Effect of Water Molecule on Photo-Assisted Nitrous Oxide Decomposition over Oxotitanium Porphyrin: A Theoretical Study

• Main Authors: Phornphimon Maitarad, Vinich Promarak, Liyi Shi, Supawadee Namuangruk
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Catalysts
• Subjects: metal-porphyrin; n₂o decomposition; reaction mechanism; catalysis; density functional theory
• Online Access: https://www.mdpi.com/2073-4344/10/2/157

Water vapor has generally been recognized as an inhibitor of catalysts in nitrous oxide (N₂O) decomposition because it limits the lifetime of catalytic reactors. Oxygen produced in reactions also deactivates the catalytic performance of bulk surface catalysts. Herein, we propose a potential catalyst that is tolerant of water and oxygen in the process of N₂O decomposition. By applying density functional theory calculations, we investigated the reaction mechanism of N₂O decomposition into N₂ and O₂ catalyzed by oxotitanium(IV) porphyrin (TiO-por) with interfacially bonded water. The activation energies of reaction Path A and B are compared under thermal and photo-assisted conditions. The obtained calculation results show that the photo-assisted reaction in Path B is highly exothermic and proceeds smoothly with the low activation barrier of 27.57 kcal/mol at the rate determining step. The produced O₂ is easily desorbed from the surface of the catalyst, requiring only 4.96 kcal/mol, indicating the suppression of catalyst deactivation. Therefore, TiO-por is theoretically proved to have the potential to be a desirable catalyst for N₂O decomposition with photo-irradiation because of its low activation barrier, water resistance, and ease of regeneration.