News from Nanotechjapan


Highly-Active Aerobic-Oxidation Catalyst Realized by Subnano-Sized Particles---Metallic nano-particles light up another path towards eco-friendly catalysts---

 Tokyo Institute of Technology announced on 16 Nov. 2018 that the research team led by Prof. Kimihisa Yamamoto at the Institute of Innovative Research produced subnano-sized metallic particles that are very effective as catalysts for the oxidation of hydrocarbons. The results were published in Angewandte Chemie International Edition*.

 Although the oxidation of aromatic hydrocarbons is important for producing useful organic compounds, most of the conventional processes require environmentally hazardous catalysts and solvents. Thus, a solvent-free oxidation process using nano-sized catalytic particles has attracted considerable attention. In this study, the team synthesized subnanocatalysts (SNCs) containing various noble metals (Cu, Ru, Rh, Pd, or Pt) using dendrimer (dendritic polyphenylazomethine) as a macromolecular template, which are tree-like spherical molecules to provide internal nanospaces for metal particles. Each dendrimer molecule hosts a subnano-sized metallic particle that catalyzes the oxidation of aromatic hydrocarbons, such as toluene, to produce benzoic acid without solvents. Various catalysts of different sizes and metal species were prepared to test their catalytic activity. Smaller SNCs were found to show better activity, while Pt, that is less oxophilic and does not oxidize easily, was superior. Pt clusters consisting 19 atoms (Pt19 SNC) showed the highest catalytic performance, which is 50 times higher than the common Au-Pd nanocatalysts.

 The team suggests that applications of such catalysts could greatly contribute for reducing pollution and enhancing our effective use of Earth's metal resources.
*Miftakhul Huda, Keigo Minamisawa, Takamasa Tsukamoto, Makoto Tanabe, and Kimihisa Yamamoto, "Aerobic Toluene Oxidation Catalyzed by Subnano Metal Particles", Angewandte Chemie International Edition, Accepted Articles, DOI: 10.1002/anie.201809530; published: 14 November 2018