Seminar Title: Essential Problems Remained in Heterogeneous Catalysis- Formation of new material on the surface

Prof. Ken-ichi Tanaka （Emeritus Professor of the University of Tokyo） 

- Formation of new material on the surface -

Ken-ichi Tanaka

Emeritus Professor of the University of Tokyo

Performance of practical catalysts are quite complex so that people usually explain only apparent correlation between the activity and/or the selectivity observed on the average vales attained by characterization using TEM, EXAFS, NEXAFS et al. We have to consider more seriously the essential problems in catalysis including reaction mechanism.

We look back to a pioneering work on ammonia synthesis reaction on Fe single crystals at high pressure and methanation reaction on Ni, these are structure insensitive catalysis.  We have to consider either the structure or the material formed on the surface is responsible for the structure insensitive phenomena. I wish to emphasize the importance of the formation of materials.  The origin of the complexity of practical catalyst is caused by the formation of functional materials in the preparation of catalyst, that is, the reaction of supported metal with promoting materials and/or support materials, and the formation of active materials by pretreatment and/or during reaction. I will show you an interesting model of catalysis by forming a new functional compound by using Pt, Rh, and Pt/Rh bimetallic surfaces.

Based on the idea of the formation of new materials, I wish to emphasize the importance of reaction mechanism in catalysis.  I wish to focus on the oxidation reaction of CO, which is not so simple when H₂O or H₂ is coexist on certain catalyst.  We have to consider the hydro-oxidation in the PROX reaction of CO.  I wish to discuss superior activity of Pt in SiO₂-nanotubes, extremely high activity of Pt/carbon nanotubes, FeO_x loaded Au/TiO₂, in relation to interesting activation of Au particles on Au/CeO₂ depending on morphology of CeO₂observed by the group of Xiamen university.