Kinetic Analysis for Reaction of Cyclopentadiene with Hydroperoxyl Radical under Low- and Medium-Temperature Combustion.

The kinetic data of cyclopentadiene CH oxidation reactions are significant for the construction of aromatics oxidation mechanism because cyclopentadiene CH has been proved to be an important intermediate in the aromatics combustion. Kinetics for the elementary reactions on the potential energy surface (PES) relevant for the CH + HO reaction are studied in this work. Stationary points on the PES are calculated by employing the CCSD(T)/cc-pVTZ//B3LYP/6-311G(d,p) level of theory. High-pressure limit and pressure-dependent rate constants for elementary reactions on this PES are calculated using conventional transition state theory (TST), variational transition-state theory (VTST) and Rice-Ramsberger-Kassel-Marcus/master equation (RRKM/ME) theory. In this work, the reaction channels for the CH + HO reaction which include H-abstraction channels from CH by HO to form the CH + HO and the addition channels through well-skipping pathways to form the bimolecular products CH + O or CHO + OH, or through CHO stabilization and its unimolecular decomposition to form the bimolecular products CH + O or CHO + OH, namely sequential pathways, are studied. Also, the consuming reaction channels for the compounds CHO and CH in the addition products are studied. The dominant reaction channels for these reactions are unraveled through comparing the energy barriers and rate constants of all elementary reactions and it is found: (1) HO addition to cyclopentadiene CH is more important than direct H-abstraction. (2) in the HO addition channels, the well-skipping pathways and sequential pathways are competing and the well-skipping pathways will be favor in the higher pressures and the sequential pathways will be favor in the higher temperature. (3) The major consumption reaction channel for the five-member-ring compound CHO is the reaction channel to form CH + CO and the major consumption reaction channel for the five-member-ring compound CH is the reaction channel to form CH + CH. High-pressure limit rate constants and pressure-dependent rate constants for elementary reactions on the PES are calculated, which will be useful in modeling the oxidation of aromatic compounds at low- and medium-temperatures.