Dendritic silver self-assembly in molten-carbonate membranes for efficient carbon dioxide capture

Membranes for CO(2)capture should offer high permeant fluxes to keep membrane surface area small and material requirements low. Ag-supported, dual-phase, molten-carbonate membranes routinely demonstrate the highest CO(2)fluxes in this class of membrane. However, using Ag as a support incurs high cost. Here, the non-equilibrium conditions of permeation were exploited to stimulate the self-assembly of a percolating, dendritic network of Ag from the molten carbonate. Multiple membrane support geometries and Ag incorporation methods were employed, demonstrating the generality of the approach, while X-ray micro-computed tomography confirmed that CO(2)and O(2)permeation stimulated self-assembly. We report the highest flux of Ag-supported molten-salt membranes to date (1.25 ml min(-1)cm(-2)at 650 degrees C) and ultrahigh permeability (9.4 x 10(-11)mol m(-1)s(-1)Pa(-1)), surpassing the permeability requirement for economically-competitive post-combustion CO(2)capture, all whilst reducing the membrane-volume-normalised demand for Ag by one order of magnitude.