A vibrational spectroscopic study of the CO + NO reaction: From Pd single crystals at ultrahigh vacuum to Pd clusters supported on SiO2 thin films at elevated pressures

COLL 342

D. Wayne Goodman, Emrah Ozensoy, and Christian Hess. Department of Chemistry, Texas A&M University, P. O. Box 30012, College Station, TX 77842-3012
The catalytic reaction between CO and NO has been studied on two different model catalysts using polarization-modulation infrared reflection absorption spectroscopy (PM-IRAS) technique within a wide pressure regime (10-6 - 240 mbar). On the atomically flat Pd(111) surface, besides the behavior of the adsorbed reactant species, formation of an isocyanate (-NCO) species was followed under high pressure conditions. The relationship between the –NCO formation and the total pressure of the reactants as well as the CO/NO partial pressure ratio was examined. The reaction kinetics was also investigated by gas phase infrared spectroscopy. The Pd (111) single crystal studies have been extended to a more complex and realistic model catalyst prepared by depositing Pd clusters onto a crystalline SiO2 thin film grown on an atomically clean Mo(112) substrate.