(2021) Catalysts_Enhanced catalytic soot oxidation by ce-based MOF-derived ceria nano-bar with promoted oxygen vacancy

Tsai Y.-C., Lee J., Kwon E., Huang C.-W., Huy N.N., You S., Hsu P.-S., Da Oh W., Lin K.-Y.A.

(MDPI) Catalysts ISSN: 20734344 Vol.11 Issue.9 Article No.1128 DOI: 10.3390/catal11091128

As CeO₂ is a useful catalyst for soot elimination, it is important to develop CeO₂ with higher contact areas, and reactivities for efficient soot oxidation and catalytic soot oxidation are ba-sically controlled by structures and surface properties of catalysts. Herein, a Ce-Metal organic framework (MOFs) consisting of Ce and benzene-1,3,5-tricarboxylic acid (H₃BTC) is employed as the precursor as CeBTC exhibits a unique bar-like high-aspect-ratio morphology, which is then transformed into CeO₂ with a nanoscale bar-like configuration. More importantly, this CeO₂ nano-bar (CeONB) possesses porou, and even hollow structures, as well as more oxygen vacancies, enabling CeONB to become a promising catalyst for soot oxidation. Thus, CeONB shows a much higher catalytic activity than commercial CeO₂ nanoparticle (comCeO) for soot oxidation with a signifi-cantly lower ignition temperature (Tig). Moreover, while soot oxidation by comCeO leads to production of CO together with CO₂, CeONB can completely convert soot to CO₂. The tight contact mode also enables CeONB to exhibit a very low Tig of 310 °C, whereas the existence of NO also enhances the soot oxidation by CeONB to reduce the Tig. The mechanism of NO-assisted soot oxidation is also examined, and validated by DRIFTS to identify the formation and transformation of nitrogen-containing intermediates. CeONB is also recyclable over many consecutive cycles and maintained its high catalytic activity for soot oxidation. These results demonstrate that CeONB is a promising and easily prepared high-aspect-ratio Ce-based catalyst for soot oxidation. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

This work is supported by the Ministry of Science and Technology (MOST)(110-2636-E-005-003-), Taiwan, and financially supported by the “Innovation and Development Center of Sustainable Agriculture” from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE), Taiwan.