The role of carriers in properties and performance of Pt-CuO nanocatalysts in low temperature oxidation of CO and p-xylene

Cam Loc Luu, Tri Nguyen, Tien Cuong Hoang, Minh Nam Hoang and Cam Anh Ha

Abstract

In this study four optimal catalysts on the basis of Pt–CuO supported on γ-Al₂O₃, TiO₂, CeO₂ and γ-Al₂O₃ + CeO₂ have been prepared and studied. Characterizations of the catalysts have been carried out by methods of N₂ adsorption, x-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and temperature-programmed-reduction (TPR). The activity of these catalysts for deep oxidation of CO, p-xylene and their mixture was assessed at temperature range 75−300 °C. The results showed that the presence of CO in a mixture with p-xylene has a beneficial effect on the rate of p-xylene conversion; meanwhile the presence of p-xylene shows the inhibition on CO oxidation. In the reactions of the mixture, oxidation of CO and p-xylene occurred simultaneously on PtCuO catalyst supported on γ-Al₂O₃, TiO₂, CeO₂ carriers, but on catalyst PtCu/CeAl the oxidation of p-xylene can proceed only when CO is consumed entirely. Addition of 1.1 to 3.2% mol steam into the gas mixture exhibits no effect on the conversion of CO; meanwhile, it shows the limited effect on oxidation rate of p-xylene on hydrophobic catalysts (PtCu/Ce, PtCu/CeAl and PtCu/Ti), but strong inhibition on hydrophilic catalyst (PtCu/Al). However, this negative effect of water was reversible.