Effects of alcohol addition to traditional fuels on soot formation: A review

Soot is one of the main pollutants produced by incomplete combustion of hydrocarbon fuels, which poses a serious threat to human health and the urban environment. Alcohols have been generally considered to be a potential clean fuel to reduce soot emissions. At present, alcohol fuels represented by methanol, ethanol, butanol and pentanol have been extensively studied and have made remarkable progress. Therefore, this article is written as a broad overview of the subject. The effects of methanol, ethanol, butanol and pentanol additions on the formations of soot and polycyclic aromatic hydrocarbons were systematically summarized from the two aspects of the internal combustion engine bench and the fundamental combustion system. These studies have shown a decreasing or synergistic effect of alcohols addition on soot formation and initially revealed the mechanism of soot formation. However, the formation mechanism of soot in complex environments and the mechanism of the effects of alcohols on soot still need to be studied in depth, which can provide more opportunities for humans to reduce soot production during the combustion of hydrocarbon fuels. Finally, some challenges and research suggestions are outlined in the last section of this review.