Catalytic Combustion of Styrene over the Binary Mixture of Manganese and Copper Based Catalyst in the Absence and Presence of Water Vapor

Resumo

MnO_x and MnCu based catalysts prepared by ultrasonic impregnation methods were characterized by XRD, TPR-H₂, XPS and N₂ adsorption and tested for styrene combustion in the presence and absence of water vapor. Results showed that the loading of binary mixtures of manganese oxide and copper oxide on γ-Al₂O₃ increased the ratio of Cu⁺/Cu²⁺ of the defect spinel of Cu_1.5Mn_1.5O_4–x and the reducibility of the catalyst and in this way increased the catalytic activity of the catalysts for styrene combustion. The catalyst MnCu/γ-Al₂O₃ (20%/l) with 20 wt % loading amount and the Mn/Cu ratio of 1 : 1 showed the highest catalytic activity with T₉₀ = 214°C. Water vapor in feed steam decreased the activity of the catalysts MnCu/γ-Al₂O₃ (20%/l) and Mn₂O₃/γ-Al₂O₃ (10%). The catalyst MnCu/γ-Al₂O₃ (20%/l) had more resistant to negative influence of water vapor. Upon addition of 2.94 vol % water vapor to the feed stream a 6.5% decrease in styrene conversion was observed whereas for the catalyst Mn₂O₃/γ-Al₂O₃ (10%) a 14% reduction in conversion at the same condition was recorded. Higher resistance to the negative influence of water vapor could be due to weaker interactions between water molecules and the surface of catalyst.