A comparative study of the sooting tendencies of various C5–C8 alkanes, alkenes and cycloalkanes in counterflow diffusion flames

Abstract

Highlights Sooting tendencies rankings among different fuels depend on flame conditions. Sooting limits of C 5 –C 8 n-alkane is comparable, regardless of carbon-chain length. Effects of branched fuel structures on sooting tendency kinetically explained. Cyclopentane has even stronger sooting propensity than cyclohexane.

A Review of Recent Research Results on Soot: The Formation of a Kind of Carbon-Based Material in Flames

“…Xu et al (Xu et al, 2020) found that cyclopentane, with a fivemembered ring in the molecule, generated more soot than cyclohexane in counterflow diffusion flames because more odd carbon radicals (cyclopentadienyl and allyl, which are efficient aromatic precursors) were produced in cyclopentane flames. The aliphatic bond between the aromatic sub-units enhances the clustering of PAHs and decreases the dissociation effect due to increasing temperature (Iavarone et al, 2017).…”

A unified reaction network on the formation of five-membered ringed polycyclic aromatic hydrocarbons (PAHs) and their role in ring expansion processes through radical–radical reactions

“…1 Aromatic molecules such as cyclopentanaphthalene isomers (C 13 H 10 ) and fluorene (C 13 H 10 ) carry this five-membered carbon ring backbone and represent basic molecular building blocks of non-planar PAHs like corannulene (C 20 H 10 ) along with nanobowls (C 40 H 10 , C 50 H 10 ) and fullerenes (C 60 , C 70 ). [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Therefore, an untangling of the elementary gas-phase reaction mechanisms toward five-membered ring PAHs is vital in our understanding of the very early chemistry in combustion systems [17][18][19][20][21][22] and in the evolution of carbon-rich circumstellar envelopes of aging Asymptotic Giant branch (AGB) stars such as IRC + 10216 23,24 together with planetary nebulae like TC 1 as their descendants. 5,25 Exploiting crossed molecular beam experiments and chemical microreactor studies augmented by electronic structure calculations, the last decade revealed exciting progress in unraveling gas phase pathways to indene (C 9 H 8 , 1)the simplest aromatic molecule carrying one six-membered plus one five-membered ring (Scheme 1).…”