Mg and Al substituted cobalt spinels as catalysts for low temperature deN2O—Evidence for octahedral cobalt active sites

Stelmachowski, Paweł; Maniak, Gabriela; Kaczmarczyk, Jan; Zasada, Filip; Piskorz, Witold; Kotarba, Andrzej; Sojka, Zbigniew

doi:10.1016/j.apcatb.2013.05.027

Cited by 103 publications

(81 citation statements)

References 41 publications

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“…2 correspond to the E g , 3F 2g and A 1g vibration modes of the crystalline Co 3 O 4 (m 1 = 198 (F 2g ), m 2 = 486 (E g ), m 3 = 525 (F 2g ), m 4 = 624 (F 2g ), m 5 = 695 cm -1 (A 1g )), as discussed in more detail elsewhere [44,45]. The structural changes of the spinel structure would manifest in an increased asymmetry of the A 1g band as evidenced for Mg and Al substituted Co 3 O 4 [28]. This was not observed, so an excitation wavelength of Top Catal (2017) 60:333-341 335 514 nm was also used.…”

Section: Resultsmentioning

confidence: 99%

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The Effect of the Preparation Method of Pd-Doped Cobalt Spinel on the Catalytic Activity in Methane Oxidation Under Lean Fuel Conditions

et al. 2016

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In this work a series of cobalt spinel catalysts was synthesized by different methods and doped with 1 wt% of palladium via incipient wetness impregnation or solution combustion synthesis (SCS). Both undoped and Pd-doped spinels were characterized from the structural and surface point of view (XRD, XRF, lRS, BET, FESEM) and tested toward the oxidation of methane in lean conditions, in gas mixtures containing from 0.5 to 2 vol% of CH 4 . These methane concentrations are typical of processes involving combustion of CH 4 in lean conditions as the after-treatment of unconverted CH 4 in compressed natural gas-fed vehicle exhausts, or the treatment of fugitive CH 4 from leaks in coal mines. The temperature window for the catalytic activity of the undoped Co 3 O 4 materials spread from 350 to 600°C. The preparation method affected the catalytic activity of undoped Co 3 O 4 , with the best catalytic activity related to the spinel prepared by SCS employing urea. The addition of 1 wt% of Pd lowered the temperature window for the catalytic activity to the range of 250-500°C, with insignificant differences for the various preparation methods. The beneficial effect of Pd-doping was assigned to the enhancement of the reduction of cobalt in the oxide structure.

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Section: Resultsmentioning

confidence: 99%

“…In particular, among non-noble oxides in recent years cobalt oxides attracted great attention thanks to their catalytic properties, useful in many different applications, for example as magnetic materials [21,22], electrochemical devices [23,24], and various catalytic systems [25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

The Effect of the Preparation Method of Pd-Doped Cobalt Spinel on the Catalytic Activity in Methane Oxidation Under Lean Fuel Conditions

et al. 2016

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“…As discussed therein, the alkali metals of low ionization potential (IP Cs = 3.89 eV; IP K = 4.34 eV) strongly modify the surface electronic properties of the catalyst. At low surface loadings, the deposited alkali form diffuse surface dipoles (Cs [27]. However, when alkali surface coverage increases (alkali dipoles come closer) the beneficial effect of surface dipoles is ceasing due to the depolarization effect [28].…”

Section: Resultsmentioning

confidence: 99%

Optimization of cesium and potassium promoter loading in alkali-doped Zn0.4Co2.6O4|Al2O3 catalysts for N2O abatement

Ciura

Grzybek

Wojcik

et al. 2017

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A series of potassium or cesium doped Zn 0.4 Co 2.6 O 4 |Al 2 O 3 catalysts with different alkali loadings were prepared, characterized with respect to chemical composition (XRF), structure (XRD, RS) morphology (TEM), and the alkali promoter thermal stability. A strong beneficial effect on the deN 2 O activity of the Zn 0.4 Co 2.6 O 4 |Al 2 O 3 catalyst (decrease in the T 50% by about 80°C) was observed for both promoters at different surface coverages. It was found that in comparison to a rather narrow range of optimal cesium loading (0.5-2 atoms/nm 2 ) a comparable promotional effect of potassium doping was observed for a slightly wider surface concentrations (0.5-3 atoms/nm 2 ). Such difference was attributed to surface dispersion of potassium over the alumina support and the spinel active phase, while cesium was found to be located mainly on the spinel phase. For practical applications, the superiority of potassium over cesium consist in fact that a similar beneficial effect is associated with much higher thermal stability in the temperature range of the catalyst deN 2 O operation and lower price of the promoter precursor.

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“…One of the simple promising generic systems exhibiting high catalytic activity in this reaction is cobalt spinel [16,17,18,19,20], which can be additionally modified by structural [21,22,23,24] and surface donation [24,25,26,27,28] …”

Section: Introductionmentioning

confidence: 99%

Strong dispersion effect of cobalt spinel active phase spread over ceria for catalytic N2O decomposition: The role of the interface periphery

Grzybek

Stelmachowski

Gudyka

et al. 2016

Applied Catalysis B: Environmental

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dispersion effect of cobalt spinel active phase spread over ceria for catalytic N2O decomposition: the role of the interface periphery, Applied Catalysis B, Environmental http://dx.doi.org/10. 1016/j.apcatb.2015.07.027 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The catalytic tests in deN 2 O reaction revealed that the 10 wt.% of cobalt spinel in supported system is able to reproduce the activity of bare Co 3 O 4 catalyst. However, it was found that the catalyst with the lowest content of Co 3 O 4 equal to 1 wt.% exhibits the highest apparent reaction rate per mass of the spinel active phase. The observed activity was explained basing on the transmission electron microscopy analysis in terms of the dispersion of spinel phase over ceria support. A simple model that accounts for the observed strong dispersion effect is proposed. It consists in a two-step mechanism, where N 2 O is dissociated on the spinel nanograins and the resultant oxygen species are preferentially recombined at the Co 3 O 4 /CeO 2 interface periphery.

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Mg and Al substituted cobalt spinels as catalysts for low temperature deN2O—Evidence for octahedral cobalt active sites

Cited by 103 publications

References 41 publications

The Effect of the Preparation Method of Pd-Doped Cobalt Spinel on the Catalytic Activity in Methane Oxidation Under Lean Fuel Conditions

The Effect of the Preparation Method of Pd-Doped Cobalt Spinel on the Catalytic Activity in Methane Oxidation Under Lean Fuel Conditions

Optimization of cesium and potassium promoter loading in alkali-doped Zn0.4Co2.6O4|Al2O3 catalysts for N2O abatement

Strong dispersion effect of cobalt spinel active phase spread over ceria for catalytic N2O decomposition: The role of the interface periphery

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