Valorización electroquímica de CO2 usando un electrodo de difusión de gases cargado con Sn para obtener formiato en disolución acuosa en modo continuo

Abstract

The reduction of the CO2 emissions is necessary to mitigate climate change and for this purpose the valorization of CO2 by electrochemical reduction appears as one of the most interesting option because it allows the conversion of CO2 into industrially useful chemicals. The aim of this work is to study the influence of key variables on the performance of an experimental system for continuous electro-reduction of CO2 to formate with a gas diffusion electrode (GDE), which was made with particles of Sn suspended in a commercial Nafion solution and deposited on carbon paper. This study continues previous works in our research group on electrochemical valorization of CO2 to formate with Pb and Sn plates. A 23 factorial design of experiments at different levels of current density (‘‘j’’), electrolyte flow rate/electrode area ratio (‘‘Q/A ratio’’) and Sn load on the GDE, with the addition of a central point was followed in this paper. The faradaic efficiency and the rate of formate production were obtained to assess the performance. The general results show a similar trend to the plate electrodes on the variables” j” and “Q/A ratio”: an increase in the current density rises the formate rate, at the expense of lowering the efficiency, and rising the “Q/A ratio” improves the efficiency and the rate. Although the trend is similar, with the GDE it was possible to obtain rates two times greater than using Sn plate with efficiencies above 50% and formate concentrations around 400 ppm. The influence of Sn load has the most important effect on rate and efficiency as the statistical analysis showed. Despite these promising results further research is required to optimize the process.