High-performance membrane supports: A colloidal approach to the consolidation of coarse particles

Inorganic membrane supports, for hydrogen separation, must provide adequate surface morphology for the deposition of thin film membranes while offering acceptable permeability and mechanical strength. Supports prepared from stabilized suspensions of Sumitomo AKP30 and AKP15 powder were shown to exhibit ideal surface morphology (average roughness ∼30nm) and excellent mechanical strength (>200MPa), but inadequate permeability, ∼1×10-6mol/m2sPa for H2H2 at STP. The colloidal stabilization, subsequent vacuum filtration and sintering of coarse ∼3μm Ø α-Al2O3α-Al2O3 particles are shown to increase pore size from ∼70nm (AKP30) to ∼700nm (AA3) and consequently improve permeability by ∼10×∼10×. The cost price of these supports can be decreased and sufficient flexural strength achieved with a low temperature phosphate bonding technique. Through the precise control of the colloidal chemistry and consolidation process, the near surface morphology of the supports can be intrinsically graded with ∼0.5μm particles gradually coarsening to ∼3μm. Supports generated in this manner then exhibit a smooth surface morphology comparable to AKP15 supports (average roughness ∼100nm) and mechanical strengths of ∼100MPa.