Study of Cu/Mn Catalysts for Coreactions of NH3-SCR and CO Oxidation

Unveiling Trade-Off and Synergy in Simultaneous Removal of NOx, CO, and NH3 on Mixed Metal Oxide Nanostructure Catalysts

The simultaneous removal reaction (SRR) is a pioneering approach for achieving the simultaneous removal of anthropogenic NOx and CO pollutants through catalytic reactions. To facilitate this removal across diverse industrial fields, it is crucial to understand the trade-offs and synergies among the multiple reactions involved in the SRR process. In this study, we developed mixed metal oxide nanostructures derived from layered double hydroxides as catalysts for the SRR, achieving high catalytic conversions of 93.4, 100, and 91.6% for NOx, CO, and NH3, respectively, at 225 °C. Furthermore, we elucidated the reaction mechanisms, revealing the trade-offs and synergies between the multiple reactions. In addition, we fabricated sheet-type catalysts and conducted SRR tests in a semibench-scale reactor with a gas flow rate of 10 L min-1 at 1% CO concentration. The fabricated catalysts exhibited high SRR activity and stability, even in the presence of SO2, highlighting their potential for practical applications.

A Review of Mn-Based Catalysts for Abating NOx and CO in Low-Temperature Flue Gas: Performance and Mechanisms

Mn-based catalysts have attracted significant attention in the field of catalytic research, particularly in NOx catalytic reductions and CO catalytic oxidation, owing to their good catalytic activity at low temperatures. In this review, we summarize the recent progress of Mn-based catalysts for the removal of NOx and CO. The effects of crystallinity, valence states, morphology, and active component dispersion on the catalytic performance of Mn-based catalysts are thoroughly reviewed. This review delves into the reaction mechanisms of Mn-based catalysts for NOx reduction, CO oxidation, and the simultaneous removal of NOx and CO. Finally, according to the catalytic performance of Mn-based catalysts and the challenges faced, a possible perspective and direction for Mn-based catalysts for abating NOx and CO is proposed. And we expect that this review can serve as a reference for the catalytic treatment of NOx and CO in future studies and applications.

In situfabrication of Cu-Mn-O nanostructure catalysts on Ti mesh and their catalytic property optimization for low-temperature and stable CO oxidation

A series of interlaced 'tripe-shaped' nanoflake catalysts made of CuMn2O4werein situprepared on Ti mesh substrate through the associated methods of plasma electrolyte oxidation and hydrothermal technique. The surface morphology, elemental distribution and chemical state, phase composition and microstructure of CuMn2O4nanostructures prepared under different conditions were systemically investigated. To evaluate the catalytic activity, the CO oxidation as a probe reaction was used, and the results showed that 12h-Cu1Mn2-300 (hydrothermal reaction at 150 °C for 12 h, Cu/Mn = 1/2 in initial precursor, heat treatment temperature at 300 °C) exhibited the best CO oxidation capability withT100= 150 °C owe to the formation of uniform CuMn2O4nanosheet layersin situgrown on flexible Ti mesh and the synergistic effect of Cu and Mn species in spinel CuMn2O4, which makes it more active towards CO oxidation than pure copper/manganese oxides.

CO + NH3 coupling denitration at low temperatures over manganese/activated carbon catalysts

To explore the mechanism of low-temperature carbon monoxide and ammonia (CO + NH₃) coupling denitration of manganese/activated carbon (Mn/AC) catalysts, Mn/AC series catalysts were prepared using the impregnation method with AC activated by nitric acid as a precursor and manganese nitrate as a precursor. We characterized the surface morphology, pore structure, active component phase, functional group, and active component valence change law of the Mn/AC catalyst. The denitration rate order with different Mn loadings is 7Mn/AC > 9Mn/AC > 5Mn/AC. When the Mn loading was 7%, the catalyst's surface was smooth, with a good pore structure and uniform surface distribution of metal particles. These features increased the reacting gas's contact area, improving the denitration rate. The reason for this was oxygen chemisorption on the catalyst's surface. The Mn⁴⁺ and the number of oxygen-containing functional groups on the catalyst surface increase after Mn loading increases; this provides more active sites for denitration and promotes the reaction's conversion to fast selective catalytic reduction. The low-temperature CO + NH₃ coupling denitration of Mn/AC catalysts conforms to the Langmuir-Hinshelwood mechanism when the temperature is lower than 230 °C and the Eley-Rideal mechanism when the temperature is higher than 230 °C. The research results can provide new ideas for low-temperature flue gas denitration.

Interactions between CO oxidation and selective catalytic reduction of NO with NH3 over Mn-based catalysts

The α-MnO2-Cu catalyst has a high NO and CO removal rate. CO reduced the NH3-SCR activity by inhibiting NO adsorption. NH3 negatively affected CO oxidation by minimizing the formate intermediate. NO decomposed intermediates to promote CO oxidation.