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

Coupling nanosecond pulsed plasma with nanocatalysts for efficient CO2
conversion into liquid Chemicals
Liguang Dou1, Yuan Gao1, Yuxuan Xu1, 2, Shuai Zhang1, 2, Tao Shao1,2*

1Beijing International S&T Cooperation Base for Plasma Science and Energy Conversion, Instituteof Electrical Engineering, Chinese Academy of Sciences
2
University of Chinese Academy of Sciencese-mail (speaker): st@mail.iee.ac.cn

Nowadays, there is growing interest into various
strategies to convert CO2 into value-added chemicals.
This is particularly challenging as CO2 is a moleculewith high thermodynamic stability. The integration ofplasma with nanocatalysts is a promising way to improve
the selectivity of liquid oxygenates for CO2 conversion
due to the strong synergy effect[1]. In general, plasma
catalysis has the potential to bypass slow reaction steps
in thermal catalysis through reactive gas phase processes
in the plasma and to improve the selectivity toward
desired products compared to plasma alone due to thepresence of a catalyst. In nonthermal plasma,high-energy electrons (with an average electron
temperature of 1-10 eV) collide with stable molecules
and activate them, while the bulk gas temperatureremains low[2]. Despite the growing research activity inplasma-enhanced catalysis, we still do not fully
understand the relationship between the catalyst
properties and overall reaction performances[3].
In this work, we studied the effect of plasma treatedsupported Co-based catalysts on the CO2 conversion andselectivity of CH3OH during the CO2+H2+H2O system.
Meanwhile, we built a plasma-catalyst model to conduct
zero-dimensional numerical simulations by ZDPlasKin.
This reaction proceeded in a coaxial DBD reactor, inwhich the ground electrode consists of circulating waterand is kept at 10 oC. Combined with the structure
analysis of the catalysts, we observed that Co-based
catalysts with the active CoO sites and abundant oxygen

vacancies can efficiently capture hydroxide radicals(OH) and promote to recombine with CHx radicals toform CH3OH, especially for the H2/Ar plasma treated
CoO catalysts.
The results (Figure 1a) show that no obvious activity canbe observed without plasma due to the thermal stabilityof CO2. Notably, integrating plasma with treated CoO
catalyst can easily drive the CO2 conversion in themixture system (CO2+H2+H2O). As for the products
selectivity (Figure 1b), we can see that the selectivity ofCH3OH was only 16.2% under plasma-only mode. WhenH2O was added, the selectivity of CH3OH increased to20.7%, indicating the promotion effect of H2O onCH3OH synthesis through providing more OH radicals.
Moreover, packing CoO catalyst clearly increased theselectivity of CH3OH from 17.4% to 28.2%,demonstrating that surface reaction greatly contributed tothe CH3OH formation. Impressively, the H2/Ar-CoO
further maximized the selectivity of CH3OH to 39.6%,
implying the importance of the pre-treatment of CoO
catalyst for the selective synthesis of CH3OH.
References[1] George et al, Renew. Renewable and Sustainable
Energy Reviews, 8, 141–173 (2022).
[2] Dou et al, Applied Catalysis B: Environmental, 318,121830 (2022).
[3] Cui, et al, ACS Catalysis, 12, 1326 (2022).

Figure 1. (a) The conversion rates and (b) the selectivity of CH4, CO, CH3OH and C2H5OH over plasma-treated CoO
catalyst in plasma-involved CO2+H2 +H2O system.