Theoretical Kinetics Analysis for Ḣ Atom Addition to 1,3-Butadiene and Related Reactions on the Ċ₄H₇ Potential Energy Surface

Abstract

The oxidation chemistry of the simplest conjugated hydrocarbon, 1,3-butadiene, can provide a first step in understanding the role of polyunsaturated hydrocarbons in combustion and, in particular, an understanding of their contribution toward soot formation. On the basis of our previous work on propene and the butene isomers (1-, 2-, and isobutene), it was found that the reaction kinetics of Ḣ-atom addition to the C═C double bond plays a significant role in fuel consumption kinetics and influences the predictions of high-temperature ignition delay times, product species concentrations, and flame speed measurements. In this study, the rate constants and thermodynamic properties for Ḣ-atom addition to 1,3-butadiene and related reactions on the ĊH potential energy surface have been calculated using two different series of quantum chemical methods and two different kinetic codes. Excellent agreement is obtained between the two different kinetics codes. The calculated results including zero-point energies, single-point energies, rate constants, barrier heights, and thermochemistry are systematically compared among the two quantum chemical methods. 1-Methylallyl (ĊH1-3) and 3-buten-1-yl (ĊH1-4) radicals and CH + ĊH are found to be the most important channels and reactivity-promoting products, respectively. We calculated that terminal addition is dominant (>80%) compared to internal Ḣ-atom addition at all temperatures in the range 298-2000 K. However, this dominance decreases with increasing temperature. The calculated rate constants for the bimolecular reaction CH + Ḣ → products and CH + ĊH → products are in excellent agreement with both experimental and theoretical results from the literature. For selected C species, the calculated thermochemical values are also in good agreement with literature data. In addition, the rate constants for H atom abstraction by Ḣ atoms have also been calculated, and it is found that abstraction from the central carbon atoms is the dominant channel (>70%) at temperatures in the range of 298-2000 K. Finally, by incorporating our calculated rate constants for both Ḣ atom addition and abstraction into our recently developed 1,3-butadiene model, we show that laminar flame speed predictions are significantly improved, emphasizing the value of this study.

The photochemical production of aromatics in the atmosphere of Titan

“…As the flux of the H + C 6 H 5 reaction is 200 times more important than the C 3 H 3 + C 3 H 3 flux, the fulvene and 2-ethynyl-1,3butadiene abundances will be low. Moreover, the H + fulvene and H + 2ethynyl-1,3-butadiene reactions should be relatively fast (around 1.0 × 10 −12 cm 3 molecule −1 s −1 even at 150-200 K), the barrier for the H + fulvene reaction being calculated equal to 7.0 kJ/mol at the M06-2X/AVTZ level (this work) in good agreement with the recent study of H + butadiene by Li et al (2017).…”

A Systematic Theoretical Kinetics Analysis for the Waddington Mechanism in the Low-Temperature Oxidation of Butene and Butanol Isomers

“…Two solvers also showed reasonably good agreement (except the P1 ↔ WDT12 reaction); the difference was found to be 1–2 orders of magnitude, depending on temperature. The very first publication compared the HPL rate constant calculated using the Multiwell and PAPR solvers by Li et al 54 In that paper, some discrepancies were also found between the two solvers. The authors are aware that PAPR is a recently developed solver, indicating that the solver may still require some refinements, compared to MultiWell, The discrepancies obtained in this work constitute useful information which can be communicated to the code developers.…”

Insights into the Reactions of Hydroxyl Radical with Diolefins from Atmospheric to Combustion Environments

“…[18][19][20][21][22][23][24][25] At higher temperatures, only 1,3-butadiene caught the attention of most researchers. 13,26,27 Li et al 26 measured ignition delay times of 1,3-butadiene in a shock tube and a rapid compression machine. Not surprisingly, they observed a clear lack of NTC region due to the suppression of low-temperature reactivity of 1,3 butadiene.…”