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

Abstract

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.

Keywords

• metal-porphyrin
• n₂o decomposition
• reaction mechanism
• catalysis
• density functional theory