Ceria-silica mesoporous catalysts for CO preferential oxidation in H2-rich stream: The effect of Ce:Si ratio and copper modification

• Published in: Applied surface science Vol. 594; p. 153473
• Main Authors: Kaplin, Igor Yu, Lokteva, Ekaterina S., Maslakov, Konstantin I., Tikhonov, Artem V., Kharlanov, Andrey N., Fionov, Alexander V., Kamaev, Alexey O., Isaikina, Oksana Ya, Maksimov, Sergey V., Golubina, Elena V.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.08.2022
• Subjects: Ce:Si ratio; Ceria-silica; CO-PROX; Copper oxide; Copper-ceria interactions; Template; Copper-ceria interactions; CO-PROX; Copper oxide; Ce:Si ratio; Ceria-silica; Template
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2022.153473

[Display omitted] •Pristine and copper-modified CeSiOx systems were prepared by a template method.•Ce:Si ratio strongly affect catalytic properties in CO-PROX.•CuOy/CeSiOx with Ce:Si = 4:1 exhibits the best catalytic properties in CO-PROX.•It comprises uniform fine CeO2 NPs, Cu+ and has improved reoxidation ability. In this work mesoporous CeO2-SiO2 catalysts with the Ce:Si molar ratios of 1:1 and 4:1 were synthesized by template method and modified with copper to elucidate the role of copper-ceria and ceria-silica interactions in the catalyst efficiency in CO-PROX. The catalysts were characterized by SEM-EDS, AAS, XRD, TPR-H2, TEM, and spectroscopic methods (Raman, EPR and in situ DRIFT of adsorbed CO). The binary catalyst with the equimolar Ce:Si ratio demonstrated better catalytic performance in CO-PROX due to its favorable textural properties and strong ability to anion vacancy formation as confirmed by N2 physisorption and Raman spectroscopy. CuOx/CeSiOy (Ce:Si = 4:1) demonstrated better low-temperature activity, CO2 selectivity and stability than CuOx/CeSiOy (Ce:Si = 1:1) and both binary systems because of its unique structure, comprising fine CeO2 particles with a narrow size distribution of 2–3 nm well dispersed on a large surface area, high concentration of the most active in CO oxidation Cu+ sites, formed on CuOx-CeO2 interfaces, and improved ability to surface reoxidation after reduction with the reagents resulted in the decreased Ce3+ concentration. It was also stable in the presence of CO2 and H2O in the reaction mixture. These properties would be difficult to achieve via template preparation methods without SiO2 addition.