New Research


Metal Nanoparticle Catalyst

Development of newly designed metal nanoparticle catalysts for environmentally-benign chemical proce

Prof. Koichiro JITSUKAWA, Assoc.Prof. Tomoo MIZUGAKI, Assist.Prof. Takato MITSUDOME

   "Catalyst" is essential for conversion of materials and energy. It makes our daily necessaries, and moreover, it exists in our body. For construction of environmentally-benign chemical processes, we are preparing high-performance catalysts according to the concert effect between metal nanoparticles and supports. Under our design concept that is simple and clean reactions, organic and inorganic crystals acting as macroligands are used to immobilize and stabilize metal species, such as mono- and multi-nuclear metal complexes and metal nanoparticles.

   For example, we have found that the palladium(Pd) cluster, of which size is less than 1nm, is stabilized in the dendrimer as an organic macroligand, and the catalytic activity increases with increasing the particle size. This finding is opposite to the previous reports using the conventional Pd nanaoparticle catalysts. In addition, silver(Ag) nanopaarticle, which has been known as less active metal, shows high catalytic performance for oxidation of alcohols and hydration of nitriles when it is immobilized on the surface of the inorganic crystal. Furthermore, gold(Au) and copper(Cu) nanoparticles are highly active for synthesis of lactones from diols under mild conditions. These solid catalysts here prepared are easily recovered from the reaction solution and reused without any loss of the catalytic activities.

   Now, we are developing the novel ”core-shell” type nano composite catalyst, in which Ag nanoparticle is wrapped by the assemblies of seria nanoparticle (Figure). This catalyst can reduce nitro and epoxy groups into the corresponding amino and alkene ones without hydrogenation of C=C double bond. It attracts much attention as a new generation catalyst with demonstrating the high-performances to convert only a specific functional group with high selectively.

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