abstracts - Институт катализа им. Г.К. Борескова

CAN QUANTUM CHEMISTRY HELP TO TAYLOR A CATALYST FORA PARTICULAR REACTION?Witko M.Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences,ul. Niezapominajek 8, 30 239 Cracow, PolandE-mail: ncwitko@cyf-kr.edu.plKS-III-7At present, a main goal of catalytic science is to tailor the most active and selectivecatalyst for a particular reaction. This requires understanding of a mechanism of the reactionand of the catalyst role, which cannot be obtained without a detailed knowledge of its physicaland chemical properties. Such a goal demands synergy between two parallel andcomplementary approaches: experimental and theoretical, and gives the opportunity tomanufacture catalyst for a particular reaction. In the following the role of theory will be willbe illustrated on the example of V-O systems.Vanadia-based catalysts are used in many different processes that belong to various typesof chemical reactions. They catalyze mild (ammo)oxidation, oxidative dehydrogenation,dehydrocondensation, dehydrocyclization and many oxidation processes. Vanadia withmixture of other oxides (Mo-O, Ti-O, Sb-O) is used in a few industrial processes such asoxidation of propene into acrolein and acrylic acid, benzene to maleic anhydride, anthraceneto anthraquinone or propylene to acrylonitrile.A wide application of V 2 O 5 as catalyst follows from a fact that its crystallites may exhibittwo structurally different types of faces: surface built of chemically saturated atoms and thosebuilt of unsaturated cations and anions. Both show different behavior in catalytic reactions byperforming a complex multi-step operation on the reacting molecule through activation ofsome of the bonds within reactant and hindering those interactions, which could result inunwanted product.In the lecture the energetic stability of low-indices (010), (100) and (001)V 2 O 5 surfaceswill be compared based upon periodic DFT calculations. The electronic structure and activityof structurally different surface oxygen sites will be discussed using both cluster and periodicapproaches. Adsorption of hydrogen leading to the formation of surface hydroxyl and waterspecies as well as hydrogen migration through the surfaces will be considered. Creation ofsurface oxygen vacancies will be undertaken and followed by their re-oxidation through thegaseous oxygen.65