ARGONNE NATIONAL LABORATORY

CHEMISTRY DIVISION MONDAY MORNING SEMINAR SERIES

 

SPEAKER:         Professor Horia Metiu

                             University of California at Santa Barbara

 

TITLE:                 Oxidation catalysis by atomic size centers on oxide surfaces

 

TIME:                  11:00 am

                             (refreshments will be available starting at 10:45 am in front lobby)

 

DATE:                 September 17, 2007    

 

PLACE:               Building 200, Auditorium

 

HOST:                 Stefan Vajda       

 

Abstract:  We use density functional theory to examine whether creating -O-M-O-N-O- centers (M and N are different cation, O is oxygen) on an oxide surface can improve its catalytic activity and/or selectivity for oxidation and oxidative dehydrogenation. Such systems can be created by substitutional doping of an oxide with another cation or by depositing MOx oxide clusters on the surface of the oxide NzOy (x, y, z are integers). The purpose of our exploratory studies is to find what kind of chemistry can take place on such systems and how this chemistry changes as we chose various cations for M and N. We explore several scenarios: 1) The presence of the –O-M-O-N-O- activates the oxygen bridging the cations making it more active in oxidation reactions; 2) Both M and O are activated allowing them to cause dissociative adsorption of molecules (we explored methanol adsorption); 3) The cation M is so under-coordinated that it adsorbs gaseous oxygen and makes it reactive. Our purpose is to explore a large class of compounds and sort them according to their reactivity rather than provide detailed, accurate reaction mechanisms for specific systems.