Bailey JJ

Brett DJL

Bucheli W

Grima L

Kok MD

Merino RI

Metcalfe IS

Mutch GA

Oliete PB

Papaioannou EI

Sanjuan ML

Shearing PR

Composite molten salt-ceramic membranes are promising devices for high-temperature CO2 separation. Intensive material properties impact on separation performance as do membrane geometry (thickness) and microstructure (pore volume fraction, size, connectivity, and tortuosity factor). Although controlling pore size is considered somewhat routine, achieving pore alignment and connectivity is still challenging. Here we report the production of the first gas separation membrane using a porous ceramic matrix obtained from a directionally-solidified magnesium-stabilised zirconia (MgSZ) – MgO fibrilar eutectic as the membrane support. MgO was removed from the parent material by acid-etching to create a porous matrix with highly aligned pores with diameters of ∼1 μm. X-ray nano-computed tomography of a central portion (∼32,000 μm3) of the support identified ∼21% porosity, with all pores aligned within 10\ub0 and ∼76% percolating along the longest sampled length. Employing the matrix as a support for a carbonate molten salt, a high CO2 permeability of 1.41x10-10 mol m-1.s-1.Pa-1 at 815 \ub0C was achieved, among the highest reported for supported molten-carbonate membranes (typically 10-12 to 10-10 mol m-1.s-1.Pa-1 at similar temperatures). We suggest that the high permeability is attributable to the excellent pore characteristics resulting from directional solidification, namely a dense array of parallel, micron-scale pores connecting the feed and permeate sides of the membrane

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High CO<sub>2</sub> permeability in supported molten-salt membranes with highly dense and aligned pores produced by directional solidification

High CO<sub>2</sub> permeability in supported molten-salt membranes with highly dense and aligned pores produced by directional solidification

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