Table 1.

Literature review on the effect of fuel type on oxidation reactivity of soot

Soot generator	Fuel	Compared with the oxidation reactivity of soot produced by diesel	Reason	Literature report
Diesel engine 1-cylinder	Tri-propylene glycol methyl ether	better	The formed soot had volatile matter, which formed a large number of pores in the process of volatilization and increased the active surface area. Oxygenated fuel promoted the disorder of soot and the increased of the number of carbon atoms at the edge	(Serhan et al. 2018)
	di-propylene glycol methyl ether	better
Diesel engine,2.83L 4-cylinder	soybean oil methyl eater	better	On the one hand, the high oxygen content of biodiesel inhibited the production of polycyclic aromatic hydrocarbons in soot. On the other hand, the high oxygen content contributes to the high porosity of soot, which reduced the activation energy required for soot oxidation	(Du et al. 2022)
	palm oil methyl ester	better
	waste cooking oil methyl ester	better
ASTM D1322 burner	acetone-butanol-ethanol	better	The derived soot of ABE blended fuel contained more aliphatic compounds. These aliphatic chains at the edge of soot could attach more oxygen-containing functional groups to enhance the oxygen content of soot. In addition, the amorphous structure provided more activation points for soot oxidation	(Luo et al. 2018)
Diesel engine,1.99L 4-cylinder	Dimethyl carbonate (DMC)	better	DMC could reduce the formation of soot precursors, which was not conducive to the growth of graphene layer, leading to the disorder of soot particles	(Wei et al. 2020b)
Diesel engine,8.8L	Waste cooking oil (WCO)	better	The soot containing WCO showed a higher degree of disorder and a lower degree of graphitization. Due to the high oxygen content, the O/C ratio, sp3/sp2 ratio and oxygen-containing functional group content of WOC soot were higher than those of diesel	(Hu et al. 2022a)
Diesel engine,8L	biodiesel	-	Nanostructures was proved not to be the only factor affecting the structure of soot. It affected the oxidation reactivity of soot together with soot composition, oxygen content and surface functional groups	(Zhang et al. 2019a)
Diesel engine,8L	Aref	better	Biodiesel derived soot aggregates had less chain orientation and were more disordered in structure than diesel derived soot	(Zhang et al. 2019b)
Diesel engine,2.77L 4-cylinder	N-pentanol	better	The addition of n-pentanol resulted in the decrease of graphitization and the increase of disorder degree of nanostructures	(Wang et al. 2021d)
Diesel engine 4-cylinder	Benzene	better	Compared with pure diesel, the soot nanostructures derived from aromatic mixed fuels become more disordered. Although the oxygen-containing functional groups of soot increase, the high oxygen concentration in the fuel improved the combustion environment, which would form more "mature" soot and reduce the reactivity of soot	(Wang et al. 2020c)
	M-xylene	better
	Tetralin	better
Diesel engine 4-cylinder	Dimethoxymethane	better	Oxygen content improved the purity of graphene and amorphous carbon in soot. In the multi factor sensitivity investigation, nanostructures were considered to play a more important role in the oxidation reactivity of soot than chemical properties	(Pan et al. 2022)
Diesel engine 4-cylinder	Methanol	better	In the comparison between oxygen enriched fuel and pure diesel derived soot, it could be seen that the order of nanostructures was inversely proportional to the reactivity of soot	(Wei et al. 2022)
	Dimethoxymethane	worse

The fuel type includes pure alternative fuel and blend of alternative fuel and diesel. Specific types shall be subject to specific literatures