Research Subject 1 Development of New Inorganic Membranes Membranes – Ceramic membranes for H 2 separation – Ceramic membranes for CO 2 separation – Studies address mechanism of permeation Prediction of permeation properties

New Silica Membranes Alumina support (Pall Corporation, pore size 100 nm) Si(C 2 H 5 O) 4 (TEOS) SiO 2 membrane (Nanosil) Thermal CVD (873 K) Connected by glass joints Dense alumina tubing Porous support 1 cm

Experimental Equipment for CVD 4 cm CVD condition : 873 K, 1 atm (0.07 mol % of TEOS) Mass Flow Controller ATSB Oil Bath Balance Gas Dilution Gas Furnace Membrane Carrier Gas Vent Oxygen & WaterTrap MFC Vent Temperature Controller TEOS Water Bath MFC Heating Tape

CrackingInfiltration Smaller sol particles Larger sol particles Incomplete coverage Large spaces Graded layers Approach for a Thin, Defect-free Intermediate Layer

Sol Processing & Particle Size Distributions of Sols Lower acidity produces larger particle sizes H + /Al alkoxide Aluminum alkoxide Stirring & heating Acid Water Hydrolysis Peptization Clear Boehmite Sol Refluxing -Al 2 O 3 Layers Calcination Al(OR) 3 + H 2 O Al(OH) 3 -(O-Al-O-Al) x AlOOH colloidal particles

Scanning Electron Microscopy Silica layer Graded substrate Support 1000 nm High resolution SiO 2 layer (L = 20 nm)  - Al 2 O 3 layer 100 nm

Permeability and Selectivity of Nanosil Membranes P = 5 x S > 99.9% Two-layer membrane Three-layer membrane Y. Gu, S. T. Oyama, J. Membr. Sci. 2007, 306, 216.

Comparison to Palladium Pd Membranes

Statistical Model Key parameters: * = vibrational frequency d = jump distance Δ EkEk N s = number of solubility sites Permeation occurs by jumps between adjacent solubility sites TranslationRotationVibration Membrane Permeation equation: S. T. Oyama, D. Lee, P. Hacarlioglu, R. F. Saraf, J. Membr. Sci., 2004, 244, 45. Y. Gu, S. T. Oyama, Adv. Mater. 2007, 19, 1636 P

Structure of Pd-Cu Membrane (5 nm) Low resolution (20 k X) High resolution (100 k X) Pd-Cu Intermediate layer  - alumina support (5 nm pore) Dip coating of one intermediate layer Electroless plating of Pd-Cu

Diffusion Energy Calculation Model: Becke3lyp (DFT) Basis set: 6-311G(2d,p) x y z Normal to the xy plane Saddle Point Diffusion Energy

Activation Energy vs. Distance to O atoms Hydrogen Helium 8-membered 4-membered 5-membered 6-membered 7-membered Glasses Silica layer P. Hacarlioglu, D. Lee, G.V. Gibbs and S.T. Oyama, J. Membr. Sci. 2008, 313,