Hydrotalcite material was incorporated to enhance the carbon dioxide (CO2) affinity of the alumina membrane for CO2 separation from different gas mixtures. The crack free mesoporous HT-alumina (-10 urn) porous membranes were successfully synthesized on surface of a-Al203 disc support using the sol-gel and dip-coating techniques. The unsupported membranes were characterized for the presence of HT, surface functional groups, surface topography and morphology, pore size and CO2 adsorption capacity. These characterizations were done using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectrometry, scanning electron microscopy (SEM), Brunauer-Emmett-Teller method (BET) and Thermo gravimetric analyser (TGA) techniques. The modification of alumina membrane with HT enhanced CO2 separation performance. The CO2 permeance was higher than that of methane and nitrogen. While the permeance of hydrogen was almost same to that of CO2 even though the hydrogen molecule was smaller than the CO2 molecule. Indicating that the gas transport through the membrane was predominantly surface adsorption. The mesoporous Hydrotalcite-alumina membrane overcame the Knudsen limitation and produced the highest permselectivity of 2.16 for CO2/CH4 system at 30°C temperature and 100 kPa pressure difference.
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