CO oxidation over Pt-modified CuO catalysts in the presence of water vapour and SO2
Abstract
The optimal Pt-modified CuO supported on g-Al2O3 and g-Al2O3 + CeO2 catalysts have been prepared. Physico-chemical characteristics of catalysts were investigated and determined by the methods of N2 adsorption (BET), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), and hydrogen pulse chemisorption (HPC). The characteristics of carbon monoxide (CO) adsorption on catalysts were defined by the method of infrared spectroscopy (IR) in the range of 4000 – 400 cm-1. The effect of the mixture of water vapour and SO2 on the activity of these catalysts for the CO oxidation was assessed. Reactions were conducted at 200oC and 350oC in the absence and presence of the mixture of water vapour (1.1 mol %) and SO2 (0.0625 mol %). Concentrations of O2 and CO in the gas mixture were 9.2 mol % and 0.5 mol %, respectively. The results showed that in the catalysts there exist highly active centers Cu1+ and Pt2+. On the catalysts the adsorption of CO on Cu2+, Pt2+, CeO2, and g-Al2O3 centres was observed. Addition of CeO2 led to increase the reductivity, CO adsorption but decrease in specific surface area of catalyst. The result PtCu/CeAl catalyst shown higher active, but lower stability compared to PtCu/Al catalyst. The mixture of water vapour and SO2 showed the reversible poisoning toward the Pt-CuO catalysts at a temperature of 350 oC, but irreversible at 200 oC.