Development of an all-ceramic module with silica membrane tubes for high temperature hydrogen separation

Heat resistant hydrogen selective membranes are desired for use as membrane reactors in low-temperature hydrogen production via the steam reforming of hydrocarbons, which are usually operated over 1000K. In addition, developing a multi-tubular type of membrane unit that can process more reactants is becoming more and more important in order to realize the practical use of membrane reactors. In this study, an all-ceramic module consisting of 6 silica membrane tubes with a comparatively large membrane area of around 0.04m2 was fabricated by a counter-diffusion chemical vapor deposition technique. As a result, the H2/N2 ideal separation factor and the H2 permeance of the module were 1300 and 1.910-7molm-2s-1Pa-1 at 873K, respectively. In a 1000-hour thermal stability test for the silica membrane module, it was found that the H2 permeance initially decreased by about 30% and then became steady under P=0.95MPa at 773K.