DIFFUSION OF SILVER IONS IN ZEOLITE-Y PRECEDED BY A COUPLED CHEMICAL-REACTION - ELECTROCHEMICAL OBSERVATION AND MODELING

It is the goal of this work to show that the complex chronoamperometry of partially silver ion exchanged Ag3.1Na52.9Y can be understood by t reating the passage of silver cations to the electrode solution interf ace as a diffusion-controlled reaction preceded by a feeding chemical step. This is achieved via the solution of a CE (chemical followed by electrochemical) process using simulation methods adopting a finite di fference approach whereupon the zeolite is divided into a set of discr ete volume elements corresponding to the large and small channels of z eolite Y. The fit with the experimentally recorded chronoamperometry o f a monograin Ag3.1Na52.9Y-modified electrode covers 30 s after the ap plication of the pulse. Using this approach, accurate determinations o f intrazeolite diffusion coefficients will be possible only when exact equilibrium cation locations are known.