Preparation and characterization of Pt-dealuminated Y zeolite by TG/DTA and TPR

Abstract

Monometallic catalysts containing Pt supported on dealuminated Y zeolite were prepared by impregnation with a solution containing H2PtCl6·6H2O cationic complexes. The catalysts were calcined and characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), simultaneous thermogravimetry/differential thermal analysis (TG/DTA), temperature programmed reduction, physisorption of nitrogen, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX). The XRD results showed that zeolite Y maintained its crystalline structure throughout the dealumination and metal incorporation processes. However, the relative crystallinity of the various samples was reduced upon impregnation. Furthermore, the XRD diffractograms, the SEM and TEM micrographs, and EDX spectra for the impregnated samples presented evidence for the presence of Pt oxides. The adsorption isotherms of the nitrogen physisorption showed the existence of micropores and mesopores within the Pt/Y zeolite. Temperature programmed reduction profiles suggest that the reduction temperature of Pt depends on the location of the metal within the zeolitic structure. The reduction peaks can be attributed to cations located in the large cavities, sodalite cages, or hexagonal prisms. The TG/DTA analyses showed the endothermic decomposition of the Pt complexes deposited on the zeolite during impregnation.