Analysis of temperature-programmed reduction profiles from metal-supported catalysts

Abstract

An experimental procedure is proposed to enable analysis of H2 emission/consumption data obtained during temperature-programmed reduction (TPR) of a metal-supported catalyst. Using the methods described allows one to account for chemical processes other than reduction and thus remove their contribution from the TPR profile. The resulting “real” TPR spectrum is a signature that reflects only reduction processes that occur under nonisothermal conditions. To demonstrate the methodology, Pt, Ir, and PtIr supported on alumina have been characterized. The real TPR profile of the bimetallic catalyst is not the simple superposition of the reduction spectra of the monometallics. This observation has generally been considered indicative of some type of alloy-phase formation. On the other hand, had the hydrogen emission/consumption data been used directly, the same conclusion would be tenuous.