Quantifying the Decomposition Kinetics of Linear C₂-C₄ Perfluoroalkanes.

Area of Science:

• Physical Chemistry
• Chemical Kinetics
• Combustion Science

Background:

• Perfluoroalkanes are important industrial chemicals with complex decomposition pathways.
• Understanding their pyrolysis is crucial for predicting combustion behavior and environmental fate.
• Previous studies often lacked detailed kinetic data for C2-C4 perfluoroalkanes.

Purpose of the Study:

• To investigate the pyrolysis mechanisms of linear perfluoroalkanes (C2-C4).
• To determine the unimolecular decomposition rate constants for perfluoroethane (PFE), perfluoropropane (PFP), and perfluorobutane (PFB).
• To develop a detailed chemical kinetic model for perfluoroalkane pyrolysis.

Main Methods:

• Laser schlieren densitometry (LS) in a diaphragmless shock tube.
• Shock-heating of perfluoroalkane/krypton mixtures to 1400-2500 K.
• Analysis of density gradient profiles to infer kinetic parameters.

Main Results:

• Carbon-carbon bond fission was identified as the initiation step for all perfluoroalkanes.
• Perfluoroethane and perfluoropropane exhibited one primary dissociation channel.
• Perfluorobutane showed two competing carbon-carbon bond-fission pathways.
• Computed rate constants were integrated into a comprehensive kinetic model.

Conclusions:

• The developed kinetic model accurately simulates the pyrolysis of C2-C4 perfluoroalkanes.
• The study provides critical kinetic data for understanding perfluoroalkane decomposition.
• Findings contribute to improved predictive models for combustion and high-temperature chemistry.