コロイド状および担持ナノ粒子の設計─その合成，構造解析と触媒作用─

Abstract

Fabrication of nanoparticle (NP)-based materials have attracted much attention in the field of catalysis, because their special properties lie between those of single metal species and bulks. In this review article, we highlight our recent progress in the development of promising NPs-based catalysts designed by precise architecture that enable efficient and selective chemical reactions and can be easily separated and recyclable. Firstly, novel strategies to fabricate well-controlled catalytically active metal NPs on solid supports are described. A single-site photo catalyst comprising tetrahedrally coordinated Ti-oxide moieties within a silica framework (Ti-MCM-41) enabled a high dispersion of metal NPs via the photo-excitation. Both the deposition of Pd and Au to form PdAu bimetallic NPs was also accomplished under UV-light irradiation. These bimetallic NPs showed an improvement in the catalytic efficiency of H2O2 formation. Based on pH-induced assembly-dispersion properties of Ag NPs stabilized with 3-mercaptopropionic acid (3-MPA), the deposition of Ag NPs on Al2O3 support was successfully attained by electrostatic attraction while keeping their inherent dispersion state. In the second topic, new multifunctional nanocomposites exhibiting magnetic properties and catalytic activities are presented. Magnetic NPs were encapsulated with silica layer containing isolated and tetrahedrally-coordinated Ti-oxide species, which offered simple and efficient catalyst systems for the selective liquid-phase oxidations. The FecorePtshell NPs stabilized by oleic acid and oleylamine was drastically improved by the formation of an inclusion complex with γ-cyclodextrin (γ-CD), which showed an enhanced catalytic activity in water rather than in organic solvents. Similarly, the FecorePdshell NPs were subsequently treated with 2,2'-bis(diphenylphosphino)-1,1'-binaphthene (BINAP) as chiral modifiers, which were shown to catalyze the asymmetric Suzuki-Miyaura coupling reaction. Hollow γ-Fe2O3 nanoshperes with diameter of 400-500 nm have been synthesized by a simple templating method combined with subsequent thermal treatments and calcinations. It exhibited higher catalytic activity than its bulk counterparts and also showed a satisfactory selectivity compared to the nano-γ-Fe2O3. The synthetic strategies described here are simple and general for practical catalyst design; thus allowing a strong protocol for creating various nanostructured catalysts.

Curing Behavior of Waterborne Paint Containing Catalyst Encapsulated in Micelle

“…For instance, Wang et al reported smart supramolecular nano-enzymes with temperature-driven switching properties have been successfully constructed by the self-assembly of supra-amphiphiles formed by the cyclodextrin-based host-guest chemistry [9]. Although reviews have also examined the application of this approach in various industrial fields [17][18][19][20][21], no reports have examined its applicability to automotive paints. However, since cyclodextrin, which tends to be used for these inclusion compounds, has high hydrophilicity, it is presumed that the compounds described in these reports would not satisfy the high-performance requirements of automotive paint films.…”

Synthesis of a Fe–Ni Alloy on a Ceria Support as a Noble‐Metal‐Free Catalyst for Hydrogen Production from Chemical Hydrogen Storage Materials

“…To overcome these drawbacks, small NPs have generally been used on suitable supports, such as polymers, metal oxides, mesostructured materials, and carbon materials, which also provide unique catalytic functions including site isolation of active metal NPs, cooperative action by several sites, and synergic effects owing to the strong metal‐support interactions 9a. 11…”

Recent Advances in the Application of Magnetic Nanoparticles as a Support for Homogeneous Catalysts

“…This will prevent the necessity of additional purification techniques to remove the catalyst from the waste stream making it a “greener” catalyst comparing to previous approaches. This area has deserved a lot of attention and there have been several good reviews on the subject of catalysts immobilised onto magnetic nanoparticles [ 6 , 16 , 25 , 26 , 27 , 28 , 30 ]. The current review considers only the most recent developments in this field during the last few years.…”