THE EFFECT OF NH3 ON THE IONIC-CONDUCTIVITY OF DEHYDRATED ZEOLITES NA-BETA AND H-BETA

The effect of NH3 in concentrations up to 25 ppm on the electrical pro perties of the dehydrated forms of the zeolites Na beta and H beta was examined by use of complex impedance spectroscopy in a frequency rang e of 10 Hz-10 MHz and a temperature range of 400-723 K. Whereas the io nic conductivity of Na beta is unaffected, NH3 promotes proton conduct ion in H beta. This is reflected by an increase of the specific conduc tivity, which is directly proportional to the NH3 concentration, as we ll as by a decrease of the corresponding activation energy. A Grotthus -like conduction mechanism is supposed for the proton transport in the presence of NH3. (C) 1998 Elsevier Science B.V. All rights reserved.