Thermal decomposition and oxidation of CH3OH

Area of Science:

• Chemical Kinetics
• Combustion Science
• Atmospheric Chemistry

Background:

• Methanol (CH3OH) is a key intermediate in combustion processes and a potential fuel.
• Accurate kinetic data are crucial for understanding methanol's pyrolysis and oxidation mechanisms.
• Previous experimental data for methanol decomposition rates show significant scatter.

Purpose of the Study:

• To experimentally determine the total decomposition rate of methanol (CH3OH) diluted in Argon (Ar).
• To investigate the oxidation of methanol under various conditions by monitoring hydrogen atom (H) formation.
• To develop an extended reaction mechanism for methanol pyrolysis and oxidation.

Main Methods:

• High-temperature shock tube experiments monitoring H atom concentrations.
• Studying methanol decomposition in Ar at 1359-1644 K.
• Investigating methanol oxidation in mixtures with O2 and Ar at varying concentrations.

Main Results:

• A new rate expression for methanol total decomposition (k1) was determined, showing lower values than previously reported experimental data but consistent with theoretical predictions.
• The branching fraction for the reaction CH3OH + Ar → CH2 + H2O + Ar was quantified as 0.20 ± 0.04 at 1880-2050 K.
• An extended reaction mechanism was developed, accurately predicting H atom evolution in both methanol pyrolysis and oxidation.

Conclusions:

• The study provides crucial kinetic data for methanol combustion.
• The developed reaction mechanism improves the prediction of methanol's behavior in combustion environments.
• The findings contribute to a better understanding of fundamental combustion chemistry.