SOLID-STATE ION-EXCHANGE IN BETA-ZEOLITES - II SYSTEMS AMMONIUM CHLORIDE NA-BETA, CS-BETA AND H-BETA/

The solid-state interaction between NH4Cl and Na-, Cs- and H-beta zeol ites was followed using temperature-programmed evolution/mass spectrom etry (TPE/MS) and thermal analysis (TA) of 1-propylamine (1-PA) desorp tion for proton acidity determinations. The guest salt NH4Cl undergoes a decomposition to NH3 and HCl upon grinding and subsequent heating o f the mixture with alkaline-beta zeolites, and an exchange reaction oc curs with the cations of the host zeolite. The degree of exchange was found to depend on the guest/host ion concentration and the temperatur e. During this solid-state interaction a non-volatile alkaline-chlorid e salt is formed, which participates in a reverse reaction, depending on the temperature. A study of these systems permitted some peculiarit ies of the re-exchange process to be examined. (C) 1998 Elsevier Scien ce B.V. All rights reserved.