### Abstract

Ketenyl radical (HCCO) is an important hydrocarbon combustion intermediate. The mechanisms and kinetics for the reaction of HCCO (X
^{2}
A″) with H(
^{2}
S) occurring on both singlet and triplet surfaces have been studied by a combination of ab initio calculations and rate constant predictions at the CCSD(T)/6-311++G(3df,2p)//CCSD/6-311++G(d,p) level of theory. The kinetics and product branching ratios have been investigated in the temperature range of 297–3000 K by variational transition state and Rice–Ramsperger–Kassel–Marcus (RRKM) theories for the production of CH
_{2}
(a
^{1}
A
_{1}
) + CO(X
^{1}
Σ
^{+}
) and CH
_{2}
(X
^{3}
B
_{1}
) + CO(X
^{1}
Σ
^{+}
). Our prediction for the primary product CH
_{2}
(a
^{1}
A
_{1}
) + CO(X
^{1}
Σ
^{+}
) formation is in good agreement with earlier experimental results. The pressure independent rate constant for this channel can be expressed by k
_{1}
(T) = 8.62 × 10
^{–11}
T
^{0}
^{.16}
exp(–20/T) cm
^{3}
molecule
^{–1}
s
^{–1}
. For the production of CH
_{2}
(X
^{3}
B
_{1}
) + CO(X
^{1}
Σ
^{+}
), the rate constant k
_{2}
can be represented as k
_{2}
(T) = 7.63 × 10
^{–16}
T
^{1.56}
exp(–386/T) cm
^{3}
molecule
^{–1}
s
^{–1}
. The predicted product branching ratios for the reaction are in close agreement with experimental data as well. We also predicted the heat of formation at 0 K for
^{2}
HCCO,
^{3}
CCO, and
^{1}
CCO by CCSD(T)/6-311++G(3df,2p), CBS-QB3, and G2M; the values are in good agreement among one another. Specifically, the CCSD(T) values are: Δ
_{f}
H°(HCCO, X
^{2}
A″) = 42.52 ± 0.70; Δ
_{f}
H°(CCO, X
^{3}
Σ
_{g}
) = 91.50 ± 0.54; and Δ
_{f}
H°(CCO, a
^{1}
Δ) = 110.22 ± 0.54 kcal/mol.

Original language | English |
---|---|

Pages (from-to) | 1095-1114 |

Number of pages | 20 |

Journal | Combustion science and technology |

Volume | 188 |

Issue number | 7 |

DOIs | |

State | Published - 2 Jul 2016 |

### Keywords

- Gas phase reactions
- Hydrocarbon combustion
- Ketenyl radical (HCCO)
- Quantum-chemical calculations

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## Cite this

*Combustion science and technology*,

*188*(7), 1095-1114. https://doi.org/10.1080/00102202.2016.1151878