Theoretical study on iso-pentanol oxidation chemistry: Fuel radical isomerization and decomposition kinetics and mechanism development

This study undertakes a detailed theoretical investigation into the iso-pentanol radical isomerization and decomposition kinetics and the mechanism development of the iso-pentanol oxidation. The CCSD(T)/CBS//M08-HX/6-311+G(2df,2p) method was adopted to calculate the reaction potential energy surface. The reaction rate coefficients were calculated by variational transition state theory (VTST) with multistructural torsional (MS-T) partition function and small curvature tunneling (SCT) correction. Moreover, the pressure-dependent rate coefficients were determined using the system-specific quantum Rice-Ramsperger-Kassel theory (SS-QRRK). The variational and tunneling effects were discussed, and the dominant reaction channels were identified. It reveals that the isomerization reactions play a significant role at low temperatures, while the decomposition reactions dominate the high-temperature regime. Notably, the quantitative rate expressions for iso-pentanol radical decomposition reactions were also obtained. Furthermore, a new kinetic model incorporating the calculated rate coefficients was constructed, exhibiting satisfactory prediction performance on ignition delay times and improved predictive accuracy of species mole fractions. This work provides accurate rate data of isomerization and decomposition kinetics and contributes to a more comprehensive understanding of the iso-pentanol oxidation mechanism.