Theoretical and Experimental Study of 3‑Pentanol Autoignition: Ab Initio Calculation, Shock Tube Experiments, and Kinetic Modeling

3-Pentanol
is a potential alternative fuel or a green fuel additive
for modern engines. The H-abstraction reactions from 3-pentanol by
H, CH3, HO2, and OH radicals are significant
in the 3-pentanol oxidation process. However, corresponding rate constants
are forced to rely on either analogy from sec-butanol
or estimation from alkanes due to a lack of direct experimental and
theoretical study. In this work, stationary points on the potential
energy surfaces (PESs) were calculated with the high-level DLPNO-CCSD­(T)/CBS­(T-Q)//M06-2X/cc-pVTZ
method, which is further used to benchmark against the CBS-QB3 method.
Then, the high-pressure limit rate constants for target reactions,
over a broad range of temperature (400–2000 K), were calculated
with the phase-space theory and conventional transition state theory.
A comparison was made between the calculated rate constants and the
values available in Carbonnier et al. [Proc. Combust. Inst. 2019, 37­(1), 477−484]. The rate constants for the above H-abstraction reactions
in the Carbonnier model were updated with the calculated results,
followed by a modification based on the computed results of 3-pentanol
+ HO2 to obtain the revised model. Validation against the
shock tube (ST) and the jet-stirred reactor (JSR) measurements from
the literature proved the revised model an optimal one. Furthermore,
using an ST, ignition delay times (IDTs) for the 3-pentanol/air mixtures
were measured spanning a temperature range of 920–1450 K, pressures
of 6, 10, and 20 bar, and equivalence ratios of 0.5, 1.0, and 1.5.
Generally, IDTs decrease with increasing temperature and reflected
shock pressure. Improved predictions to present experimental data
were obtained by using the revised model as compared with the Carbonnier
model. Finally, sensitivity analysis was conducted using the revised
model to gain an in-depth comprehension of the 3-pentanol autoignition.