THE CO- A COMBINED STUDY USING SINGLE-CRYSTAL, PLANAR-MODEL-SUPPORTED, AND HIGH-SURFACE-AREA PD(NO REACTION OVER PD )AL2O3 CATALYSTS/

A kinetics study of the CO + NO reaction over Pd has been carried out using single-crystal, model planar-supported, and conventional high-su rface-area Pd/Al2O3 catalysts. A pronounced structure sensitivity is e vident that results in a rate enhancement over the Pd(111) single crys tal relative to the more open (100) and (110) faces, and for larger su pported particles relative to smaller ones. Temperature-programmed des orption (TPD) and X-ray photoelectron spectroscopy (XPS) data indicate that the Pd(100) face is more active for NO dissociation and atomic N stabilization than the close-packed (111) plane. Similarly, TPD resul ts show that smaller particles in the model supported catalysts are mo re active for atomic N formation and stabilization. The inverse correl ation between reaction activity and N, formation and stabilization sug gests that an inactive atomic N species plays a role in determining th e reaction rate. (C) 1997 Academic Press.