STUDY ON THE REACTIVITY OF IN2O3 IN MIXTURES WITH AMMONIUM-ZEOLITES

In ground mixtures of In2O3 and NH4Y, incorporation of In+ cations int o the zeolitic phase occurs upon thermal treatment by partial reductiv e solid-state ion exchange associated with oxidation of ammonium ions or released ammonia to NZ and NH2OH. Cationic InO+ species, created in zeolites by reductive solid-state ion exchange of In2O3/NH4-zeolite m ixtures in hydrogen atmosphere and subsequent oxidation of the In+ lat tice cations by oxygen, do not undergo autoreduction up to 970 K. Redu ctive solid-state ion exchange easily proceeds in carbon monoxide atmo sphere at temperatures between 620 and 770 K. The significance of thes e observations for the use of indium-containing zeolites as catalysts is discussed.