Three kinds of active states existed in the MnO x-CeO 2 catalysts: (i) Mn cations in the fluorite structure, (ii) active dispersed MnO x surface particles strongly interacting with CeO 2 oxide, and (iii) relatively large MnO x aggregates on the surface of the support. applied hydrothermal synthesis combined with redox deposition. used urea combustion to prepare a Mn 0.5Ce 0.5O 2 catalyst. employed the impregnation of a MnO x-CeO 2 catalyst on Al 2O 3. For the preparation of MnO x-CeO 2 catalysts, methods such as combustion, coprecipitation, sol–gel, and template synthesis are used. Recently, the number of works devoted to Mn-Ce oxide catalysts has sharply increased special attention is paid to improving the synthesis methods leading to the formation of active, highly dispersed and nanostructured compounds. The Mn-Ce oxides show excellent catalytic performance in the oxidation of hydrocarbons, volatile organic compounds, CO and selective catalytic oxidation of NO x with NH 3.

The cooperation of manganese and cerium oxides enhances oxygen mobility and redox ability. The introduction of a redox-active cation into ceria to form a solid solution or a strong metal−support interaction changes the properties of materials. The incredible performance of ceria has been traditionally associated with the excellent ability of these oxides to shuttle between Ce(III) and Ce(IV) states, their oxygen storage capacity, and abundant oxygen vacancies. For example, CeO 2 is well known as an irreplaceable component in three-way catalysts and low-temperature selective catalytic reduction of NO x. Ĭeria (CeO 2) has inferior activity in the oxidation reactions of CO, but it has been widely applied as a catalyst support or a surface modifier.

The catalytic activity in oxidation reactions on manganese oxides is associated with their structural flexibility and variability of the oxidation state of manganese. They are an alternative to noble metal catalysts because, along with their low cost, they have thermal stability and resistance to sulfur poisoning. For these purposes, manganese-containing catalysts have received considerable attention. The elimination of CO via catalytic oxidation is one of the most effective methods for the purification of exhaust gases from automobiles and industry. In particular, emissions of carbon monoxide pose a serious threat to human health and ecology. The combustion of fossil fuels in power plants, motor vehicles, and other industries emits different toxic pollutants such as CO, NO x, and volatile organic compounds (VOCs), which are very dangerous for the environment and human health.

50 at.% Mn due to the high specific surface area, the formation of the solid solution, and the maximum content of the solid solution. The best catalytic performance was exhibited by the catalyst containing ca. The catalytic activity as a function of the manganese content had a volcano-like shape. An increase in the manganese content resulted in the formation of manganese oxides such as Mn 2O 3, Mn 3O 4, and Mn 5O 8. The introduction of manganese led to a reduction of the oxide particle size, a decrease in the surface area, and the formation of a Mn 圜e 1−yO 2−δ solid solution. The nanocrystalline oxides with a fluorite structure and particle sizes of 4–6 nm were formed. The Mn-Ce catalysts were prepared by thermal decomposition of oxalates by varying the Mn:Ce ratio. The Mn-Ce oxide catalysts active in the oxidation of CO were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), transition electron microscopy (TEM), energy dispersive X-Ray (EDX), and a differential dissolution technique.

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