Hybrid ceramic nanosieves: stabilizing nanopores with organic links

Abstract

Unprecedented hydrothermal stability in functional membranes has been obtained with hybrid organic-inorganic nanoporous materials, enabling long-term application in energy-efficient molecular separation, including dehydration up to at least 150 degrees C.

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

“…The present article presents a concise overview of the main developments and state of the art in hybrid organosilica membranes for molecular separations since their first report in 2008 [7], with some emphasis on the work done in our group at the University of Twente, in collaboration with the University of Amsterdam and the Energy Center of the Netherlands (ECN). The discussion is limited to ''hybrid'' organosilica membranes, i.e., 3D bonded networks containing :Si-O-Si: and :Si-RSi: groups with homogeneous dispersion of both types of bonds on the atomic scale.…”

“…Some improvement of stability was achieved, but still insufficient for use in industrial processes where water (vapor) is always present. Only the introduction of hydrolytically stable :Si-C 2 H 4 -Si: bonds in the network structure in 2008 resulted in a microporous silica-based membrane with good membrane separation properties for the removal of water from n-butanol, with long-term stability at the industrially relevant temperature of 150°C [7], see Fig. 1.…”

“…Reproduced from Ref. [7] with permission from The Royal Society of Chemistry Fig. 2 Sol-gel precursors-1: bridged silsesquioxane precursor with bridging R group; 2: silsesquioxane precursor with terminal R' group; 3: N,N,N 0 ,N 0 -tetrakis-(3-(triethoxysilyl)-propyl)-malonamide like p-phenylene (-p-C 6 H 4 -) or di-p-phenylene (-p-C 6 H 4 -p-C 6 H 4 -).…”

“…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.…”

Preparation of particulate/polymeric sol–gel derived microporous silica membranes and determination of their gas permeation properties

“…14. The thermal stability of pore network up to 250 • C might be provided by the organically bounded species that suppress the stress induced cracking on membrane surface by increasing toughness of film [24]. The removal of organic moieties might result in increase in permeance values by either formation of large pores or microcracks on surfaces.…”