Grinding solids

Figure 3.8 Schematic representation of solid grinding (SC) method.

Highly active Au catalysts can be prepared by an appropriate selection of preparation methods such as co-precipitation (CP), deposition-precipitation (DP), deposition-reduction (DR) and solid grinding (SG) with dimethyl Au(III) acetylacetonate, depending on the kind of support materials and reactions targeted. 

As with the hydrothermal method, solid-solid grinding reactions, or mechanochemical reactions as they are also called, is a method with long tradition in solid state chemistry that has recently been applied also to molecular chemistry [56,57]. This method has several advantages ... 

Ishida, T, Nagaoka, M., Akita, T, and Haruta, M. Deposition of gold clusters on porous coordination polymers by solid grinding and their catalytic activity in aerobic oxidation of alcohols. Chem-Eur J14, 8456-8460 (2008). 

Deposition of gold clusters onto porous coordination polymers by solid grinding... 

Porous coordination polymers (PCPs), having highly ordered nanometer-sized porous structures, have recently been attracting interests as supports for metal clusters [3]. However, it was difficult to deposit Au as clusters on or in PCPs by conventional chentical vapor deposition (CVD). In this work, we demonstrated the direct deposition of Au as clusters onto PCPs by a solid grinding method and investigated their catalytic performance for one-pot A/-aIkylation of amine with alcohol. 

On the contrary, solid grinding method enabled us to deposit Au NPs in diameters below 5 nm with narrower size distributions as compared to CVD for all the three PCPs (Figure 2 and Table 1). 

Gold clusters smaller than 2 nm in diameter could be deposited onto A1-MIL53 by solid grinding. Gold clusters on Al-MIL-53 enabled A-alkylation of aniline with benzylalcohol to produce the secondary amine in one-pot under N2 atmosphere. The dehydrogenation of alcohol took place over Au clusters on Al-MIL-53 to form Au-H species, which was utilized for the hydrogenation of imine, while it did not over Au NPs on MOF-5 and CPL-2. 

Figure 11.7 Possible pathways for the formation of gold clusters and NPs by solid grinding of dimethyl acetylacetonate Au(lll) ((CH3)2Au(acac)) with alkaline treated TS-1 and TS-1. (Reproduced with permission from Elsevier [62].)...

Recently, we developed a simple method, namely solid grinding, to deposit gold clusters (l-2nm) on alkali-treated TS-1 on which many surface defects were created after KOH (or NaOH) treatment of TS-1. Gold clusters with diameters of 1-2 nm could be stabilized by these surface defects even after reaction at 200 °C for 36 h. These 1-2 nm gold clusters could catalyze the epoxidation of propylene with molecular oxygen if a small amount of water ( 2.0% in volume) was introduced to the feed gas. A PO selectivity of 52% and a C3H5 conversion of 0.88% were achieved [15]. Once water was removed from the feed gas, PO could not be produced again. 

---