Boosting the CO2 permeability in a supported molten-carbonate membrane by tuning the ratio between the ionic and electronic conducting phases

Abstract

High-temperature supported molten-carbonate membranes hold significant promise for selective CO₂ capture and utilization from fossil fuel combustion owing to their structural simplicity and cost-competitive operation as opposed to traditional solvent processes. High CO₂ capture rates, that can be quantitatively represented by the membrane’s permeability, are routinely expected to be dictated by the CO₂ driving force or the composition of the molten phase. Here, however, we demonstrate that in a supported molten-salt membrane fabricated using mixed ionic and electronic conducting oxides as the membrane material, the phase ratio between those phases can also control CO₂ permeability. We demonstrate this by using different ratios of Al-CeO₂ (ionic phase) and Al-ZnO (electronic phase) for the membrane material and operate under fixed CO₂ partial pressure driving force to show that higher ionic:electronic phase ratios lead to higher CO₂ permeabilities.