Influence of n-Butanol Addition on C<sub>3</sub>H<sub>3</sub> Formation in n-Butane Combustion
 —The effects of different n-butanol blending ratios (Rb) on the formation of propargyl radical (C3H3), an important benzene precursor, during the combustion of n-butanol/n-butane blends are studied. A detailed kinetic combustion model of n-butanol/n-butane is developed and the premixed n-butanol/n-butane flames are calculated at an equivalence ratio of 1.5, an initial pressure of 1.0 atm, and a temperature range from 800 to 2000 K in a perfectly stirred reactor (PSR), with Rb varying from 0 to 1.0. The results show that under the investigated conditions, the peak value of the mole fraction of C3H3 decreases non-linearly with the increase of Rb. Due to the interaction between combustion products of n-butane and n-butanol during the combustion process, the actual peak mole fraction of C3H3 is higher than the theoretical value. A rate of production (ROP) analysis reveals that the number of β-carbon atoms in the molecule of n-butane and n-butanol affects the efficiency of H-abstraction reactions in generating 2-butyl (sC4H9) and C4H8OH-3 (CH3–*CH–CH2–CH2–OH), which are the two major original sources of C3H3. For both n-butane and n-butanol, the main pathway of forming C3H3 from propene (C3H6) is basically the same, which is C3H6 → C3H5-a (symmetric allyl radical) → C3H4-a (allene) → C3H4-p (propyne) → C3H3. When Rb ranges from 0.4 to 0.6, the deviation degrees of the peak mole fraction of the involved C3 species reach a maximum, indicating that the interaction between the two fuels is the most significant. The non-linear decrease in the mole fraction of C3H3 can attribute to three reasons: (a) the increase of Rb promotes the increase of the conversion ratios of n-butane to sC4H9 and n-butanol to C4H8OH-3; (b) the contribution ratios of the reactions involved in the C3H5-a → C3H4-a → C3H4-p → C3H3 pathway decrease with increasing Rb (c) C3H5-t (tertiary allyl radical) → C3H4-p → C3H3 is the secondary pathway for the formation of C3H3. With the increase of Rb, the dependence of C3H4-p on C3H5-t increases and the conversion ratio of C3H5-t to C3H4-p increases. This study investigates the non-linear decrease of the mole fraction of C3H3 by revealing the interactions between n-butanol and n-butane during the combustion, which can help better understand the effect of n-butanol on the formation of benzene. 