Poison Effects on Alkaline CO2 Electrolyzer Using Sustainion® Membrane

Abstract

Sustainion® anion exchange membranes have shown superior performance among competition in water and carbon dioxide (CO2) electrolysis. For example, CO2 electrolyzer using Sustainion membrane demonstrated a current density of 600mA/cm2 and a lifetime of over 4000hrs with over 95% CO Faradaic efficiency [1]. The results are achieved with pure CO2. In industrial applications, CO2 feedstocks could be low to mid concentrations CO2 streams from a carbon capture unit or high concentration CO2 streams from biorefinery. CO2 feedstocks from industry often contains impurities such as O2, NOx, SOx, VOCs (volatile organic compounds), and VSCs (volatile sulfur compounds), etc. Some of these impurities could poison the catalysts and degrade the membranes, leading to the early failure of the electrolyzer. In this work we investigated the effects of CO2 concentration and several compounds on the performance of Dioxide Materials electrolyzers for the conversion of CO2 into CO.The results show that most VOCs have no effect on performance. However, acetaldehyde crosses through the membrane and leads to anode degradtation. H2S starts to have significant effect at the 15ppm level. We will present these results and discuss the potential mitigation and/or regeneration strategies. Liu, Z.; Yang, H.; Kutz, R.; Masel, R. I., CO2 Electrolysis to CO and O2 at High Selectivity, Stability and Efficiency Using Sustainion Membranes. Journal of The Electrochemical Society 2018, 165, (15), J3371-J3377.