Preparation and Hydrothermal Stability of Organic-inorganic Hybrid Silica Membrane

A new organic-inorganic hybrid microporous membrane was prepared via Sol-Gel method with bridged silsesquioxane(1,2-bis(triethoxysilyl)ethane,BTESE) as a precursor.Macroporous α-Al2O3 disk supported mesopo-rous γ-Al2O3 layer was used as support.Defect-free hybrid silica membrane was deposited on such support by using a stable nano-sized sol and subsequently calcining in pure nitrogen atmosphere.The hybrid SiO2 membrane as well as the powder was characterized by TG/DSC,BET and gas permeation.The hybrid silica membranes exhibit molecular sieve properties for small gases like He,CO2,O2,N2,CH4,and SF6 with helium permeance in the range of(1.0-3.5)×10-7mol/(m2·s·Pa)(at 200℃,0.3MPa).Considering the membrane calcined at 500℃,it is found that the permselectivity of the He(0.255nm) with respect to CO2(0.33nm) is 47,which is much higher than the corresponding Knudsen value(He/CO2=3.3).Effect of calcination temperature on hydrothermal stability of those microporous membranes was studied in detail.Results show that the performances of hybrid SiO2 membranes calcined at 450℃,500℃ and 550℃ deteriorate under a H2O partial pressure of 200,500 and 1000kPa,respectively.