An Ab Initio RRKM-Based Master Equation Study for Kinetics of OH-Initiated Oxidation of 2-Methyltetrahydrofuran and Its Implications in Kinetic Modeling
Cyclic ethers (CEs) can be promising future biofuel candidates. Most CEs possess physico-chemical and combustion indicators comparable to conventional fuels, making them suitable for internal combustion engines. This work computationally investigates the kinetic behaviors of hydrogen abstraction fro...
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MDPI AG
2023-04-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/16/9/3730 |
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| author | Tam V.-T. Mai Thanh Q. Bui Nguyen Thi Ai Nhung Phan Tu Quy Krishna Prasad Shrestha Fabian Mauss Binod Raj Giri Lam K. Huynh |
| author_facet | Tam V.-T. Mai Thanh Q. Bui Nguyen Thi Ai Nhung Phan Tu Quy Krishna Prasad Shrestha Fabian Mauss Binod Raj Giri Lam K. Huynh |
| author_sort | Tam V.-T. Mai |
| collection | DOAJ |
| description | Cyclic ethers (CEs) can be promising future biofuel candidates. Most CEs possess physico-chemical and combustion indicators comparable to conventional fuels, making them suitable for internal combustion engines. This work computationally investigates the kinetic behaviors of hydrogen abstraction from 2-methyl tetrahydrofuran (2MTHF), one of the promising CEs, by hydroxyl radicals under combustion and atmospheric relevant conditions. The various reaction pathways were explored using the CCSD(T)/cc-pVTZ//M06-2X/aug-cc-pVTZ level of theory. The Rice–Ramsperger–Kassel–Marcus-based master equation (RRKM-ME) rate model, including treatments for hindered internal rotation and tunneling, was employed to describe time-dependent species profiles and pressure and temperature-dependent rate coefficients. Our kinetic model revealed that the H-abstraction proceeds via an addition-elimination mechanism forming reaction complexes at both the entrance and exit channels. Eight different reaction channels yielding five radical products were located. The reaction exhibited complex kinetics yielding a U-shaped Arrhenius behavior. An unusual occurrence of negative temperature dependence was observed at low temperatures, owing to the negative barrier height for the hydrogen abstraction reaction from the C-H bond at the vicinity of the O-atom. A shift in the reaction mechanism was observed with the dominance of the abstraction at C<sub>α</sub>-H of 2MTHF ring (causing negative-<i>T</i> dependence) and at CH<sub>3</sub> (positive-<i>T</i> dependence) at low and high temperatures, respectively. Interestingly, the pressure effect was observed at low temperatures, revealing the kinetic significance of the pre-reaction complex. Under atmospheric pressure, our theoretical rate coefficients showed excellent agreement with the available literature data. Our model nicely captured the negative temperature-dependent behaviors at low temperatures. Our predicted global rate coefficients can be expressed as <i>k</i> (<i>T</i>, 760 Torr) = 3.55 × 10<sup>1</sup> × <i>T</i><sup>−4.72</sup> × exp [−340.0 K/<i>T</i>] + 8.21 × 10<sup>−23</sup> × <i>T</i><sup>3.49</sup> × exp [918.8 K/<i>T</i>] (cm<sup>3</sup>/molecule/s). Our work provides a detailed kinetic picture of the OH-initiated oxidation kinetics of 2MTHF. Hence, this information is useful for building a kinetic me chanism for methylated cyclic ethers. |
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| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-11T04:20:20Z |
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| spelling | doaj.art-9e2fa8f104ef4dc4ac85841637a490b62023-11-17T22:50:57ZengMDPI AGEnergies1996-10732023-04-01169373010.3390/en16093730An Ab Initio RRKM-Based Master Equation Study for Kinetics of OH-Initiated Oxidation of 2-Methyltetrahydrofuran and Its Implications in Kinetic ModelingTam V.