Simultaneous Generation of Ammonia during Nitrile Waste Gas Purification over a Silver Single-Atom-Doped Ceria...

Catalytic elimination of toxic nitrile waste gas is of great significance for preserving the atmospheric environment, but achieving resource utilization during its destruction has been less explored. Herein, this study proposed a universal strategy for nitrile waste gas purification and NH₃ generation simultaneously. The developed silver single-atom-doped ceria nanorod (Ag₁/R-CeO₂) was endowed with near complete mineralization and around 90% NH₃ yield at 300-350 °C for the catalytic oxidation of both acetonitrile and acrylonitrile. The introduction of the Ag single atom created more surface oxygen vacancies, thereby promoting water activation to form abundant surface hydroxyl groups. As a benefit from this, the hydrolysis reaction of nitrile to generate NH₃ was accelerated. Meanwhile, the electron transfer effect from the Ag atom to Ce and hydroxyl species facilitated NH₃ desorption, which inhibited the oxidation of NH₃. Moreover, the increased surface oxygen vacancies also promoted the mineralization of hydrolysis carbonaceous intermediates to CO₂. In contrast, the Ag nanoparticle-modified sample possessed stronger reducibility and NH₃ adsorption, leading to the excessive oxidation of NH₃ to N₂ and NO. This work provided a useful guidance for resourceful purification of nitrile waste gas.