Alumina separation layer with uniform pore size applied on a support with broad pore size distribution

Coal fly ash (CFA) is a promising substitute material in ceramic membrane fabrication to address the high membrane cost issue. However, supports prepared with CFA usually have wide pore size distributions, leading to difficulties in fabricating separation layers. This study focused on overcoming the selectivity-permeability trade-off of membranes based on the CFA support. Five different sizes of alumina powders were adopted to optimize the particle size for separation layer preparation. The membrane prepared using the powder with mean particle size of 1.11 μm under 1150 °C sintering had the best comprehensive performance. The mean pore size was 161 nm and the permeability was 879.71 L/(m2∙h∙bar). Membranes with smaller coating particles had defects because of the particle penetration while membranes with larger particles showed little pore size difference with the support. This work offers opportunities to broaden the application of low-cost CFA membranes.