-T. Mai0Thanh Q. Bui1Nguyen Thi Ai Nhung2Phan Tu Quy3Krishna Prasad Shrestha4Fabian Mauss5Binod Raj Giri6Lam K. Huynh7Institute of Fundamental and Applied Sciences, Duy Tan University, 06 Tran Nhat Duat, Tan Dinh Ward, District 1, Ho Chi Minh City 700000, VietnamDepartment of Chemistry, University of Sciences, Hue University, Hue City 530000, VietnamDepartment of Chemistry, University of Sciences, Hue University, Hue City 530000, VietnamDepartment of Natural Sciences & Technology, Tay Nguyen University, Buon Ma Thuot City 630000, VietnamThermodynamics and Thermal Process Engineering, Brandenburg University of Technology, Siemens-Halske-Ring 8, 03046 Cottbus, GermanyThermodynamics and Thermal Process Engineering, Brandenburg University of Technology, Siemens-Halske-Ring 8, 03046 Cottbus, GermanyPhysical Science and Engineering Division, Clean Combustion Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi ArabiaSchool of Chemical and Environmental Engineering, International University, Quarter 6, Linh Trung Ward, Thu Duc City, Ho Chi Minh City 700000, VietnamCyclic ethers (CEs) can be promising future biofuel candidates. Most CEs possess physico-chemical and combustion indicators comparable to conventional fuels, making them suitable for internal combustion engines. This work computationally investigates the kinetic behaviors of hydrogen abstraction from 2-methyl tetrahydrofuran (2MTHF), one of the promising CEs, by hydroxyl radicals under combustion and atmospheric relevant conditions. The various reaction pathways were explored using the CCSD(T)/cc-pVTZ//M06-2X/aug-cc-pVTZ level of theory. The Rice–Ramsperger–Kassel–Marcus-based master equation (RRKM-ME) rate model, including treatments for hindered internal rotation and tunneling, was employed to describe time-dependent species profiles and pressure and temperature-dependent rate coefficients. Our kinetic model revealed that the H-abstraction proceeds via an addition-elimination mechanism forming reaction complexes at both the entrance and exit channels. Eight different reaction channels yielding five radical products were located. The reaction exhibited complex kinetics yielding a U-shaped Arrhenius behavior. An unusual occurrence of negative temperature dependence was observed at low temperatures, owing to the negative barrier height for the hydrogen abstraction reaction from the C-H bond at the vicinity of the O-atom. A shift in the reaction mechanism was observed with the dominance of the abstraction at C<sub>α</sub>-H of 2MTHF ring (causing negative-<i>T</i> dependence) and at CH<sub>3</sub> (positive-<i>T</i> dependence) at low and high temperatures, respectively. Interestingly, the pressure effect was observed at low temperatures, revealing the kinetic significance of the pre-reaction complex. Under atmospheric pressure, our theoretical rate coefficients showed excellent agreement with the available literature data. Our model nicely captured the negative temperature-dependent behaviors at low temperatures. Our predicted global rate coefficients can be expressed as <i>k</i> (<i>T</i>, 760 Torr) = 3.55 × 10<sup>1</sup> × <i>T</i><sup>−4.72</sup> × exp [−340.0 K/<i>T</i>] + 8.21 × 10<sup>−23</sup> × <i>T</i><sup>3.49</sup> × exp [918.8 K/<i>T</i>] (cm<sup>3</sup>/molecule/s). Our work provides a detailed kinetic picture of the OH-initiated oxidation kinetics of 2MTHF. Hence, this information is useful for building a kinetic me chanism for methylated cyclic ethers.https://www.mdpi.com/1996-1073/16/9/3730ab initioRRKM-ME calculations2-methyl tetrahydrofuranOH radicalskinetic modeling |
| spellingShingle | Tam V.-T. Mai Thanh Q. Bui Nguyen Thi Ai Nhung Phan Tu Quy Krishna Prasad Shrestha Fabian Mauss Binod Raj Giri Lam K. Huynh An Ab Initio RRKM-Based Master Equation Study for Kinetics of OH-Initiated Oxidation of 2-Methyltetrahydrofuran and Its Implications in Kinetic Modeling Energies ab initio RRKM-ME calculations 2-methyl tetrahydrofuran OH radicals kinetic modeling |
| title | An Ab Initio RRKM-Based Master Equation Study for Kinetics of OH-Initiated Oxidation of 2-Methyltetrahydrofuran and Its Implications in Kinetic Modeling |
| title_full | An Ab Initio RRKM-Based Master Equation Study for Kinetics of OH-Initiated Oxidation of 2-Methyltetrahydrofuran and Its Implications in Kinetic Modeling |
| title_fullStr | An Ab Initio RRKM-Based Master Equation Study for Kinetics of OH-Initiated Oxidation of 2-Methyltetrahydrofuran and Its Implications in Kinetic Modeling |
| title_full_unstemmed | An Ab Initio RRKM-Based Master Equation Study for Kinetics of OH-Initiated Oxidation of 2-Methyltetrahydrofuran and Its Implications in Kinetic Modeling |
| title_short | An Ab Initio RRKM-Based Master Equation Study for Kinetics of OH-Initiated Oxidation of 2-Methyltetrahydrofuran and Its Implications in Kinetic Modeling |
| title_sort | ab initio rrkm based master equation study for kinetics of oh initiated oxidation of 2 methyltetrahydrofuran and its implications in kinetic modeling |
| topic | ab initio RRKM-ME calculations 2-methyl tetrahydrofuran OH radicals kinetic modeling |
| url | https://www.mdpi.com/1996-1073/16/9/3730 |
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