Issue 38, 2021

Hierarchical macroparticles of ceria with tube-like shape – synthesis and properties

Abstract

This work presents the results of a multi-technique (HRTEM – high resolution transmission electron microscopy, EDX – energy-dispersive X-ray spectroscopy, XRD – X-ray diffraction and H2-TPR – temperature programmed reduction by H2) study on the hierarchical organization of Yb-doped ceria nanocrystals (Ce1−xYbxO2−x/2) into tube-like macro-particles. Hierarchically organized ceria-based mixed oxides (macroparticles) were prepared by a wet chemical method. It was observed that the predetermined shape of the investigated macroparticles was kept up to x = ∼0.2. Above this value, additional forms (like large, un-shapely aggregates of the nanoparticles) were created. A very important feature of these materials is the very high shape stability, even at high temperatures. The overall shape of the macroparticles remained unchanged even at up to 900 °C. Moreover, the effect of the hierarchical arrangement of nanocrystallites into the tube-like macroparticles on the activity for propane oxidation and soot combustion reactions has been investigated. The CeO2 nanopowder (prepared by the microemulsion technique) was used as an example of an unorganized structure. It was concluded that the presence of a 3D structure composed of CeO2 nanocrystals significantly improves the catalytic activity of the tube-like material in comparison to the ceria nanopowder. The investigated oxides are good candidates for catalysts of soot oxidation. For the tube-like ceria, the temperature of half oxidation (T50% = 468 °C) was 62 °C lower than that for the nanopowder (T50% = 538 °C) and 103 °C lower than that for non-catalysed oxidation (T50% = 592 °C). Moreover, introduction of Yb3+ ions into the ceria matrix led to further improvement of the propane oxidation performance. For the tube-like Ce0.9Yb0.1O1.95, the temperature of half oxidation (T50% = 455 °C) was 40 °C lower than that for undoped tube-like CeO2 (T50% = 495 °C) and 95 °C lower than that for the ceria nanopowder (T50% = 550 °C).

Graphical abstract: Hierarchical macroparticles of ceria with tube-like shape – synthesis and properties

Supplementary files

Article information

Article type
Paper
Submitted
08 六月 2021
Accepted
17 八月 2021
First published
17 八月 2021

CrystEngComm, 2021,23, 6743-6754

Hierarchical macroparticles of ceria with tube-like shape – synthesis and properties

M. A. Małecka and P. Woźniak, CrystEngComm, 2021, 23, 6743 DOI: 10.1039/D1CE00755F

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