Membranas sostenibles de intercambio aniónico para aplicaciones electroquímicas : preparación y caracterización

Abstract

Ion exchange membranes (IEMs) are used in many applications related with sustainable development. In particular, they are currently investigated in the conversion of CO2 to high added value products as a way of mitigating climate change. Employing low-cost or renewable polymers, as well as non-toxic inorganic fillers in the synthesis of new membranes is also a way of improving the sustainability of the process. In this work, ion exchange membranes based on a polymeric blend of chitosan and poly(vinyl) alcohol were prepared. We have characterized the most relevant properties related to the behavior of IEMs in an electrochemical devise: ion exchange capacity (IEC), conductivity, and some hydrophilic properties by the water uptake (WU) and the water vapor permeability (WVP). We have studied the influence of adding different loads of diverse fillers containing copper, as this metal is the main catalyst for the electro-reduction of CO2 to CH4: unsupported Cu nanoparticles, Cu-exchanged nanoporous layered titanosilicate AM-4 and stannosilicate UZAR-S3, and zeolites Y, MOR and BEA, in order to facilitate the membrane fabrication process and the mechanical stability of the resulting membranes. Every property characterized was compared with the results given by a commercial membrane, the FAA-3 from Fumatech GmbH. The results of the characterization showed that the best-prepared IEM was the one containing 10 % wt. of Cu-AM4. In addition, an analysis of variance was performed to explain the effects of the type of filler and the load applied to the physico-chemical properties studied. This analysis determined that the electrochemical properties of the membranes are noticeably affected by both the type and load of filler, but the hydrophilic properties are more influenced by the polymers. Viscosity and porosity of the membrane have more significant effects in the water sorption and transport properties.