Recent Advances on Nitrous Oxide (N2O) Decomposition over Non-Noble-Metal Oxide Catalysts: Catalytic Performance, Mechanistic Considerations, and Surface Chemistry Aspects

Nitrous oxide (N2O) is the largest stratospheric-ozone-depleting substance, being concomitantly the third most potent greenhouse gas. The direct catalytic decomposition of N2O (deN2O process) is one of the most promising remediation technologies for N2O emissions abatement. Although noble metals (NMs)-based catalysts demonstrate satisfactory deN2O performance, their high cost and sensitivity to various effluent stream components (e.g., water vapor, oxygen) limit their widespread industrial applications. Hence, the development of NMs-free catalysts of low cost and satisfactory deN2O performance is of paramount importance. This survey appraises the recent advances, which have been reported since 2000, on N2O decomposition over non-noble-metal oxidic catalysts. Initially, a brief overview of N2O sources, environmental consequences, and remediation technologies is provided. The literature related to the deN2O process over NMs-free metal oxides (MOs) is categorized and critically discussed, as follows: (i) bare oxides, (ii) hexaaluminates, (iii) hydrotalcites, (iv) spinels, (v) perovskites, and (iv) mixed metal oxides not belonging in the above categories. This review covers several aspects with respect to the reaction mechanisms, the structure–activity correlations, the role of various inhibitors (e.g., O2, NO, H2O) as well as the strategies followed to adjust the local surface structure of MOs. Fundamental insights toward fine-tuning of surface chemistry of MOs by means of advanced preparation routes and/or electronic promotion are also provided, paving the way for real-life energy and environmental applications, beyond the deN2O process.