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 pelletized form from Pt-zeolite powder which is prepared by calcination and reduction of [Pt (NH3) 4] ion supported on zeolite powder by ion exchange method. In this study, platinum was supported onto pre-pelletized zeolite by an ion exchange method using tetraammineplatinum (II) dichloride and hydroxopentaammineplatinum (IV) trichloride, hereafter referred to simply as Pt (II) ammine and Pt (IV) ammine, and their adsorption behavior and catalytic activity were compared. A substantial difference in the distribution of platinum into the pellets was observed between 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 catalyst from Pt (IV) ammine showed lower temperature performance than Pt (II) ammine in the catalytic combustion of methane.