Pressure-dependent kinetics of peroxy radicals formed in isobutanol combustion
Bio-derived isobutanol has been approved as a gasoline additive in the US, but our understanding of its combustion chemistry still has significant uncertainties. Detailed quantum calculations could improve model accuracy leading to better estimation of isobutanol's combustion properties and its...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Royal Society of Chemistry (RSC)
2020
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| Online Access: | https://hdl.handle.net/1721.1/127820 |
| _version_ | 1826188536643059712 |
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| author | Goldman, Mark Jacob Yee, Nathan Wa-Wai Kroll, Jesse Green Jr, William H |
| author2 | Massachusetts Institute of Technology. Department of Civil and Environmental Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Civil and Environmental Engineering Goldman, Mark Jacob Yee, Nathan Wa-Wai Kroll, Jesse Green Jr, William H |
| author_sort | Goldman, Mark Jacob |
| collection | MIT |
| description | Bio-derived isobutanol has been approved as a gasoline additive in the US, but our understanding of its combustion chemistry still has significant uncertainties. Detailed quantum calculations could improve model accuracy leading to better estimation of isobutanol's combustion properties and its environmental impacts. This work examines 47 molecules and 38 reactions involved in the first oxygen addition to isobutanol's three alkyl radicals located α, β, and γ to the hydroxide. Quantum calculations are mostly done at CCSD(T)-F12/cc-pVTZ-F12//B3LYP/CBSB7, with 1-D hindered rotor corrections obtained at B3LYP/6-31G(d). The resulting potential energy surfaces are the most comprehensive isobutanol peroxy networks published to date. Canonical transition state theory and a 1-D microcanonical master equation are used to derive high-pressure-limit and pressure-dependent rate coefficients, respectively. At all conditions studied, the recombination of γ-isobutanol radical with O₂ forms HO₂ + isobutanal. The recombination of β-isobutanol radical with O₂ forms a stabilized hydroperoxy alkyl radical below 400 K, water + an alkoxy radical at higher temperatures, and HO₂ + an alkene above 1200 K. The recombination of β-isobutanol radical with O₂ results in a mixture of products between 700–1100 K, forming acetone + formaldehyde + OH at lower temperatures and forming HO₂ + alkenes at higher temperatures. The barrier heights, high-pressure-limit rates, and pressure-dependent kinetics generally agree with the results from previous quantum chemistry calculations. Six reaction rates in this work deviate by over three orders of magnitude from kinetics in detailed models of isobutanol combustion, suggesting the rates calculated here can help improve modeling of isobutanol combustion and its environmental fate. |
| first_indexed | 2024-09-23T08:00:50Z |
| format | Article |
| id | mit-1721.1/127820 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T08:00:50Z |
| publishDate | 2020 |
| publisher | Royal Society of Chemistry (RSC) |
| record_format | dspace |
| spelling | mit-1721.1/1278202022-09-23T10:18:51Z Pressure-dependent kinetics of peroxy radicals formed in isobutanol combustion Goldman, Mark Jacob Yee, Nathan Wa-Wai Kroll, Jesse Green Jr, William H Massachusetts Institute of Technology. Department of Civil and Environmental Engineering Massachusetts Institute of Technology. Department of Chemical Engineering Bio-derived isobutanol has been approved as a gasoline additive in the US, but our understanding of its combustion chemistry still has significant uncertainties. Detailed quantum calculations could improve model accuracy leading to better estimation of isobutanol's combustion properties and its environmental impacts. This work examines 47 molecules and 38 reactions involved in the first oxygen addition to isobutanol's three alkyl radicals located α, β, and γ to the hydroxide. Quantum calculations are mostly done at CCSD(T)-F12/cc-pVTZ-F12//B3LYP/CBSB7, with 1-D hindered rotor corrections obtained at B3LYP/6-31G(d). The resulting potential energy surfaces are the most comprehensive isobutanol peroxy networks published to date. Canonical transition state theory and a 1-D microcanonical master equation are used to derive high-pressure-limit and pressure-dependent rate coefficients, respectively. At all conditions studied, the recombination of γ-isobutanol radical with O₂ forms HO₂ + isobutanal. The recombination of β-isobutanol radical with O₂ forms a stabilized hydroperoxy alkyl radical below 400 K, water + an alkoxy radical at higher temperatures, and HO₂ + an alkene above 1200 K. The recombination of β-isobutanol radical with O₂ results in a mixture of products between 700–1100 K, forming acetone + formaldehyde + OH at lower temperatures and forming HO₂ + alkenes at higher temperatures. The barrier heights, high-pressure-limit rates, and pressure-dependent kinetics generally agree with the results from previous quantum chemistry calculations. Six reaction rates in this work deviate by over three orders of magnitude from kinetics in detailed models of isobutanol combustion, suggesting the rates calculated here can help improve modeling of isobutanol combustion and its environmental fate. National Science Foundation (Grants 1709993, 1122374) 2020-10-06T22:19:06Z 2020-10-06T22:19:06Z 2020-08 2020-05 2020-09-18T17:27:55Z Article http://purl.org/eprint/type/JournalArticle 1463-9084 1463-9076 https://hdl.handle.net/1721.1/127820 Goldman, Mark Jacob et al. "Pressure-dependent kinetics of peroxy radicals formed in isobutanol combustion." Physical Chemistry Chemical Physics (August 2020): 19802-19815 en http://dx.doi.org/10.1039/d0cp02872j Physical Chemistry Chemical Physics Creative Commons Attribution 3.0 unported license https://creativecommons.org/licenses/by/3.0/ application/pdf Royal Society of Chemistry (RSC) Royal Society of Chemistry (RSC) |
| spellingShingle | Goldman, Mark Jacob Yee, Nathan Wa-Wai Kroll, Jesse Green Jr, William H Pressure-dependent kinetics of peroxy radicals formed in isobutanol combustion |
| title | Pressure-dependent kinetics of peroxy radicals formed in isobutanol combustion |
| title_full | Pressure-dependent kinetics of peroxy radicals formed in isobutanol combustion |
| title_fullStr | Pressure-dependent kinetics of peroxy radicals formed in isobutanol combustion |
| title_full_unstemmed | Pressure-dependent kinetics of peroxy radicals formed in isobutanol combustion |
| title_short | Pressure-dependent kinetics of peroxy radicals formed in isobutanol combustion |
| title_sort | pressure dependent kinetics of peroxy radicals formed in isobutanol combustion |
| url | https://hdl.handle.net/1721.1/127820 |
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