Abstrait

Promotion of Pt-Supported NaY Zeolite with Copper: Activity Towards Co Oxidation

Zeinhom M. El-Bahy, Ahmed I. Hanafy and Salah M. El-Bahy

Low temperature CO oxidation and adsorption over Cu-promoted and unpromoted PtY catalysts were investigated using in situ FTIR technique. The catalysts were prepared by ion exchange method of NaY in aqueous solutions of Pt2+ and/or Cu2+. The prepared catalysts were subjected to thermal treatment at 500°C prior to characterizations and gas adsorptions. The physicochemical characterization of the prepared solids was probed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), surface area measurements at -196°C, temperature programmed desorption (TPD) and in situ FTIR measurements of CO adsorption. The FTIR spectra and XRD patterns proved the preservation of zeolite structure after metals loading. Introduction of copper to Pt supported on Y zeolite decreased metal particle size from ≈ 20 to 14 nm as calculated from XRD patterns. The main product of CO+O2 adsorption was CO2, however, it was (–CO3 2-) in case of CO + H2O adsorption (water gas shift reaction, WGS). Cu-promoted PtY had a pronounced catalytic activity towards CO oxidation more than Cu-free PtY catalyst. The reduced catalysts showed higher catalytic activity towards CO oxidation more than that of the unreduced catalysts. A trace of H2O had a positive effect on CO oxidation in presence of O2 gas and enhanced the formation of CO2.