Anthropogenic activities represent the dominant source of several environmentally harmful gaseous pollutants, including nitrous oxide (N₂O), nitrogen monoxide (NO), carbon monoxide (CO), and volatile organic compounds (VOCs). N₂O is predominantly emitted during nitric acid production, which serves as a key precursor for fertilizers and explosives, while NO is generated during high-temperature combustion processes in the energy sector, industry, and automotive transport. In contrast, CO and light hydrocarbons such as propane and methane are mainly released during incomplete combustion of biomass, particularly in domestic heating appliances. These pollutants negatively affect human health and contribute to environmental issues such as air quality deterioration, climate change, and photochemical smog formation.
Various mitigation technologies have been developed to reduce emissions of these compounds [1]; however, many of the currently applied catalytic systems rely on noble metals or metal oxides that are either costly or insufficiently environmentally friendly. Consequently, significant research efforts are focused on the development of alternative catalytic materials based on earth-abundant transition metals [2, 3].
In this work, Co-based mixed metal oxides (MMOs) were investigated as multifunctional catalysts for three environmentally relevant reactions: N₂O decomposition, direct catalytic decomposition of NO, and oxidation of CO, propane, and methane. A wide range of Co-based MMO systems was tested, demonstrating promising catalytic performance across all studied reactions. The catalysts were prepared by co-precipitation from nitrate precursors, with the addition of alkali promoters for N₂O and NO decomposition to enhance activity. For N₂O decomposition and CO/VOC oxidation, scale-up studies were conducted, including deposition of the active phase onto structured supports such as ceramic foams and ceramic monoliths.
Comprehensive physicochemical characterization was performed to identify key properties governing catalytic activity and stability. Furthermore, different preparation strategies were explored to optimize synthesis parameters and achieve highly active and stable Co-based MMO catalysts, highlighting their potential as viable alternatives to noble-metal-based systems for environmental applications.
Refferences:
[1] L. Alves, L.I.V. Holz, C. Fernandes, P. Ribeirinha, D. Mendes, D.P. Fagg, A. Mendes, A comprehensive review of NOx and N2O mitigation from industrial streams, Renewable and Sustainable Energy Reviews, 155 (2022) 111916.
[2] R. Li, Y. Li, Z. Liu, Recent advances in the catalytic removal of NOx and N2O over spinel oxide-based catalyst, Fuel, 355 (2024) 129405.
[3] Z. You, T. Liu, M. Chen, H. Chen, Co-based spinel and perovskite oxides in catalytic combustion of volatile organic compounds: Recent advances and future prospects, Journal of Environmental Chemical Engineering, 13 (2025) 115359.
Acknowledgement: This research has been produced with the financial support of the European Union under the REFRESH – Research Excellence For REgion Sustainability and High-tech Industries project number CZ.10.03.01/00/22_003/0000048 via the Operational Programme Just Transition.“ The experiments were performed using the Large Research Infrastructure ENREGAT (No. LM2023056) supported by the Ministry of Education, Youth and Sports of the Czech Republic.