Non-equilibrium Microwave Plasma for Efficient High Temperature Chemistry

Area of Science:

• Plasma chemistry
• Chemical reaction engineering

Background:

• Non-equilibrium chemistry enables efficient molecular transformations.
• Flowing plasma reactors offer continuous processing with rapid startup.
• Stable molecules like CO2, N2, and CH4 are targets for plasma-based activation.

Purpose of the Study:

• To present a microwave plasma methodology for converting electrical energy into molecular energy modes.
• To drive non-equilibrium chemistry efficiently.
• To demonstrate the conversion of CO2 to CO as a model system.

Main Methods:

• Utilizing a flowing microwave plasma reactor.
• Employing laser (Rayleigh) scattering for temperature measurement.
• Using Fourier Transform Infrared Spectroscopy (FTIR) for in situ vibrational excitation and effluent analysis.

Main Results:

• Demonstrated conversion of CO2 to CO, exceeding thermodynamic equilibrium.
• High vibrational excitation achieved, driving non-equilibrium conditions.
• Continuous process capability with second-timescale startup demonstrated.

Conclusions:

• Microwave plasma is effective for driving non-equilibrium chemistry.
• High vibrational excitation is key to exceeding equilibrium conversion.
• The methodology is suitable for activating stable molecules like CO2.