Simple preparation of silica and alumina with a hierarchical pore system via the dual-templating method

Abstract

Silica and alumina with macro-meso-type hierarchical pore systems are synthesized by dual templating using both surfactants and polystyrene (PS) spheres. After calcination, scanning electron microscope images show uniform macropores with a diameter of approximately 200 nm. This size coincides with that of the original PS spheres. The density of the macropores increases with the amount of added PS spheres in the precursor solutions. Transmission electron microscope images, small-angle x-ray scattering spectra and N 2 adsorption-desorption isotherms reveal the formation of ordered mesoporous structures in the macropore walls. Also, the existence of micropores (less than 2 nm in size) was confirmed from the large N 2 uptake at low relative pressures.

Macro-porous ceramics: processing and properties

“…During heat treatment of preceramic polymer with silicone network, organic groups can be decomposed and be transferred to inorganic bonds such as Si-O, Si-C and Si-N, and usually under inert atmosphere to prevent an oxidation of organic groups. When preceramic polymer is used as raw material to fabricate hierarchically porous ceramic, meso-or micro-porosity has been formed by varying the pyrolysis temperature of preceramic polymer, 235,236 using the block copolymer, [237][238][239][240][241][242] and the addition of filler into the polymer. 236,243 Several macro-porous processing approaches including sacrificial fugitives, replica templates and direct foaming have been utilised in order to provide the macro-posority.…”

“…Kim et al 238 fabricated hierarchically porous alumina with meso- and macro-pores, where meso-porous structure was obtained using alkyl carboxylate as a chemical template, and macro-pore structure was developed through polystyrene beads or silica gels. Suzuki et al 239 prepared hierarchically porous silica and alumina by dual templating method of surfactant and polystyrene beads. They confirmed macro-pores around 200 nm from the polystyrene sphere, and ordered meso-pores around 4 nm due to the triblock copolymer and micro-pores of <2 nm due to the tail of copolymer.…”

Studies on the improved thermal stability for doped ordered mesoporous γ-alumina

“…Ariga et al 10 introduced many examples of recent developments in nanoarchitectonics for mesoporous materials with innovations in component or structural designs, including mesoporous g-Al 2 O 3 . At the moment, various techniques such as spin-coating, 11 one-step fabrication 12 and dual-templating method 13 are used to obtain mesoporous g-Al 2 O 3 with vertical or hierarchical mesoporosity. The spin-coating technique can be also applied in other systems, for instance mesoporous TiO 2 .…”

Dispersion of Al2O3 nanoparticles stabilized with mussel-inspired amphiphilic copolymers in organic solvents and formation of hierarchical porous films by the breath figure technique

“…The hierarchy of the pores increases the surface area and improves the substance diffusion of the materials. [8][9][10] For example, hierarchical porous titanium oxide shows high photocatalytic activity. 11 Honeycomb-patterned porous polymer films are formed by casting polymer solutions containing a hydrophobic polymer and an amphiphilic copolymer dissolved in water immiscible organic solvents on a solid substrate under humid conditions.…”