Synergetic effect of microwave plasma and catalysts in CO2 methanation

Abstract

The reduction of CO2 concentration in our atmosphere consists in a big challenge for researchers, who are trying to explore novel technologies in order to transform CO2 into high added-value products. CO2 conversion into methane using microwave plasma (MWP) manifests as a very promising solution due to the ease of transport of methane and its storage. Microwave plasma represents a source of high-energy electrons, active ions and radicals that enhance or enable chemical reaction. It can be supplied by electricity generated from renewable resources. Then, MWP does not require any electrode to be generated and thus, the cost of those electrodes and of maintenance is reduced compared to glow discharge or DBD plasmas. MWP also can be generated over wide range of pressure (between 10 mbar-1bar). In addition, in the case of MWP, more electrons and active species are produced in comparison with other type of plasma[1–4]. MWP is a very suitable medium for this chemical reaction and leads to an efficient dissociation of CO2. The catalytic reduction of CO2 with H2 using MWP has been investigated in this work and the synergetic effects between the plasma and several catalysts were studied. First, the reaction was carried out without any catalysts and the effect of CO2/H2 ratio, total flow rate and input energy were evaluated. Then, a microwave generated plasma process was coupled with several Nickel catalysts that we prepared and characterized [5] in order to lead the reaction into methane formation. Multiple configurations were studied by changing the position of the catalyst bed. Obtained results were compared with conventional catalytic tests made with the same catalysts. It was found that the conversion of CO2 and energy efficiency increased using plasma assisted catalytic methanation of CO2 in comparison with conventional process. Operating conditions were studied in order to optimize methane production and energy efficiency of Plasma-catalytic process.   References Qin, Y., G. Niu, X. Wang, D. Luo, Y. Duan, J. CO2 Util., 2018, 28, 283–291. De la Fuente, J.F., S.H. Moreno, A.I. Stankiewicz, G.D. Stefanidis, Int J Hydrogen Energy, 2016, 41, 21067–21077. Ashford, B., X. Tu, Curr Opin Green Sustain Chem, 2017, 3, 45–49. Vesel, A., M. Mozetic, A. Drenik, M. Balat-Pichelin, Chem Phys., 2011, 382, 127–131. Alrafei, B., I. Polaert, A. Ledoux, F. Azzolina-Jury, Catal. Today, Available online 12 March 2019, In Press, Accepted Manuscript. https://doi.org/10.1016/j.cattod.2019.03.026