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

Abstract

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 NH 3 generation simultaneously. The developed silver single-atom-doped ceria nanorod (Ag 1 /R-CeO 2 ) was endowed with near complete mineralization and around 90% NH 3 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 NH 3 was accelerated. Meanwhile, the electron transfer effect from the Ag atom to Ce and hydroxyl species facilitated NH 3 desorption, which inhibited the oxidation of NH 3 . Moreover, the increased surface oxygen vacancies also promoted the mineralization of hydrolysis carbonaceous intermediates to CO 2 . In contrast, the Ag nanoparticle-modified sample possessed stronger reducibility and NH 3 adsorption, leading to the excessive oxidation of NH 3 to N 2 and NO x . This work provided a useful guidance for resourceful purification of nitrile waste gas.