DETERMINATION OF CATALYTIC ACTIVE-SITES IN (CE3+, CA2+)-SUPPORTED Y-ZEOLITE BY FOURIER-TRANSFORM IR SPECTROSCOPY

Catalytic active sites in an aluminosilicate matrix Y zeolite were generated by exchange with calcium and cerium chloride solutions, followed by calcination. Acid properties of the (Ce, Ca)ex-NaY zeolite were studied by send quantitative (Fourier transform) IR spectroscopy of the pyridine adsorption. The molecular probe interacts with Bronsted active sites (BASs) and bonds coordinatively to Lewis active sites (LASs). The main observed frequencies were 1459 cm-1 (BAS) and 1443 cm-1 (LAS). It has been found that the BAS:IAS optical density ratio was ca. 1.4. The observed protonic active sites may be due to cerium cation-hydroxyl supported on the Y zeolite matrix under specific ion exchange and thermal conditions.