The aim of this critical review is to provide a broad but digestible overview of mechanochemical synthesis, i.e. reactions conducted by grinding solid reactants together with no or minimal solvent. Although mechanochemistry has historically been a sideline approach to synthesis it may soon move into the mainstream because it is increasingly apparent that it can be practical, and even advantageous, and because of the opportunities it provides for developing more sustainable methods. Concentrating on recent advances, this article covers industrial aspects, inorganic materials, organic synthesis, cocrystallisation, pharmaceutical aspects, metal complexes (including metal–organic frameworks), supramolecular aspects and characterization methods. The historical development, mechanistic aspects, limitations and opportunities are also discussed (314 references).

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Mechanochemistry: opportunities for new and cleaner synthesis

Conversion of Biomass into Chemicals over Metal Catalysts

A.L.-P. thanks CSIC for a contract under the JAE-doctor
program. Financial support by PLE2009 project from MCIINN
and Consolider-Ingenio 2010 (proyecto MULTICAT) are also
acknowledged.

Gold-catalyzed carbon-heteroatom bond-forming reactions.

A study of particle size effects during the catalytic CO2 electroreduction on size-controlled Cu nanoparticles (NPs) is presented. Cu NP catalysts in the 2–15 nm mean size range were prepared, and their catalytic activity and selectivity during CO2 electroreduction were analyzed and compared to a bulk Cu electrode. A dramatic increase in the catalytic activity and selectivity for H2 and CO was observed with decreasing Cu particle size, in particular, for NPs below 5 nm. Hydrocarbon (methane and ethylene) selectivity was increasingly suppressed for nanoscale Cu surfaces. The size dependence of the surface atomic coordination of model spherical Cu particles was used to rationalize the experimental results. Changes in the population of low-coordinated surface sites and their stronger chemisorption were linked to surging H2 and CO selectivities, higher catalytic activity, and smaller hydrocarbon selectivity. The presented activity–selectivity–size relations provide novel insights in the CO2 electroreduction r...

Particle Size Effects in the Catalytic Electroreduction of CO2 on Cu Nanoparticles

Bimetallic Au–Pd nanoparticles (NPs) were successfully immobilized in the metal–organic frameworks (MOFs) MIL-101 and ethylenediamine (ED)-grafted MIL-101 (ED-MIL-101) using a simple liquid impregnation method. The resulting composites, Au–Pd/MIL-101 and Au–Pd/ED-MIL-101, represent the first highly active MOF-immobilized metal catalysts for the complete conversion of formic acid to high-quality hydrogen at a convenient temperature for chemical hydrogen storage. Au–Pd NPs with strong bimetallic synergistic effects have a much higher catalytic activity and a higher tolerance with respect to CO poisoning than monometallic Au and Pd counterparts.

Synergistic Catalysis of Metal–Organic Framework-Immobilized Au–Pd Nanoparticles in Dehydrogenation of Formic Acid for Chemical Hydrogen Storage

Influence of the Support and the Size of Gold Clusters on Catalytic Activity for Glucose Oxidation

Direct deposition of gold nanoparticles onto polymer beads and glucose oxidation with H2O2.

Carbon materials such as activated carbon and carbon black have long been used as adsorbents, electrodes, and supports for metal catalysts. However, no attempt has yet been reported to deposit Au as small nanoparticles (NPs) on these carbon materials directly from Au precursor compounds. Until now, the most effective way to support Au NPs on activated carbon was to physically mix a carbon support with Au colloids prepared beforehand. Here we report that Au could be deposited as NPs on carbon materials directly from gold precursor compounds by deposition reduction method and by solid grinding method. In particular, the solid grinding of carbons with dimethyl Au(III) acetylacetonate, which has a certain degree of vapor pressure at room temperature, is a simple technique but surprisingly effective to deposit Au NPs with a mean diameter as small as 1.9 nm. These highly dispersed Au NPs on carbon supports were tested for glucose oxidation in water with molecular oxygen. A Au/nanoporous carbon (NPC) catalyst which exhibited relatively high catalytic activity has been kinetically studied for comparison with Au/metal oxides catalysts.

Deposition of gold nanoparticles on carbons for aerobic glucose oxidation

PROBLEM TO BE SOLVED: To provide a method for easily depositing a nano-ordered gold fine particle or gold cluster on a carrier in a short time regardless of the material of the carrier. SOLUTION: A sublimable gold precursor (a dimethyl-gold-acetylacetonate complex, a dimethyl-gold-trifluoroacetylacetonate complex, a chlorotrimethylphosphine-gold complex, a methyl(trimethylphosphine)-gold complex or the like) and the inorganic or organic carrier (a polymer, an inorganic oxide, activated carbon, a porous metal complex or the like) are mixed in a solid phase at room temperature under normal pressure while imparting mechanical friction to them and then the obtained mixture is deoxidized so that the gold fine particle is dispersed and fixed to the surface of the carrier. The obtained gold nanoparticle- or gold cluster-deposited carrier exhibits excellent characteristics when used as an oxidation catalyst for oxidizing glucose into a gluconic acid, or a colorant. COPYRIGHT: (C)2009,JPO&INPIT

Method for dispersing and fixing gold fine particle to carrier, gold fine particle-deposited carrier obtained thereby, catalyst and colorant

PROBLEM TO BE SOLVED: To easily manufacture a carbon material or a polymeric material having a surface in which gold nanoparticles useful as a catalyst or the like, having a small particle diameter, free from aggregation, and having a uniform particle size are dispersed and fixed, by reduction of a gold compound. SOLUTION: A reducing agent is gradually added to a gold compound solution coming into contact with a carbon material, a polymeric material having no high polar functional group on the surface, or an organic-inorganic hybrid material consisting of the polymeric material and an inorganic substance and having a content of the inorganic substance of 50 wt.% or less, thereby dispersing and fixing the gold fine particles on the carbon material or the polymeric material. COPYRIGHT: (C)2010,JPO&INPIT

Naoto Kinoshita

Papers

Influence of the Support and the Size of Gold Clusters on Catalytic Activity for Glucose Oxidation

Direct deposition of gold nanoparticles onto polymer beads and glucose oxidation with H2O2.

Deposition of gold nanoparticles on carbons for aerobic glucose oxidation

Method for dispersing and fixing gold fine particle to carrier, gold fine particle-deposited carrier obtained thereby, catalyst and colorant

Method of dispersing and fixing gold fine particle on carrier, and material obtained by this method