Synthesis and Study of Acid-Basic Properties of Ti(IV) and Zr(IV) Phosphates Immobylized in the Matrix of Clinoptilolite

Abstract

By combination of the ionexchange and ionic-molecular layering methods [1], the synthesis of natural zeolite derivatives (clinoptilolite) containing in its composition nano-size fragments of Ti(IV) and Zr(IV) phosphates was performed. It was determined by the X-Ray method, that the phosphates of Ti(IV) and Zr(IV) replicate crystal lattice of zeolite, manifesting in enhancing the line's intensity on X-Ray patterns. The Brensted's and Lewis's spectra of acidic centers distributions were obtained by Hammett's indicator spectrophotometric method [2] in the interval of pK, values from -4.4 to 14.2, which have shown that P(V) of the derivatives is represented mainly by HPO₄- and H₂PO₄-groups, with predomination of these latter. It is shown that the force of Brensted's acidic centers, influenced by H₂PO₄-groups. remains at the level of H₂PO_(aq)-anion, and the force of the centers due to HPO₄-groups shifts into alkaline region, about 0,5 unit of pK. The strong acidic Lewis's centers were detected at the levels of pK, from 0 to -4.0. The spectra of Ti(IV) and Zr(IV) phosphates is presented in (1) and (2) respectively. A set of the acquired results makes possible a suggestion about using P(V)-containing derivatives in processes which are catalyzed both with Brensted's and Lewis's centers participation.