An ESR Study of Titanium(III) Exchanged Zeolite A.

A comparison of the chemical reactivity of Ti(III) cations in A-type and Y-type zeolite lattices has been performed by the use of electron spin resonance. While the state of the Ti(III) cation, as observed by ESR spectroscopy, appears similar in the two types of lattices, the reactions of adsorbed gases with the two types of titanium(III)-exchanged zeolites are strikingly different. The adsorption of sulfur dioxide leads to the formation of Ti(IV)-SO/sub 2//sup -/ in the zeolite Y lattice while Ti(IV)-SO/sub 3//sup -/ is formed in the A-type lattice. Adsorption of oxygen results in the formation of Ti(IV)-O/sub 2//sup -/ in the Y-type lattice, as it does in the A-type lattice at low pressures. However, at elevated oxygen pressure a new radical is formed in the A-type lattice which ESR and ESCA evidence strongly suggests is of the form Ti(IV)-O/sub 4//sup -/.