Mechanistic study on nonthermal plasma conversion of CO2
Dimas Adrianto, Zunrong Sheng, Tomohiro Nozaki*
* The author to whom correspondence should be addressed.
Department of Mechanical Engineering, Tokyo Institute of Technology, Tokyo, Japan
Abstract
Dielectric barrier discharge (DBD) was generated in a wide range of electric field from 60 to 700 Td by adjusting the operating pressure and the gas gap for the parametric study of electron impact reaction on CO2 dissociation. Moreover, the effect of specific energy input (SEI) was clarified in terms of CO2 conversion as well as energy efficiency. The results show that CO2 conversion efficiency increased at higher pressure, while low-pressure operation showed a negligible effect, indicating that generation of vibrational species followed by vibration-to-vibration (V–V) energy transfer, known as ladder-climbing dissociation mechanism, provides a more efficient pathway than electron impact direct CO2 dissociation reaction. CO2 conversion increases linearly with SEI because energy input per molecule increases. However, energy conversion efficiency decreases by SEI, showing a clear trade-off between CO2 conversion and energy efficiency: such a trade-off relationship is correlated with ladder-climbing dissociation mechanism. Electron impact reaction process was further studied by BOLSIG+, electron Boltzmann equation solver, to gain deep insight into the electronic activation CO2 in DBD type nonthermal plasma.
Keywords - CO2 activation, nonthermal plasma, dielectric barrier discharge, vibrational excitation, ladder-climbing dissociation.
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