Successive Use of Amphiphilic Block Copolymers as Nanoreactors and Templates:  Preparation of Porous Silica with Metal Nanoparticles

Abstract

A new way for preparation of microporous silica containing metal nanoparticles inside pores is described. Special amphiphilic block copolymers, polybutadiene-b-poly(ethylene oxides), are used in a first step as nanoreactors for the preparation of metal nanoparticles inside their micelle cores and then as templates where the micelles act as porogens. The final product after calcination of the polymer is silica where catalytically interesting nanoparticles with controlled size, shape, and distribution are located on the pore walls. Control for nanoparticle growth and location is provided by the reduction conditions.

Pd/SiO2 catalysts: synthesis of Pd nanoparticles with the controlled size in mesoporous silicas

“…Work has been directed toward the synthesis of nanoparticles (nanowires) of the metals, such as palladium [20][21][22][23][24][25][26][27][28][29][30][31][32][33], platinum [8,20,[34][35][36][37][38][39][40], ruthenium [41][42][43][44][45][46][47], gold [48][49][50][51], silver [36,52], within the channels of mesoporous silicates, mainly, MCM-41. The metals were introduced into the support either directly during the mesoporous silicate synthesis, or by post-synthesis treatment.…”

“…The metals were introduced into the support either directly during the mesoporous silicate synthesis, or by post-synthesis treatment. Direct incorporation was performed adding the metal precursor into the synthesis silica gel before ageing [34,37,45] or by a stabilisation of the metal precursor inside the template micelles during the self-assembly of the surfactant and silicate [30,32,47]. The post-synthesis metal deposition was carried out using a calcined mesoporous support via incipient wetness impregnation [35,39], ion-exchange [25][26][27]53], equilibrium adsorption, metal complex immobilisation [8,22], and vapour-phase grafting [23,31].…”

Nanostructured Polymeric Nanoreactors for Metal Nanoparticle Formation

“…However, when water is concerned as a solvent, there are very few suitable block copolymers-that is, those forming micelles in water and containing functional groups in the micelle core. A few examples of such block copolymers include PEO-b-P2VP and PEO-b-PB [40,41]; the micellization of the former block copolymer depends on pH [42]. At pH below 5, PFO-b-P2VP becomes molecularly soluble in water.…”

H2S Removal Using ZnO/SBA-3: New Synthesis Route and Optimization of Process Parameters

“…In the former case, the most usual method is doping of reaction m elange with metal salts [15]. In post-synthetic approach, the most common synthesis routes are: I) incipient wetness impregnation [16]; II) ion exchange [17]; III) equilibrium adsorption [18]; IV) metal complex immobilization [19]; V) vapor phase deposition [20]; and VI) sonication [21][22][23][24].…”