TRANSMISSION ELECTRON-MICROSCOPY AND ENERGY-DISPERSIVE X-RAY SPECTROSCOPY STUDIES OF PT-SN GAMMA-AL2O3 CATALYSTS/

A series of Pt-Sn/gamma-Al2O3 reforming catalysts have been prepared a nd studied by transmission electron microscopy (TEM) and energy-disper sive X-ray spectroscopy (EDX). It has been shown that the catalyst per formance is dependent on the way in which the catalyst had been prepar ed. The majority of the tin was in the ionic state as Sn(II) while a m inor part of the tin was reduced to the metallic state by platinum. Pt -Sn alloys were found together with platinum particles in the bimetall ic catalysts. A significant number of very small TEM-invisible platinu m particles less than 1 nm in diameter were present in addition the TE M-visible platinum particles. Particle aggregation and alloy formation occurred during the use of the catalysts in the reforming of octane. (C) 1996 Academic Press, Inc.