Microporous silica membranes

Microporous silica membranes have a high potential for gas separation and pervaporation at high temperatures in chemically aggressive environments. Well-prepared silica membranes show high fluxes for small gas molecules such as H2, CO2 and O2 and considerable selectivities for these gases with respect to larger gas molecules such as SF6 and hydrocarbons [1,2]. This offers perspectives on applications such as natural gas purification, molecular air filtration, selective CO2 removal and industrial H2 purification. A specific application for these membranes is the use in high temperature membrane reactors in which silica membranes can be of particular use to remove H2 selectively with high fluxes to acieve conversion enhancement in thermodynamically limited reactions. Examples of such reactions can be found in steam reforming, the water-gas shift process, dehydrogenation of hydrocarbons and coal gasification [3,4].