CO oxidation over Pt-modified CuO catalysts in the presence of water vapour and SO2

Abstract

The optimal Pt-modified CuO supported on γ-Al₂O₃ and γ-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 200^oC and 350^oC 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 γ - 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