Effect of preparation method on catalytic properties of Co-Mn-Al mixed oxides for N2O decomposition

Klyushina, Anna; Pacultová, Kateřina; Karásková, Kateřina; Jirátová, Květa; Ritz, Michal; Fridrichová, Dagmar; Volodarskaja, Anastasia; Obalová, Lucie

doi:10.1016/j.molcata.2016.10.014

Cited by 33 publications

(26 citation statements)

References 43 publications

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“…The catalytic bed contained 10 mL of the sample and the total flow rate was 500 mL min −1 (293 K, 101 325 Pa) leading to GHSV = 3000 h −1 . In both reactors, the absence of external diffusion limitation and axial dispersion was confirmed previously , .…”

Section: Methodssupporting

confidence: 93%

Cobalt Oxide Catalysts on Commercial Supports for N₂O Decomposition

et al. 2017

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Co3O4 oxide catalysts prepared on different commercial supports, namely, TiO2, Al2O3, and Mg‐Al mixed oxides with various Mg and Al concentrations, were characterized by atomic absorption spectrometry, Brunauer‐Emmett‐Teller method, X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and H2 temperature‐programmed reduction, tested for N2O decomposition, and compared with bulk Co3O4. In spite of the fact that Co3O4/70Mg30Al also contained hardly reducible compounds, it possessed the highest catalytic activity, probably due to the presence of active sites with easier reducibility and better dispersion of the active phase on the support contributing to a higher number of active sites. The conversion over Co3O4‐supported tablets is comparable with that of the same catalyst bed of bulk Co3O4 tableted catalyst.

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Section: Methodssupporting

confidence: 93%

Cobalt Oxide Catalysts on Commercial Supports for N₂O Decomposition

et al. 2017

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“…Our previous work proved a direct relationship between the crystallite size and reducibility of Co and Mn in their higher oxidation states (Co 3+ , Mn 4+ ) in Co 4 MnAlO x [17]. Taking into account that the slowest step of N 2 O decomposition is the desorption of oxygen from the catalyst surface connected to the reduction of active sites, worse reducibility of Co 3+ and probably even Mn 4+ (corresponding to the temperature maxima of the 1st reduction peak in TPR-H 2 ) causes a decrease in N 2 O conversion.…”

mentioning

confidence: 71%

“…Here the characterizatio differ more significantly, which is reflected by the differences in conversion and kinetic values determined in the kinetic regime (Table 1, Figure 3). • While the commercially prepared Cs/Co4MnAlOx has the same chemical and phase com as the laboratory prepared sample, its crystallite size is 1.8× higher than for the la prepared sample, which leads to both lower specific surface area and worse reducibi previous work proved a direct relationship between the crystallite size and reducibil and Mn in their higher oxidation states (Co 3+ , Mn 4+ ) in Co4MnAlOx [17]. Taking into acc the slowest step of N2O decomposition is the desorption of oxygen from the catalys connected to the reduction of active sites, worse reducibility of Co 3+ and probably e (corresponding to the temperature maxima of the 1 st reduction peak in TPR-H2) causes a in N2O conversion.…”

Section: Discussionmentioning

confidence: 93%

“…Both reduction peaks consist of overlapping peaks corresponding to the reduction of more species. The low-temperature reduction peak also represents, besides the reduction of cobalt species in a segregated Co3O4-like phase, the reduction of Mn IV to Mn III oxides, while Mn III → Mn II reduction can take place in both temperature regions [17]. The high temperature peak was attributed to the reduction of Co and Mn ions surrounded by Al ions in the spinel-like phase [8].…”

Section: Physicochemical Properties Of Catalystsmentioning

confidence: 97%

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Must the Best Laboratory Prepared Catalyst Also Be the Best in an Operational Application?

et al. 2019

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Three cobalt mixed oxide deN2O catalysts, with optimal content of alkali metals (K, Cs), were prepared on a large scale, shaped into tablets, and tested in a pilot plant reactor connected to the bypassed tail gas from the nitric production plant, downstream from the selective catalytic reduction of NOx by ammonia (SCR NOx/NH3) catalyst. High efficiency in N2O removal (N2O conversion of 75–90% at 450 °C, VHSV = 11,000 m3 mbed−3 h−1) was achieved. However, a different activity order of the commercially prepared catalyst tablets compared to the laboratory prepared catalyst grains was observed. Catalytic experiments in the kinetic regime using laboratory and commercial prepared catalysts and characterization methods (XRD, TPR-H2, physisorption, and chemical analysis) were utilized to explain this phenomenon. Experimentally determined internal effectiveness factors and their general dependency on kinetic constants were evaluated to discuss the relationship between the catalyst activity in the kinetic regime and the internal diffusion limitation in catalyst tablets as well as their morphology. The theoretical N2O conversion as a function of the intrinsic kinetic constants and diffusion rate, expressed as effective diffusion coefficients, was evaluated to estimate the final catalyst performance on a large scale and to answer the question of the above article title.

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“…The so-called mixed catalysts are often produced by thermal decomposition of mixed components of transition metals [3][4] . The thermal treatment of mixed solids may also lead to the formation of new compounds as a result of solid-solid interaction between the thermal products [5][6].…”

Section: Introductionmentioning

confidence: 99%

Characterization and catalytic properties of a series of CuO-MoO3 mixed oxides

Shaheen¹,

Selim²

2017

Egypt. J. Chem.

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A SERIES of single and mixed oxides of CuO-MoO 3 system were prepared by thermal treatment of pure and mixed basic copper carbonate and ammonium molybdate tetrahydrate solids. The thermal behavior of the pure and binary salts has been studied using thermal analysis (TG-DTA) technique. The thermal products were characterized using the X-ray diffraction analysis. The results revealed that, pure solids decomposed to CuO, MoO 3 and Cu 2 O phases at 250, 340 and 1000 o C respectively. Solid-solid interaction takes place between single oxides forming different phases of copper molybdate depending on treatment temperature and mixture composition. The degree of cystallinty of detected phases affected by calcination temperature solids and composition. The catalytic activity of single and binary oxides was tested in decomposition of hydrogen peroxide as a model reaction. The catalytic activity of mixed oxides was found to be higher than that of single oxides at different treatment temperature. The mechanism of decomposition reaction over the prepared oxides was discussed.

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Effect of preparation method on catalytic properties of Co-Mn-Al mixed oxides for N2O decomposition

Cited by 33 publications

References 43 publications

Cobalt Oxide Catalysts on Commercial Supports for N₂O Decomposition

Cobalt Oxide Catalysts on Commercial Supports for N₂O Decomposition

Must the Best Laboratory Prepared Catalyst Also Be the Best in an Operational Application?

Characterization and catalytic properties of a series of CuO-MoO3 mixed oxides

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Effect of preparation method on catalytic properties of Co-Mn-Al mixed oxides for N2O decomposition

Cited by 33 publications

References 43 publications

Cobalt Oxide Catalysts on Commercial Supports for N2O Decomposition

Cobalt Oxide Catalysts on Commercial Supports for N2O Decomposition

Must the Best Laboratory Prepared Catalyst Also Be the Best in an Operational Application?

Characterization and catalytic properties of a series of CuO-MoO3 mixed oxides

Contact Info

Product

Resources

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Cobalt Oxide Catalysts on Commercial Supports for N₂O Decomposition

Cobalt Oxide Catalysts on Commercial Supports for N₂O Decomposition