Effect of metal-doping (Me = Fe, Ce, Sn) on phase composition, structural peculiarities, and CO oxidation catalytic activity of cryptomelane-type MnO2

Highly Active and Water-Resistant Cu-Doped OMS-2 Catalysts for CO Oxidation: The Importance of the OMS-2 Synthesis Method and Cu Doping

“…Analysis of the diameter and length distribution of the three OMS-2 catalysts (Figure S2) indicates that both the average diameter and the average length of OMS-2 increase in the order of OMS-2 S < OMS-2 R < OMS-2 H (Table S1), resulting from the fact that the diameter and length of OMS-2 increase with the increase of synthesis temperature, pressure, and time. 8,18,19 HRTEM characterization shows that all three of the OMS-2 catalysts display the typical facets for OMS-2 (Figure 1g−i). Compared with OMS-2 R and OMS-2 H , OMS-2 S shows more blurred lattice fringes, indicating its relatively poor crystallinity, which should be related to its lower synthesis temperature and shorter synthesis time.…”

“…SEM (Figure a–c) and TEM (Figure d–f) characterizations show that all the three OMS-2 catalysts exhibit a fibrous rod-like morphology, which is the typical morphology of the OMS-2 material, and the nanorod length of OMS-2 S (Figure a,d) is much smaller than that of OMS-2 R (Figure b,e) and OMS-2 H (Figure c,f). Analysis of the diameter and length distribution of the three OMS-2 catalysts (Figure S2) indicates that both the average diameter and the average length of OMS-2 increase in the order of OMS-2 S < OMS-2 R < OMS-2 H (Table S1), resulting from the fact that the diameter and length of OMS-2 increase with the increase of synthesis temperature, pressure, and time. ,, …”

“…While noble metals like Pd, Pt, and Au are frequently used as catalysts due to their superior performance, their scarcity and high cost have restricted their application. As a result, various low-cost transition metal oxides have gained significant attention as alternative catalysts for CO oxidation; ,,− among them, Mn-based oxides have attracted particular attention because of their low cost and relatively good CO oxidation performance. , …”

The research on CO oxidation over Ce–Mn oxides: The preparation method effects and oxidation mechanism

“…(Wang et al, 2022) The kinetics of CO oxidation on MnCeO x catalyst shows that the surface oxygen vacancies promote CO oxidation, special attention was paid to the oxide structure leading to the most active catalyst. (Arena et al, 2017) The addition of the Ce element is of great potential to change the crystal structure and valence state of MnO x , and the substitution of Ce to Mn helps to enhance the lattice oxygen activity, promoting the reactivity of CO oxidation reactions (Wei The rise in ceria concentration of Ce-Mn oxides has also been reported to have different morphology and microstructure: the nanorod particles became notably shorter and thinner, and some thick flakes or agglomerates of shapeless nanoparticles were also seen, changing the mesopore properties and specific surface area (Kharlamova et al, 2022). The Ce-Mn-O solid solution with superior catalytic activity was made using a deposition coprecipitation technique.…”

Chemical State of Potassium on the Surface of Iron Oxides: Effects of Potassium Precursor Concentration and Calcination Temperature

“…Based on recent studies, the calcination temperature may affect the catalytic activity of iron oxide-based catalysts by changing the electronic and chemical state of potassium in the vicinity of iron oxide [ 26 , 27 , 28 ]. On the other hand, the changing composition of potassium may also affect active sites on the catalyst and, thereby, the catalytic performance [ 29 , 30 , 31 ]. An iron-based catalyst was synthesized using a potassium nitrate precursor with varying potassium loading and a calcination temperature of 400 or 500 °C to study the CO 2 hydrogenation reaction [ 32 , 33 , 34 ].…”