Dispersed Pr on Nickel Oxide for Efficient Nitrous Oxide Direct Decomposition in Simulated Nitric Acid Exhaust

Abstract

Nitrous oxide (N₂O) is a potent greenhouse gas with a high global warming potential. The N₂O direct decomposition (deN₂O) is currently the most widely used technique due to its operational simplicity and lack of secondary pollution. The presence of impurity gases in industrial exhaust increases the challenge of eliminating N₂O, urging the development of highly active and stable catalysts for its degradation. In this study, a series of praseodymium (Pr)-doped nickel oxide (NiO) catalysts were synthesized for N₂O degradation. These catalysts showed higher N₂O decomposition activity (T₁₀₀ = 400–440 °C) than pure NiO (T₁₀₀ = 480 °C) and also demonstrated high resistance to impurity gases in simulated industrial nitric acid tail gas. In the catalyst with a Pr to Ni ratio of 0.002, the highly dispersed Pr on the NiO surface regulated its particle size and increased specific surface area and pore volume. DFT calculations revealed that Pr significantly enhanced the electron-donating ability of Ni²⁺, facilitating the dissociative adsorption of N₂O on the catalyst surface, where O existed in the form of Ni³⁺-O*. Additionally, Pr reduced the desorption energy of O₂, the rate-determining step. During the reaction, Pr³⁺ transferred electrons to Ni³⁺ via f-d electron hopping, stabilizing the active Ni²⁺ sites and enabling an efficient catalytic reaction. These findings demonstrate the practical potential of this catalyst and provide new insights into the degradation of N₂O in industrial exhaust gases, offering a promising avenue for application.