Structure/activity correlations in CO/NO reactions on Pd: From single crystals to small particles

Conference · Tue Oct 01 04:00:00 EDT 1996

OSTI ID:370777

Vesecky, S M; Rainer, D R; Koranne, M M; Goodman, D W ^[1]

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1. Texas A&M Univ., College Station, TX (United States)

The kinetics of CO oxidation by NO has been studied on single crystal catalysts, on model Pd/Al{sub 2}O{sub 3} (50-100 {Angstrom})/Mo(110) thin film catalysts, and on high area alumina-supported Pd catalysts. Infrared reflection absorption (IRAS) studies of CO + NO coadsorption show that NO is stable up to 600K on Pd(111), whereas NO desorbs at 525K on Pd(100). The higher thermal stability of NO on Pd(111) correlates well with the observed higher selectivity for N{sub 2}O over Pd(111) versus Pd(100). Temperature programmed reaction (TPRS) studies show that atomic nitrogen is stable up to 725K on Pd(100) and Pd(110), whereas N{sub 2} desorbs as N{sub 2} at 600 K on Pd(111). The higher stability of atomic nitrogen on the more open Pd surfaces correlates directly with the higher selectivity of these surfaces for N{sub 2} and their overall lower activities. The latter is a result of poisoning by N{sub a}. On the model alumina-supported Pd catalysts, as the particle size increases, the thermal stability of NO{sub a} as well as the gas phase production of N{sub 2}O increases. Correlations between the chemisorptive properties of NO{sub a} or N{sub a} and the activity/selectivity of the model catalysts will be discussed and related to data for high area alumina-supported Pd catalysts.

• OSTI ID: 370777
• Report Number(s): CONF-960376--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
54 ENVIRONMENTAL SCIENCES
ABSORPTION
AIR POLLUTION CONTROL
ALUMINIUM OXIDES
CARBON MONOXIDE
CATALYSTS
CATALYTIC EFFECTS
COMBUSTION PRODUCTS
CRYSTALS
DESORPTION
GASEOUS WASTES
NITRIC OXIDE
NITROUS OXIDE
OXIDATION
PALLADIUM
PARTICLE SIZE
SURFACE AREA
SURFACE PROPERTIES