Preparation of hydrophilic ceramic membranes for a dehydration membrane reactor

Water-selective alumina-silica composite membranes were developed as a dehydration membrane reactor for dimethylether (DME) synthesis from methanol. The membranes were modified on a porous stainless steel support by the sol-gel method accompanied by a suction process. The improved membrane modification process was effective in increasing the vapor permselectivity by removal of defects and pinholes. The optimized composite membrane exhibited a water permeance of 1.14×10−7 mol/m2.s.Pa and a water/methanol selectivity of 8.4 at a permeation temperature of 250°C. The catalytic reaction for DME synthesis from methanol using the membrane was performed at 230°C, and the methanol conversion was compared with that of the conventional fixed-bed reactor. The methanol conversion of the membrane reactor was much higher than that of the conventional fixed-bed reactor. The methanol conversion of the membrane reactor and the conventional fixed-bed reactor was 82.5% and 68.0%, respectively. This improvement of reaction efficiency can last if the water vapor produced in the reaction zone is continuously removed.