techniques over flex-fuel and conversion kit applications

•At 50% vol. of ethanol in the fuel and above the emissions of total unburnt hydrocarbons increase strongly.•The number and size of particles are unaffected by the increase in fuel ethanol content.•Risk of increased NOx emissions for Euro 6d-temp internal combustion engines.•Ethanol content of 50% vol. and above lead to an increase of aldehyde emissions, ethylene, methane, and ethanol.•Both analytical techniques (gas chromatography vs time-resolved mass spectrometry) exhibited similar trends regarding non-regulated emissions. This study evaluates the impact of ethanol content on both regulated and non-regulated emissions with recent vehicle technologies. The three vehicles used here are complying with Euro 6d-temp or Euro 6c emission standards and are adapted to variable ethanol concentrations, either through flex-fuel or E85 conversion kit. Both regulated and non-regulated emissions are characterized to highlight the fuel and vehicle technology impacts. The analysis of non-regulated pollutants in exhaust gases is performed with three different techniques to evaluate their advantages or limitations and assess time-resolved emission levels. HPLC coupled to UV detection to measure aldehydes and ketones. GC–MS was used for PAHs characterization. GC-FID was used to measure VOCs (C1 to C12) on the first phase of the WLTC. FTICR-MS was used to assess time-resolved emission levels. Results indicate a negligible impact on the emissions for ethanol content from 10 to 20% vol. Nevertheless, a significant emission composition variation is observed at 50% vol., and this is even more pronounced with 85% vol. of ethanol. Expected trends based on the literature review are confirmed for all vehicles and this includes an increase in unburned ethanol and aldehydes emissions with higher ethanol content while in this condition lower aromatics contribute to reduce particulate matters emissions. The use of varying amounts of ethanol in recent and diverse Euro 6d-temp vehicle technologies shows that the increase in ethanol content is unaffected by the reduction in particulate emissions and the increase in the finest. However, the results indicate a risk of increased NOx emissions for Euro 6d-temp IC engines, which should be confirmed on other vehicles of similar technology. This study results also indicate that most pollutants are emitted in the engine and exhaust warm-up phase. All analytical techniques exhibited similar trends.