Journal article

Authors list: Wang, Yu; Gallego, Jaime; Wang, Wei; Timmer, Phillip; Ding, Min; Luciano, Alexander Spriewald; Weber, Tim; Glatthaar, Lorena; Guo, Yanglong; Smarsly, Bernd M.; Over, Herbert

Publication year: 2023

Pages: 250-264

Journal: Chinese Journal of Catalysis

Volume number: 54

ISSN: 0253-9837

eISSN: 1872-2067

DOI Link: https://doi.org/10.1016/S1872-2067(23)64547-4

Publisher: Elsevier

Abstract: 

The exsolution process enables to produce and control the formation of stable and catalytically active nano particles via reductive extraction of uniformly incorporated precious metal ions from a solid oxide solution. Here we consider the simple and stable perovskite LaFeO₃ (LFO) where 10% of Fe on B sites are substituted by ruthenium (LFRO). Hydrogen reduction of LFRO at 800 °C leads to the formation of socketed ruthenium particles whose low-temperature activity in the total propane oxidation reaction at 210 °C is substantially lower than that of the original LFRO. Upon increasing the reaction temperature once to 400 °C, the exsolved catalyst undergoes self-activation so that the activity at 210 °C turns out to be five times higher than that of the original LFRO. High-resolution transmission electron microscopy and nanometer-resolved element mapping, together with averaging characterization methods, including X-ray diffraction and X-ray photoelectron spectroscopy, Raman spectroscopy, and diffuse infrared spectroscopy, unveil that after reduction at 800 °C the exsolved Ru particles are slightly alloyed with Fe and encapsulated by an inert and protecting LaO_x layer. Mild oxidative treatment at 400 °C leads to the removal of the conforming LaO_x layer, while the uncovered RuFe alloy particle transforms to catalytically active oxidic Ru species, with no indication of a separate FeO_x phase. We exemplify with our case study of LaFe_0.9Ru_0.1O₃ that careful redox treatment enables to control the exsolution process and to avoid deactivation. This may be of importance for the whole class of exsolvable materials.

Harvard Citation style: Wang, Y., Gallego, J., Wang, W., Timmer, P., Ding, M., Luciano, A., et al. (2023) Unveiling the self-activation of exsolved LaFe0.9Ru0.1O3 perovskite during the catalytic total oxidation of propane, Chinese Journal of Catalysis, 54, pp. 250-264. https://doi.org/10.1016/S1872-2067(23)64547-4

APA Citation style: Wang, Y., Gallego, J., Wang, W., Timmer, P., Ding, M., Luciano, A., Weber, T., Glatthaar, L., Guo, Y., Smarsly, B., & Over, H. (2023). Unveiling the self-activation of exsolved LaFe0.9Ru0.1O3 perovskite during the catalytic total oxidation of propane. Chinese Journal of Catalysis. 54, 250-264. https://doi.org/10.1016/S1872-2067(23)64547-4