Kinetic Model for High-Pressure Methanol Oxidation in Gas Phase and Supercritical Water

A detailed chemical kinetic model
for high-pressure methanol oxidation
in the gas phase and supercritical water (SCW) has been developed,
updating kinetic parameters for key reactions. Based on a careful
analysis of ignition delay measurements for methanol at high pressures
in shock tubes, a rate constant has been derived for reaction CH3OH + HO2. The rate constant is significantly higher
than recent values calculated by high-level theory. Comprehensive
validation of the model was conducted, comparing predictions against
experimental data over a wide range of conditions in both the gas
phase and SCW. Species measurements for methanol oxidation in high-pressure
gas-phase flow reactors (20–100 bar) and ignition delay times
from rapid compression machines and shock tubes (12–50 bar)
were reproduced well by the model. Also, modeling predictions of SCWO
of methanol were generally in agreement with the experiment, with
discrepancies attributed mostly to experimental artifacts such as
hot spots and nonideal hydrodynamics. Based on the model, a comparative
kinetic analysis was conducted to explore the characteristic similarities
and differences of methanol oxidation under the two conditions.