Readsorption and diffusion limited TPD of water from zeolite Linde 4A

A. PALERMO Y C. M. ALDAO

THERMOCHIMICA ACTA

Año: 1998 vol. 319 p. 177 - 184

0040-6031

Coupled effects due to diffusion and readsorption of desorbed species on temperature-programmed desorption (TPD) data have been analyzed and compared with experimental curves during TPD of water from zeolite Linde 4A. The effects of different heating rates and carrier-gas ¯ow are considered explicitly. A simple model is presented which allows straightforward extraction of kinetic parameters from the experimental data, even in the presence of effects due to readsorption and diffusion. In this system, it is found that an extensive readsorption of gas occurs within the zeolite pellet and the local adsorbate coverage is governed by equilibrium adsorption. We found that neglecting the effects of diffusion can cause activation energy falsi®cations of the order of 10%. When readsorption and diffusion are not taken into account, calculated pre-exponential factors are very small and convey no direct physical meaning.