CHARACTERIZATION AND CATALYTIC PROPERTIES OF PT-IR SMALL BIMETALLIC CLUSTER IN NAY

Abstract

The formation of small Pt-Ir bimetallic clusters (about 1 nm) by the reducton of Pt and Ir co-ion-exchanged NaY with H-2 at 300-degrees-C after calcined with oxygen at 300-degrees-C was evidenced by temperature programmed oxidation/reduction (TPO/R), Xe-129 NMR, hydrogen chemisorption and catalytic probe reaction. These small Pt-Ir bimetallic clusters inside the supercage were more stable than Ir monometallic cluster and remained inside the supercage after re-oxidation treatment below 400-degrees-C. Temperature programmed oxidation/reduction (TPO/R) results suggested that the interaction between Pt and Ir takes place in the calcination step prior to hydrogen reduction. The Pt-Ir/NaY bimetallic catalyst showed a higher activity and better activity maintenance than those of Pt/NaY catalyst in n-heptane reforming reaction.