Mo-modified Pt/CeO2 nanorods with high propane catalytic combustion activity: Comparison of phosphoric, sulphuric and molybdic acid modifications

Abstract

Catalytic combustion is the most commonly used reaction to purify VOCs. The activation and dissociation of the CH bond over the catalyst becomes a key factor in controlling the rate of the reaction. To identify the factors promoting CH bond decomposition and the roles played by the acidity of the catalyst in propane catalytic combustion, molybdic acid, phosphoric acid, and sulfuric acid were used to acidify CeO2 nanorods, and Pt was then loaded onto the nanorods. The Mo acid modified Pt/CeO2 catalyst purified more than 90% of propane at a high space velocity of 150,000 mL/(g·h) and 300 °C, which is a significant improvement over the Pt/CeO2 catalyst. XRD patterns and TEM images showed that the crystal structure and morphology of CeO2 were not damaged by acid modification. XPS, in situ CO-DRIFTs, NH3-TPD, H2-TPR and other characterization methods were used on Mo acid modified catalysts to explore the reasons for the improved catalytic performance. The results showed that Pt2+ and Pt4+ coexist on 1% Pt/CeO2-18Mo catalyst, and there are more acidic sites, redox sites and adsorbed oxygen. The reaction order test showed the reaction order of molybdic acid modified catalyst to oxygen is -0.4, which is higher than other catalysts, meaning that oxygen is difficult to inhibit the reaction on the catalyst surface. Finally, in situ DRIFTs proved that 1% Pt/CeO2-18Mo catalyst had strong propane adsorption and activation capacity. This catalyst provides new insight into how VOCs can be eliminated more efficiently, green and economically.