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 series 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-octahedra 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.