7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Gliding arc plasma-assisted CO2 conversion: Efforts on improving the efficiency
Hao Zhang*, Kaiyi Wang, Yanhui Long, Xiaodong Li, Xin Tu, Jianhua Yan
State Key Laboratory of Clean Energy Utilization,
Institute for Thermal Power Engineering, Zhejiang University
e-mail*: zhang_hao@zju.edu.cn

The conversion of CO2 into value-added chemicals or
fuels has been considered as one of the attractivesolutions for CO2 reduction. However, CO2 is a highly
stable molecule and its activation remains a challenge asa large amount of energy is required for CO2 conversion
in a traditional thermal process. In this regard,
non-thermal plasma has emerged as an attractive
alternative solution as it enables this thermodynamicallyunfavourable reaction (i.e., CO2 activation) to proceedwith a reduced energy cost under mild conditions. Also,
the compactness (high specific productivity) andflexibility(highreaction
rate,
instantaneous‘on-and-off’) of it offers a promising solution to theimbalance between energy production and consumption
by intermittent renewable sources, creating acarbon-neutral network. Various non-thermal plasma
systems have been reported for direct dissociation ofCO2, among which gliding arc discharge is one of themost promising ones because it offers the possibility tooperate at atmospheric pressure and simultaneously
reach a non-equilibrium state that is strong enough tostimulate the most efficient dissociation of CO2 throughvibrational excitation. Nevertheless, efforts on
simultaneously improving the reactant conversion andenergy efficiency in gliding arc assisted CO2 activation
systems are urgently needed.
Our recent efforts show that the efficiency of CO2
conversion in gliding arc plasma can be promisinglyimproved by optimizing the reactor design, coupling
catalysis with plasma, as well as introducing a carbon
bed into CO2 plasma, in addition to optimizing theexperimental conditions. By enhancing the gas treatmentin the plasma area, e.g., via optimization of the injector
nozzle, use of a quadrangular cover, and development ofa magnetically enhanced gliding arc, the CO2 conversion
and energy efficiency can be both improved to someextent [1-2]. Furthermore, for the first time, we
experimentally demonstrate the existence anddetrimental effect of the recombination reaction(CO+O2→CO2) in plasma-assisted CO2 splitting reaction.
Significant enhancement in the performance is thenachieved by inhibiting the recombination reaction,
through e.g., cooling the reactor and introduction ofbiochar to allow for the reverse Boudouard reaction(CO2+C→2CO) [3-4]. Also, we propose a plasma TiO2
photocatalytic strategy that produces a strong
plasma-catalysis synergy for CO2 splitting (only in thein-plasma catalysis mode), improving remarkably thereaction performance [5]. These efforts provide criticalclues for further enhancement of CO2 activation in thepromising plasma processes.

References[1] L. Li, et al. J. CO2 Util., 29, 296 (2019)[2] L. Li, et al. J. CO2 Util., 35, 28 (2020)[3] J. Huang, et al., J. CO2 util., 45, 2021, 101429[4] H. Zhang, et al. ACS Sust. Chem. Eng. 10, 7712,
2022[5] H. Zhang, et al. Waste Disposal & Sustainable
Energy, 2, 139 (2020)

Figure 1 Reaction scheme of the plasmatron-assisted
CO2 reaction with biochar along the reactor [4].

Figure 2 Electron energy distribution function (EEDF) of
the gliding arc discharge and the possible reaction
mechanisms of the plasma photocatalytic CO2
dissociation process [5]