AVS 49th International Symposium
    Surface Science Monday Sessions
       Session SS1-MoA

Paper SS1-MoA4
In situ Monitoring of the Catalytic CO + NO Reaction on Pd(111) at 240 mbar: The Formation of Isocyanate

Monday, November 4, 2002, 3:00 pm, Room C-108

Session: Surface Reactions: CO and NO
Presenter: Ch. Hess, Texas A&M University
Authors: Ch. Hess, Texas A&M University
E. Ozenzoy, Texas A&M University
D.W. Goodman, Texas A&M University
Correspondent: Click to Email
The CO + NO reaction to form CO@sub 2@, N@sub 2@O and N@sub 2@ has been studied on a Pd(111) surface at pressures up to 240 mbar by using in situ polarization modulation infrared reflection absorption spectroscopy (PM-IRAS). At a pressure ratio of P@sub CO@/P@sub NO@ = 1.5 and temperatures above 500 K, i.e., under reaction conditions, besides CO and NO, isocyanate is adsorbed on the surface as evidenced by isotope experiments. Below 0.1 mbar total pressure, however, no isocyanate formation was observed. The role of the isocyanate in the CO + NO on Pd(111) is discussed by comparison of the spectroscopic and kinetic results. In addition, kinetic measurements of the CO + NO reaction between 590 and 650 K showed an increase in the N@sub 2@O selectivity, a result of temperature-dependent changes of the ratio [NO]@sub a@/[CO]@sub a@. Within this temperature range, the apparent activation energy of the reaction was determined to be 54 ± 21 kJ/mol.