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Effect, of the supported Pt on the migration of structural Ga toward the surface of catalysts of the Pt/H[Ga]ZSM5 type

Abstract:

The aim of this work is to find out how platinum supported over a gallosilicate of the MFI type influences the removal of Ga from the framework and affects the properties of the Pt/H[Ga]ZSM5 catalysts. In this regard, a gallosilicate and an aluminosilicate of MFI structure, with a Si/M ratio -15 (M = Ga, Al) were synthesized and characterized by XRD, nitrogen physical adsorption at -196 °C and chemical analysis by ICP-AES. Afterwards, they were used to prepare the following bifunctional catalysts: xPt/ H[Ga]ZSM5 (x = 0.10, 0.50 and 1.00 wt.% Pt) and 1.00%Pt/H[Al]ZSM5, which were characterized by ICP-AES, TEM, XPS, and the model reaction of toluene hydrogenation. The results found show dispersions within 50-80% for the supported platinum; the XPS analysis indicated a decrease in the Si/Ga ratio as a response to the increase of Pt content, suggesting a substantial influence of platinum on the migration of structural Ga toward the surface of the catalysts. This nonframework gallium remains oxidic and appears to strongly interact with Pt, which considerably affects the hydrogenating ability of these catalysts.