Assignment of the Hydroxyl Bands in the Infrared Spectra of Zeolites X and Y: Part 2.—After Different Pretreatments

Abstract

The i.r. absorption curve of “ deep bed ” calcined NH4Y zeolites could be broken down into the same components as HY zeolites. The frequency of the peaks was slightly changed, but their half band width remained constant. In a scries of treatments representing increasing hydrolysis non-acidic OH bands around 3680 and 3600 cm-1 increase in intensity, due to surface OH groups near Al defect locations. Polynuclear Al species bridging the cubo-octahcdra are suggested to be partly responsible for the increased thermal stability. The non-acidic OH bands in synthetic faujasites exchanged with polyvalent cations are explained on the same basis, since they behave in a similar way as the non-acidic bands on “ deep bed ” zeolites after different treatments.