¹²⁹Xe NMR proof for the distribution of platinum species during Pt/NaY preparation by H₂PtCl₆ impregnation and Pt(NH₃)₄²⁺ cation exchange methods

¹²⁹Xe NMR spectroscopy was used to measure the distribution of platinum species during the preparation of Pt/NaY catalysts by the impregnation of H₂PtC_l6 or the cation exchange of Pt(NH₃)₄²⁺ into a NaY zeolite. The location of platinum species during the impregnation was found to be affected by the impregnation time and the drying mode. More uniform distributions of platinum species in the impregnation were achieved by longer thermal treatments in a 100% relative humidity chamber before calcination. However, the cation exchange method gave uniform distribution of Pt species in the zeolite channel throughout the ion exchange, calcination, and reduction. This result was consistent with the rate of H₂PtCl₆ adsorption on the NaY zeolite in aqueous solution and the platinum metal dispersion of the Pt/NaY samples.