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

Abstract

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.

Authors:
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:
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)
OSTI Identifier:
1460764
Report Number(s):
NREL/JA-5100-71629
Journal ID: ISSN 1540-7489
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Accepted Manuscript
Journal Name:
Proceedings of the Combustion Institute
Additional Journal Information:
Journal Volume: 37; Journal Issue: 1; Journal ID: ISSN 1540-7489
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; soot; particulate matter; methylcyclohexene; flow reactor; DFT

Citation Formats

Kim, Seonah, Fioroni, Gina M., Park, Ji-Woong, Robichaud, David J., Das, Dhrubajyoti D., John, Peter C.  St., Lu, Tianfeng, McEnally, Charles S., Pfefferle, Lisa D., Paton, Robert S., Foust, Thomas D., and McCormick, Robert L. Experimental and theoretical insight into the soot tendencies of the methylcyclohexene isomers. United States: N. p., 2018. Web. doi:10.1016/j.proci.2018.06.095.
Kim, Seonah, Fioroni, Gina M., Park, Ji-Woong, Robichaud, David J., Das, Dhrubajyoti D., John, Peter C.  St., Lu, Tianfeng, McEnally, Charles S., Pfefferle, Lisa D., Paton, Robert S., Foust, Thomas D., & McCormick, Robert L. Experimental and theoretical insight into the soot tendencies of the methylcyclohexene isomers. United States. doi:10.1016/j.proci.2018.06.095.
Kim, Seonah, Fioroni, Gina M., Park, Ji-Woong, Robichaud, David J., Das, Dhrubajyoti D., John, Peter C.  St., Lu, Tianfeng, McEnally, Charles S., Pfefferle, Lisa D., Paton, Robert S., Foust, Thomas D., and McCormick, Robert L. Mon . "Experimental and theoretical insight into the soot tendencies of the methylcyclohexene isomers". United States. doi:10.1016/j.proci.2018.06.095. https://www.osti.gov/servlets/purl/1460764.
@article{osti_1460764,
title = {Experimental and theoretical insight into the soot tendencies of the methylcyclohexene isomers},
author = {Kim, Seonah and Fioroni, Gina M. and Park, Ji-Woong and Robichaud, David J. and Das, Dhrubajyoti D. and John, Peter C.  St. and Lu, Tianfeng and McEnally, Charles S. and Pfefferle, Lisa D. and Paton, Robert S. and Foust, Thomas D. and McCormick, Robert L.},
abstractNote = {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.},
doi = {10.1016/j.proci.2018.06.095},
journal = {Proceedings of the Combustion Institute},
number = 1,
volume = 37,
place = {United States},
year = {2018},
month = {7}
}

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