Evaluation of the performance of α-alumina nano-porous ceramic composite membrane for esterification applications in petroleum refinery

Abstract

The carrier gas permeation performance through α-alumina nano-porous ceramic membrane was investigated in this study. The four carrier gases used for the study were argon (Ar), helium (He), nitrogen (N2) and carbon dioxide (CO2). The experiments was carried out at the gauge pressure drop of 0.10–1.00bar at 80°C. The α-alumina membrane was prepared using the sol-gel dip-coating techniques. The dip-coated membrane exhibited a higher molar flux with He (0.046molm−2s−1) and Ar (0.037molm−2s−1) with a much lower flux for N2 (0.037molm−2s−1) and CO2 (0.035molm−2s−1) at 0.30bar. The membrane recorded a huge decrease of permeance with the four carrier gases in the range of 9.81783E-07molm−2s−1Pa−1 to 1.23237E-06molm−2s−1Pa−1 at 0.50bar. The gas flow rate increased with respect to the pressure drop across the membrane. A plot of the inverse square root of the gases molecular weight showed a linear dependence on the gas permeance. The order of the gas flow rate with respect to the mean pressure was He>Ar>CO2>N2. The membrane was characterised using different methods including liquid nitrogen physisorption (Quantachrome instrument 2013) and scanning electron microscopy (Zeiss EVO LS10 SEM). The liquid nitrogen adsorption isotherm were described using the BET and BJH methods The BET surface area of the 7th dip-coated membrane was found to be higher (5.991m2/g) in contrast to the 8th dipped (3.840m2/g). The BJH pore size distribution of the membrane show a reduction pore size after the modification process. The BET isotherms of the membrane indicated a type IV isotherm with hysteresis on the curve indicating that the membrane can undergo a capillary condensation in the mesoporous region. The SEM/EDAX of support showed a clear surface without evidence of crack while the SEM micrograph of the silica membrane exhibit a bonding on the surface membrane as result of the modification process.