Synthesis of anion exchange membranes and ionomers for application in electrochemical conversion devices

Abstract

Climate issues and the need to reduce emissions of environmentally harmful gases have driven demand for clean energy sources. In this context, hydrogen energy and fuel cells play an important role. On the other hand, to meet the energy demand, the production of fossil fuels is still the majority and it has as its main byproduct the methane gas. Methane electrochemical converters are an interesting technology for mitigating the potential effects of gas emissions, with concomitant energy production. In the context of producing clean energy and/or minimizing the effects of harmful gases from fossil fuels, this project intends to meet these expectations from the development of Anion Exchange Membranes (AEMs) to be used as solid electrolyte in electrochemical devices such as fuel cell technology and converters of methane to higher value-added products such as methanol. It is also intended to develop Anion Exchange Ionomers (AEIs) that will be used as polymeric binders in the electrodes of those electrochemical reactors. AEMs are the main component of electrochemical systems operating in alkaline environment. These membranes have numerous advantages, such as significantly lower cost compared to state-of-the-art acid membrane (Nafion®), less corrosive environment and significantly lower crossover of fuels from the anode to the cathode. However, the main reason why AEMs and AEIs are not yet highly disseminated is the low chemical stability of the functional groups attached to the polymer backbone against the attack of hydroxide ions (OH-), specifically in low hydration media. Among the parameters that affect the preparation of radiation-grafted AEMs and AEIs are those directly related to the radiation source (nature of irradiation, dose rate and dose) and others related to inherent components of the grafting reaction, such as nature of monomer, nature of polymeric film, concentration of monomers, addition of diluents, addition of crosslinking agents, temperature of reaction, addition of inhibitor and film thickness; besides the chemical structure of the amine used in the functionalization reaction. In this context, to obtain more stable materials with specific properties, such as high Ion Exchange Capacities (IEC), this study aims to vary the above parameters in order to obtain unprecedented AEMs and AEIs with subsequent application in electrochemical devices of interest. (AU)