Using Magnetic Fields to Intensify the CO2 Electrolysis Process

Abstract

Atmospheric CO2 concentrations measured at the ESRL (NOAA, Mauna Loa, HI) have risen to 413 ppm in the past 60 years as a result of addition of about 14.7 Gigatons of net CO2 to the atmosphere per year.1, 2 A fraction of the excess CO2 emissions can be utilized to synthesize carbon-based value-added chemicals (e.g.: CO, ethylene, ethanol) via the electroreduction of CO2 (ECR).3 Prior research efforts have resulted in active and selective catalysts for ECR, however, significant improvements in full cell energy requirement are still needed for ECR to be economically viable at industrial scales.4, 5 Some prior efforts have used magnetic fields as a process intensification tool to improve the electrochemical performance of water electrolysis.6 This talk will cover the use of magnetic fields in CO2 electrolysis to significantly reduce the full cell energy requirement in a gas diffusion electrode-based flow electrolyzer. We demonstrate that the application of a magnetic field leads to a reduction in cell potentials and/or increase in current densities, translating to an improvement in full cell energy efficiencies and reduction in full cell energy requirements. In a 2 M KOH solution, CO partial current densities of 468 mA/cm2 and 345 mA/cm2 were obtained at -3 V cell potential in the presence and absence of a magnetic field, respectively, corresponding to full cell energy savings exceeding 35% due to the application of a magnetic field. A combination of polarization plots and Tafel slope analysis reveals that the reduction in cell potentials and/or increase in current densities is caused by an improvement in the mass transfer of the electroactive species in the electrolyte due to the magnetohydrodynamic effect. References IPCC, Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2013. https://www.esrl.noaa.gov/gmd/ccgg/trends/, (accessed 17 December 2020).O. S. Bushuyev, P. De Luna, C. T. Dinh, L. Tao, G. Saur, J. van de Lagemaat, S. O. Kelley and E. H. Sargent, Joule, 2018, 2, 825-832.B. Endrődi, G. Bencsik, F. Darvas, R. Jones, K. Rajeshwar and C. Janáky, Progress in Energy and Combustion Science, 2017, 62, 133-154.M. Jouny, W. Luc and F. Jiao, Industrial & Engineering Chemistry Research, 2018, 57, 2165-2177.F. A. Garcés-Pineda, M. Blasco-Ahicart, D. Nieto-Castro, N. López and J. R. Galán-Mascarós, Nature Energy, 2019, 4, 519-525.