Hydrothermally stable molecular separation membranes from organically linked silica

Structure–property tuning in hydrothermally stable sol–gel-processed hybrid organosilica molecular sieving membranes

“…solvation shell) of 2.2 nm as determined by dynamic light scattering (DLS) were reported to penetrate extensively into the underlying c-Al 2 O 3 substrate layer with 6-nm-wide pores upon dipcoating. Comparable sols with an average size of 4.9 nm yielded defect-free membranes [19], but sols with an average hydrodynamic diameter of 13 nm formed thick films with visible macroscopic cracks after drying. High-throughput screening approaches have been employed to optimize the colloid size of various bridged precursors with methylene, ethylene, p-phenylene and di-p-phenylene bridging groups [28].…”

“…Hence, mixing of TEOS, MTES and BTESE precursors leads to a substantial degree of co-condensation of dissimilar precursor types. In this way, the degree of condensation of BTESE into inert dimeric species can be minimized [19].…”

“…In early studies on hybrid organosilica membranes based on BTESE, it was attempted to avoid the formation of condensed bicyclic carbosiloxanes [7,19]. Such oligomers have been reported to slow down or even inhibit gelation and may not become incorporated in a continuous network structure [22,23].…”

“…The microporous layer is 20-300 nm thick. The mesoporous substrate on which this layer rests consists of a c-Al 2 O 3 [7,19,20], anatase [21] or other mesoporous layer and has pore sizes of 3-10 nm. Since permselective silica membranes are very resistive to molecular transport, its thickness should be kept as low as possible to maximize the flux under a given concentration gradient.…”

High-temperature steam reforming of methanol over ZnO–Al2O3 catalysts

“…The specific surface areas (S BET ) of the samples were measured by the BET method on an AutoChem 2910 instrument using nitrogen adsorption isotherms at 77 K (the cross section of the nitrogen molecule was taken to the 0.162 nm 2 [35]). …”