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Title: Experimental and theoretical insight into the soot tendencies of the methylcyclohexene isomers

The formation of soot precursors during combustion of three positional isomers of methylcyclohexene was investigated in flow reactor experiments and through density functional theory simulations. As evidenced by a recently published structure-property model, the sooting tendencies of these compounds differ from those of structurally similar molecules - suggesting new or unusual reaction chemistry. It was demonstrated that 1-methyl-1-cyclohexene and 4-methyl-1-cyclohexene preferentially react via a retro-Diels-Alder pathway leading to ring opening and molecular weight reduction. 3-methyl-1-cyclohexene, which exhibits much higher yield sooting index, preferentially reacts via dehydrogenation to cyclohexadienes and toluene - consistent with higher soot formation. It was demonstrated that the relative stability of the first radical intermediate plays a considerable role in determining the branching ratio between formation of soot precursors and ring opened retro-Diels-Alder reaction products. This study underscores the importance that small structural features can have in determining the ultimate fate of carbon during combustion processes.
ORCiD logo [1] ;  [1] ; ORCiD logo [2] ;  [1] ; ORCiD logo [3] ;  [1] ;  [2] ; ORCiD logo [3] ;  [3] ;  [4] ;  [1] ; ORCiD logo [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Univ. of Connecticut, Storrs, CT (United States)
  3. Yale Univ., New Haven, CT (United States)
  4. Univ. of Oxford (United Kingdom); Colorado State Univ., Fort Collins, CO (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 1540-7489
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Proceedings of the Combustion Institute
Additional Journal Information:
Journal Name: Proceedings of the Combustion Institute; Journal ID: ISSN 1540-7489
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B)
Country of Publication:
United States
09 BIOMASS FUELS; soot; particulate matter; methylcyclohexene; flow reactor; DFT
OSTI Identifier: