Nano-Structured Porous Yttria-Stabilized Zirconia Membrane for High-Temperature $${{\rm {CO}}_{2}}$$ CO 2 Capture from $${{\rm{H}}_{2}/{\rm {CO}}_{2}}$$ H 2 / CO 2 Mixture

Abstract

A yttria-stabilized zirconia (YSZ, 8 mol % $${{Y}_{2} {O}_{3}}$$ ) membrane was prepared employing zirconium n-propoxide as a precursor via sol–gel method. Unlike conventional methods, hydrolyzing water was slowly released in this method through esterification of 1-propanol and glacial acetic acid. X-ray diffraction verified that YSZ membrane was partially transformed to the tetragonal phase. Ten times dip-coated membrane thickness was about 742 nm, determined by field emission scanning electron microscopy (FE-SEM) micrograph. Brunauer–Emmet–Teller measured average pore size of unsupported YSZ from gas adsorption and desorption indicating two modes centered at 2.66 and 2.38 nm. Crystallite size (D) as calculated from Scherrer’s equation was 6.8, 12.23, and 13.61 nm for unsupported YSZ powder before and after calcination, respectively, at 25, 500, and $${600\,^{\circ} {C}}$$ . Thermogravimetric analysis showed that the mass loss of the samples calcined at temperatures higher than $${600\,^{\circ} {C}}$$ had no significant differences indicating the completion of loss of organics. Supported YSZ membrane was tested by a gas permeation apparatus. The single gas permeance of YSZ membrane including $${\alpha-{Al}_{2} {O}_{3}}$$ was measured as $${14.89\times10^{-6}}$$ and $${1.75\times10^{-6} \,{ mol m}^{-2} { s}^{-1} { Pa}^{-1}}$$ for $${{\rm{H}}_{2}}$$ and $${{\rm {CO}}_{2}}$$ at $${300\,^{\circ} {C}}$$ , respectively. Permeance of $${{\rm{H}}_{2}}$$ and $${{\rm {CO}}_{2}}$$ through YSZ in 75:25 $${{\rm{H}}_{2}}$$ / $${{\rm {CO}}_{2}}$$ binary feed mixture was $${9.696\times10^{-6}}$$ and $${0.97\times10^{-6} \,{ mol\,m}^{-2} { s}^{-1} \,{ Pa}^{-1}}$$ , respectively, at $${300\,^{\circ} {C}}$$ . The selectivity of hydrogen in YSZ was 10. It was concluded that the membrane was highly promising for the separation of $${{\rm{H}}_{2}/{\rm {CO}}_{2}}$$ mixture from various $${{\rm{H}}_{2}}$$ -containing process streams under steam environment for high-temperature separation.