Abstract
AbstractThermal decomposition of noble metal oxide phases formed during aging in air on industrially manufactured γ‐Al2O3‐supported Rh catalysts was investigated. Some of the catalyst washcoats were modified by various stabilizers, promoters and oxygen storage components, such as La2O3, CeO2 and Ce–Zr mixed oxide. In order to investigate the effect of aging, stabilizers and manufacturing method on the thermal stability of the noble metal oxide phases formed, a stepwise thermal decomposition in high vacuum (pressure <10−7 Torr) was performed. X‐ray photoelectron spectroscopy (XPS) was used to observe the changes in chemical state after each annealing cycle. Our results show marked differences in the rate of reduction between different Rh catalysts. Disposition of the Rh oxides towards reduction was also investigated by exposing the catalysts to 400 mbar of H2 at 300°C for 30 min. After 3 h of aging in air at 1000°C an irreducible rhodium oxide, which was identified to be either Rh2O3 diffused into alumina or RhO2 in intimate contact with the alumina surface, was formed regardless of the Ce–Zr mixed‐oxide additive and manufacturing method of the catalyst. Copyright © 2002 John Wiley & Sons, Ltd.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
