PROTON-LOADED ZEOLITES .1. HX (X = CL, BR, I) IN SODIUM ZEOLITE-Y ARCHETYPE - PACKAGED ACIDS ON THE ROAD TO INTRAZEOLITE SEMICONDUCTORS

This series of three papers is concerned with an in-depth investigation of proton-loaded zeolites (packaged acids), a novel class of controlled microporosity, solid-state Brønsted acids. Proton-loaded zeolites are formed from the reaction between anhydrous Brønsted acids and dehydrated zeolites. Initial experiments focus attention on the chemistry, spectroscopy, diffraction, and dynamics of the sorption and desorption of anhydrous hydrogen halides (HX) in zeolite Y with some important control experiments in all-silica zeolite Y (SiO2-Y) and ALPO-5. Zeolite cation, HX anion, H/D isotope, and probe-base effects are explored to elucidate details of location, population, distribution (homogeneity), thermal/kinetic stability, acidity, and reactivity of protonation, anionation, and solvation sites in the zeolite Y lattice. Studies designed to probe the OH bond strength, acidity, solvation, and H/D isotope-exchange characteristics of proton-loaded zeolite Y leave little doubt that protonated oxygen framework sites and Brønsted acid sites in zeolite Y are for most purposes "identical". This study also alerts one to the fact that the types of adsorption, ionization, charge separation, and solvation phenomena that ensue following the sorption of anhydrous HX into zeolite Y have an important bearing on the designed synthesis of monodispersed intrazeolite semiconductor halide, sulfide, and phosphide quantum dots, wires, and supralattices that can be formed from similar kinds of acid-base reactions between anhydrous HX, H2S, and PH3, and extraframework cations in zeolite Y. The first part of this study focuses attention on the sodium zeolite Y system, which is considered as the archetypical model for the proton-loaded zeolite. This is followed in the second part with investigations relating to acidity, cation, and dehydrohalogenation effects of proton-loaded zeolites and how they compare with normal Brønsted acid zeolites and their decationization properties. The last part of this study enquires into the protonation of Brønsted acid zeolite Y, as well as the cation-free dipolar hydrophilic lattice of ALPO-5 and the hydrophobic lattice of SiO2-Y. © 1990 American Chemical Society.