Modified LaMnO3 perovskite oxide as NOx storage and reduction catalyst for emission control of hydrogen internal combustion engines

• Published in: Fuel (Guildford) Vol. 375; p. 132500
• Main Authors: Zou, Yingtong, Xu, Guangyan, An, Yingsheng, Zhang, Mengyuan, Sun, Yanwei, Liu, Zhi, Yu, Yunbo, He, Hong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2024
• Subjects: Active site regeneration; Hydrogen internal combustion engines; La-based perovskite oxides; NOx storage and reduction; Oxygen vacancies; La-based perovskite oxides; Oxygen vacancies; NOx storage and reduction; Hydrogen internal combustion engines; Active site regeneration
• ISSN: 0016-2361
• DOI: 10.1016/j.fuel.2024.132500

[Display omitted] •The NSR technique is suitable for NOx abatement on H2-ICE using on-board H2 as a reductant.•Porous LaMnO3 with oxygen vacancies was fabricated by the Pechini-P123 (PC-P) method.•LMO-PC-P facilitated NO oxidation via hyponitrite on oxygen vacancies in the storage process.•The maximum NSC value of LMO-PC-P was two times larger than that of the regular Sol-Gel sample.•LMO-PC-P exhibited a wide active temperature window in dynamic NSR cycles with high total NOx conversion. As the flagship of zero-carbon emission in transportation, hydrogen internal combustion engine vehicles alleviate global warming pressure but are still restricted by high emission of nitrogen oxides (NOx). A promising approach to reduce NOx emission is the NOx storage and reduction (NSR) technique using on-board H2 as the reductant. As a new generation of NSR catalysts, La-based perovskite oxides are plagued by small specific surface areas and poor reactivity, thus restricting their usability. Here, we proposed to simply fabricate a porous LaMnO3 perovskite oxide via the Pechini method (PC) with the addition of a pore-forming agent, Pluronic 123 (P123). The modified LaMnO3 catalyst (LMO-PC-P) obtained by the PC-P method exhibited a large specific surface area and abundant oxygen vacancies. Such a structural feature not only provided more active sites for NOx storage but also facilitated NO oxidation via forming hyponitrite (N2O22−) rapidly on the defective surface under fuel-lean conditions. As a result, an excellent static NOx storage capability (NSC) was achieved, with a maximum NSC value of 205 μmol/g, which was over two times larger than that of LaMnO3 prepared by the Sol-gel method (LMO-SG). Over the LMO-PC-P sample, meanwhile, desorption of NOx in the fuel-rich mode was promoted, thus benefiting the regeneration of active sites. In the dynamic NSR test, the optimized catalyst achieved 84 % conversion of NOx at 350 °C, while the value for LMO-SG under the same conditions was only 46 %. This study presents a convenient and practical approach for preparing porous and defective NSR perovskite oxide catalysts for NOx emission control in hydrogen internal combustion engine vehicles.