INFLUENCE OF PLATINUM AMMINE COMPLEX ION SPECIES ON THE PREPARATION OF PRE-PELLETIZED ZEOLITE-SUPPORTED PLATINUM CATALYSTS

Usually, platinum supported on zeolite catalyst is applied as a pellet ized form from Pt-zeolite powder which is prepared by calcination and reduction of [Pt(NH3)(4)](++) ion supported on zeolite powder by ion e xchange method. In this study, platinum was supported onto pre-pelleti zed zeolite by an ion exchange method using tetraammine-platinum(II) d ichloride and hydroxopentaammineplatinum (IV) trichloride, hereafter r eferred to simply as Pt(II) ammine and Pt(IV) ammine, and their adsorp tion behavior and catalytic activity were compared. A substantial diff erence in the distribution of platinum into the pellets was observed b etween the platinum ammine complex ion species. Pt(IV) ammine resulted in egg shell-type supported catalysts. The behavior was studied as a diffusion control of Pt complex ion in the pellet from the results of the relations between Pt penetration depth and soaking time. The catal yst from Pt(IV) ammine showed lower temperature performance than Pt(II ) ammine in the catalytic combustion of methane.