INSITU CHARACTERIZATION OF HETEROGENEOUS CATALYSTS BY MOSSBAUER-SPECTROSCOPY

The application of Mossbauer spectroscoPY to the in situ characterisation of heterogeneous catalysts is illustrated here by studies of three different systems. Firstly the use of Fe-57- and Ir-193- Mossbauer spectroscopy to monitor the prereduction of silica-supported iron-iridium catalysts in hydrogen and the formation of iron carbides following subsequent treatment in hydrogen and carbon monoxide is discussed. Secondly, Sn-119 Mossbauer spectroscopic studies of titania-supported platinum-tin catalysts have been performed which demonstrate how the method can identify unexpected changes during reduction. Finally Eu-151 Mossbauer spectroscopy has been used to show that the reduction of Eu3+ in hydrogen is more easily achieved in Eu3+-exchanged Y-zeolite than in europium(III) oxide.