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

McNeil, Liam A. and Mutch, Greg A. and Iacoviello, Francesco and Bailey, Josh J. and Triantafyllou, Georgios and Neagu, Dragos and Miller, Thomas S. and Papaioannou, Evangelos I. and Hu, Wenting and Brett, Dan J. L. and Shearing, Paul R. and Metcalfe, Ian S. (2020) Dendritic silver self-assembly in molten-carbonate membranes for efficient carbon dioxide capture. Energy & Environmental Science, 13 (6). pp. 1766-1775. ISSN 1754-5692

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    Abstract

    Membranes for CO2 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 CO2 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 CO2 and O2 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 °C) and ultrahigh permeability (9.4 × 10−11 mol m−1 s−1 Pa−1), surpassing the permeability requirement for economically-competitive post-combustion CO2 capture, all whilst reducing the membrane-volume-normalised demand for Ag by one order of magnitude.