Abstract
Ceria-modified Pt/Al2O3 catalyst has been commonly prepared by the impregnation of platinum on ceria-modified alumina and widely applied in the chemical industry and automotive industry. The in situ diffuse reflectance infrared Fourier transformed spectroscopy (DRIFTS), and thermogravimetric (TG) analysis techniques were employed to investigate the typical mechanisms of the bis(ethanolammonium)hexahydroxyplatinate(IV) and cerium nitrate decomposition catalyzed by Ptδ+ species for the facile synthesis of CeO2-Pt/Al2O3 catalyst. It was found that Pt4+-catalyzed decomposition of cerium nitrate leads to the higher dispersity of ceria and forming more active oxygen species, on the basis of X-ray diffraction (XRD) and H2 temperature-programmed reduction (H2-TPR) results. The in situ activity measurements were also performed to investigate the reaction mechanisms and the specific activities for the catalytic CO, NO, C3H6 and C3H8 co-oxidation. The results indicate that undesirable N2O by-product is formed by the selective catalytic reduction (SCR) of NO by C3H6 below 350 °C. The cerium addition effectively improves the activity of catalytic oxidation, but exhibits an increased N2O yield, due to the increased reducibility.
Highlights
Platinum-based catalysts have been widely used in the chemical industry for the catalytic dehydrogenation of light alkanes, such as ethane and propane [1,2], as well as the automotive industry to catalytically oxidize harmful pollutants, including CO, NO, and hydrocarbons [3,4,5,6]
CeO2 -Pt/Al2 O3 catalyst for CO and C3 H8 conversions are higher than the corresponding T50 gaps, reaching 41.2 ◦ C and 92.0 ◦ C, respectively. These results indicate that the ceria addition significantly promotes low-temperature catalytic oxidation of CO, NO, C3 H6 and C3 H8, which agree well with the literature [10,13,16,20]
It was observed that Pt-catalyzed decomposition of cerium nitrate effectively increases the dispersity of ceria and significantly promotes the formation of activated surface oxygen species
Summary
Platinum-based catalysts have been widely used in the chemical industry for the catalytic dehydrogenation of light alkanes, such as ethane and propane [1,2], as well as the automotive industry to catalytically oxidize harmful pollutants, including CO, NO, and hydrocarbons [3,4,5,6]. Ceria has been used in automotive catalysts, due to its oxygen storage capacity and the ability to stabilize active metals [7,8,9]. It was reported that the synergy between ceria additive and active Pt species has a positive impact on the stability of coordinately unsaturated Pt2+ and Pt4+ species, thereby drives C–C and C–H bonds activation and promotes low-temperature oxidation of propane [10]. Ceria can stabilize atomically dispersed ionic platinum (Pt2+ species) to accelerate CO oxidation at low temperature [11]. Bruix [12] et al suggested that the unsaturated
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