Computational design of bimetallic nano catalyst and metal oxide catalysts

Abstract

“Trial and Error” the traditional experimental synthesis and subsequent analysis of catalysts has been a widely applied strateagy in designing new heterogeneous catalysts. In this thesis, I use a computational approach, as a substitute of erroneous and time consuming experimental method, to study several interesting and most hot topics in the field of heterogeneous catalyst. Computational approach allows us to separately study a complex reaction pathway and to analyze the effect of a structure, composition, and a dimension of a catalyst. On account of such benefits of computational method, I set an object of this study to “Catalyst activation by designed reaction center.” In Chaper 1, the combined computational method of a molecular dynamics, the modified basin-hopping Monte Carlo simulation, and the Density Functional Theory is applied to study an Ag-Pd bimetallic nano cluster. The temperature dependent structural evolution, the surface catalytic reaction, and the structure dependent catalytic activity of nano clusters are discussed. I show that a small Ag-Pd bimetallic nano cluster can be a robust catalyst for CO oxidation. Solute element acted not only a reaction modifier but also a structural stabilizer. In Chapter 2 and 3, I expand the scope of the study to metal oxide catalysts. In Chapter 2, doped metal oxides are suggested as a new kind of oxidation catalyst. The modified catalytic activity of V, Cr, Mo, W, or Mn doped $TiO_2$ catalyst is tested via CO oxidation. I propose the vacancy formation energy as a reaction descriptor. In Chapter 3, the reaction mechanism of methanol dehydrogenation catalyzed by $TiO_2$ supported VOx, MoOx, and CrOx catalysts is analyzed. The location of the reactive surface oxygen species is studied by a state-of-art Density Functional Theory.