Reduction–agglomeration model for metal dispersion in platinum-exchanged NaX zeolite

Abstract

The metal-particle size distribution in reduced platinum faujasite X, resulting from the temperature-programmed autoreduction of decomposing tetra-ammine complexes and the subsequent agglomeration of the generated platinum atoms, has been evaluated from transmission electron micrographs and is described and simulated by an atom-capture model. The reduction and agglomeration process is found to depend on the degree of ion exchange, the extent of dehydration, the medium used in the autoreduction, the heating rate and the constraints imposed by the zeolite matrix.