Influence of potassium on benzene and soot formation in fuel-rich oxidation of methane in a laminar flow reactor

Laser-induced fluorescence for studying the influence of potassium and sodium salts on PAH formation in sooting premixed flames

“…In some earlier studies, it has been shown that chlorine addition tends to increase soot formation [29,30]. In addition, some of the effects of salt addition seem to change with anions (for example, KOH increased particle size [21]), while some others remain the same (for example, catalytic behaviour [18]). Thus, to gain a deeper understanding of the effects of these added salts on soot formation, it is of great value to perform experiments, where the anion in the salt is varied.…”

“…However, an earlier study showed that addition of sodium and potassium salts into premixed ethylene-air flames resulted in smaller soot particles [20]. In another study, addition of KCl and potassium hydroxide (KOH) promoted the formation of acetylene and benzene, while KOH also showed an increase in the soot volume concentration and particle size [21]. Likewise, addition of sodium chloride to flames have shown varying trends for soot concentration (increase [22] and decrease [23]) and soot oxidation (promotion [24] and inhibition [25]).…”

“…Several fundamental studies have been performed in wellcharacterized flames on laboratory burners to investigate the influence of potassium and sodium on soot formation [19][20][21][22][23][24][25][26][27][28]. Addition of KCl to partially premixed ethylene-air flames was found to reduce soot volume fraction while showing negligible effects on primary and sub-primary particle sizes [19].…”

Gas- and Particulate-Phase Emissions from Lab-Scale Flares Experiencing Liquid Carryover

“…This suggests that the alkali metal is much more effective at hindering the combustion process when entrained as NaOH rather than NaCl, and is consistent with the results of previous researchers (Birchall 1970;Rosser et al 1961). Notably, the alkali chloride (NaCl/ KCl) has a higher thermal stability in comparison to that of its hydroxide counterpart (NaOH/ KOH) which can lessen its impact on the radical pool (Du et al 2021).…”

“…The emission of gas-phase species is contingent on the competition between their rates of formation and destruction within the flame. Du et al (2021) showed that in a methane laminar flow reactor at fuel-rich conditions benzene formed at a greater rate from the introduction of alkali metals, specifically potassium (K) in the form of KCl and KOH. Surprisingly, this increase in benzene formation was attributed to potassium actually increasing the concentration of OH radicals in the flame, which help promote the formation of benzene precursors, namely methyl and vinyl radicals.…”