High-temperature resistant BaO-Y2O3 catalysts with different morphologies for NO decomposition and mechanism study

• Published in: Fuel (Guildford) 2024-07, Vol.368, p.131638, Article 131638
• Main Authors: Xu, Kangwei, Qin, Chunlan, Deng, Runjie, Zhang, Wei, Song, Qianshi, Zhang, Lidong, Wang, Xiaohan
• Format: Article
• Language: English
• Subjects: BaO-Y2O3; DFT calculations; NO high-temperature decomposition; Oxygen vacancy
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2024.131638

[Display omitted] •Various shapes of BaO-Y2O3 catalysts are fabricated resisting to high temperature.•Catalysts’ large specific surface area and active metal bond lead to high activity.•Oxygen vacancies generated in high temperature facilitate the reaction process.•NO decomposition mechanism is revealed by in situ DRIFTS and DFT calculations. The high-temperature reaction is a common phenomenon in combustion society, and its catalytic response remain a tremendous challenge hampered by the activity and resistance of the catalyst to high temperatures exceeding 1000 ℃. Three distinct forms of BaO-Y2O3 catalysts—nanosphere, nanorod, and rod—were created using a hydrothermal method and high-temperature annealing to enable direct decomposition of NO. To gather reaction-relevant structural and property information for BaO-Y2O3, we combined reactor activity measurements, chemisorption and DFT studies to elucidate NO high-temperature decomposition process and pinpoint the critical role of oxygen vacancy. We have systematically clarified the increasing favorability of NO decomposition on the nano-catalysts (nanospheres and nanorods) at high temperatures is through stable lattice structure, large specific surface areas, high porosity, and active Ba–O–Y bond. Due to the attraction of electrons gathering in vacancies to NO molecules, oxygen vacancies created in situ at high temperatures, as validated by O2-TPD and density functional theory (DFT) calculations, are advantageous for NO adsorption and decomposition. Moreover, N2 formation pathway over Ba-Y2O3(111) structure is revealed by DFT calculations that NO molecules are apt to be caught by active sites, the region of Ba–O–Y, resulting in the production of N2O2 intermediate and its subsequent bond breaking to N2O as well as N2. In situ DRIFTS experiment further confirms the reaction mechanism via the detected adsorbed species, and clarify the significance of NO2− to O2 formation. In a nutshell, the synthetic combustion catalysts are effective in high-temperature environments that contribute to de-NOx combustion, and the insights into the adsorption configurations of reactant and intermediates unlock fundamental understanding for emissions gas chemistry.