Synthetic Faujasites Research Articles

Crystal field effects in ion-exchanged faujasites

Paramagnetic spin resonance spectroscopy has been applied to the study of small amounts of Cu 2+ in synthetic faujasites containing K + through Mg 2+ as the major compensating cation. Dehydration results in spectral changes corresponding to a transition from distorted octahedral to square-planar symmetry for the Cu 2+ ion. As the cation changes from K + to Mg 2+, its increasing polarizing power, e r , results in a shift of electron charge distribution to these ions, with an increased energy of the d x 2 − y 2 levels of the copper.

Optical and EPR spectral studies of structure of the adsorption centers of chromia-alumina catalysts

Adsorption of n-hexane and benzene on sodium and demetallated synthetic faujasites at elevated temperatures was measured gravimetrically. Hexane was adsorbed with nearly equal heats of adsorption on sodium and demetallated Y zeolites; no preferential adsorption sites were detected. Heats of adsorption on NaY were less than on NaX because of reduced negative charge on the zeolite lattice. Benzene was also adsorbed on NaY nonspecifically but more strongly than was hexane. Both Bronsted acid sites in hydrogen Y and Lewis sites in decationized Y apparently serve as preferential sites for adsorption of benzene.