Re-investigating the CO oxidation mechanism over unsupported MnO, Mn2O3 and MnO2 catalysts

Ramesh, K.; Chen, Luwei; Chen, Fengxi; Liu, Yan; Wang, Zhan; Han, Yi‐Fan

doi:10.1016/j.cattod.2007.10.061

Cited by 358 publications

(185 citation statements)

References 27 publications

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“…This matches well with the results obtained for the Mn/alumina samples. The characteristic green colour of MnO was observed after the TPR experiments confirming the presence of this oxide, as reported in other works (Ferrandon et al 1999;Stobbe et al 1999;Arena et al 2001;Ramesh et al 2008;Carabineiro et al 2010a). …”

Section: Temperature Programmed Reductionsupporting

confidence: 89%

“…The TPR profile for samples doped with Mn showed two peaks (Table 2). According to what was seen in previous works (Hoflund et al 1995;Ferrandon et al 1999;Stobbe et al 1999;Arena et al 2001;PalDey et al 2005;Xu et al 2006;Ramesh et al 2008;Liang et al 2008;Wang et al 2008Wang et al , 2009Carabineiro et al 2010a), the reduction of MnO 2 to Mn 3 O 4 generates a peak at *350°C, whereas reduction of Mn 3 O 4 to MnO produces a peak at *450°C, sometimes with some overlapping between the two. This matches well with the results obtained for the Mn/alumina samples.…”

Section: Temperature Programmed Reductionsupporting

confidence: 58%

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Gold on oxide-doped alumina supports as catalysts for CO oxidation

2011

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The effect of doping a commercial alumina support with metal oxides of Ce, Co, Cu, Fe, La, Mg, Mn, Ni and Zn was investigated. Doped d-Al 2 O 3 samples were obtained by simple physical mixture (PM) of the alumina with the desired commercial oxide and by traditional impregnation of alumina with precursor salts of the same metals followed by calcination (IC). The metal load (7% wt.) was the same in both cases. Gold (1% wt.) was loaded using a liquid phase reductive deposition method. The obtained materials were characterized by adsorption of N 2 at -196°C, temperature programmed reduction, X-ray diffraction, energy-dispersive X-ray spectrometry and transmission electron microscopy. Both samples prepared by PM and IC showed a mixture of the d-alumina phase with the respective metal oxide, but the BET surface areas of the IC samples were, in general, higher than those of the PM materials. The particle size of the oxide phases were larger for the PM samples than for the IC materials. Nevertheless, catalytic experiments for CO oxidation showed that PM samples were much more active than IC. That could be explained by the size of gold nanoparticles, well known to be related with catalytic activity, that was lower in samples prepared by PM (7-16 nm) than by IC (11-17 nm). Gold was found to be in the metallic state. The most active samples were aluminas containing Zn and Fe prepared by PM that had the smallest gold nanoparticles sizes (7-13 and 8-12 nm, respectively) and had room temperature activities for CO conversion of 0.62 and 1.34 mol CO h -1 g Au -1 , respectively, which are larger than those found in the literature for doped c-alumina samples.

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Section: Temperature Programmed Reductionsupporting

confidence: 89%

Section: Temperature Programmed Reductionsupporting

confidence: 58%

Gold on oxide-doped alumina supports as catalysts for CO oxidation

2011

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“…It can be seen that the binding energy (BE) peaks of Mn 2p 3/2 for CuO/CeO 2 -MnO x (DP) and CuO/MnO x are both centered at 641.8 eV, indicting the similar state of manganese species in the two samples, and that for CuO/CeO 2 -MnO x (CB) shifts to higher binding energy centered at 642.0 eV. According to the literature 19 , the BE of Mn2p 3/2 in pure manganese oxides was found to be at 641. Fig.4 (b).…”

Section: Study Of Xps Spectra Of the Catalystsmentioning

confidence: 76%

EFFECT OF PREPARATION METHODS OF CeO2-MnOx MIXED OXIDES ON PREFERENTIAL OXIDATION OF CO IN H2-RICH GASES OVER CuO-BASED CATALYSTS

Gong

Wang

Zhang

2012

J. Chil. Chem. Soc.

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The CeO 2 -MnO x mixed oxides were prepared by deposition-precipitation (DP) and surfactant-templated (CB) methods, and then used as the support of CuO/ CeO 2 -MnO x catalysts. The samples were characterized by means of XRD, BET, H 2 -TPR, CO-TPD and XPS. Results show that preparation methods of CeO 2 -MnO x support have a direct effect on the physicochemical properties and catalytic activities of CuO/CeO 2 -MnO x catalysts for the CO preferential oxidation in H 2 -rich gases(CO PROX). CuO/CeO 2 -MnO x (CB) catalyst exhibits higher CO conversion and stability in H 2 -rich gases than CuO/CeO 2 -MnO x (DP), with 100% conversion of CO at 140 °C after a temperature cycle, which indicates that CeO 2 -MnO x (CB) as support of CuO based catalyst is more useful for CO PROX reaction than CeO 2 -MnO x (DP). Compared with CuO/CeO 2 -MnO x (DP), there are richer oxygen vacancies and more Mn 4+ species on the surface of CuO/CeO 2 -MnO x (CB), and stronger interaction between CeO 2 and MnO x in it. More amounts of active copper species and complicated transfer of electrons density on CuO/CeO 2 -MnO x (CB) also favour the activity of the catalyst.

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“…Fig. 9 illustrates the possible mechanism of this catalytic reaction by the Mars-van Krevelen process in detail [29][30][31][32]. This process begins with the diffusion and adsorption of benzyl alcohol at the Lewis acid sites (Mn 4+ Finally, using δ-MnO 2 as the catalyst, several derivatives of benzyl alcohol and 4-pyridylcarbinol were subjected to the oxidation reaction to further examine its catalytic performance.…”

Section: Science China Materialsmentioning

confidence: 99%

Crystalline-phase-dependent catalytic performance of MnO2 for aerobic oxidation reactions

Huang

Yang

et al. 2017

Sci. China Mater.

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Knowledge of the catalytic performances of different crystalline phases of a material is vital for the development of superior catalysts. In this study, different phases of MnO 2 (α, β, γ, and δ) have been prepared by the oxidation of Mn 2+, and their catalytic performances were evaluated using the aerobic oxidation of benzyl alcohol to benzaldehyde as a model reaction. α-MnO 2 promoted the reaction to the highest yield. However, when the yields were normalized by the corresponding surface areas, δ-MnO 2 exhibited the highest specific activity and α-MnO 2 the lowest, indicating that the diverse microstructures resulting from the crystalline phase have a profound effect on catalytic performance. α-MnO 2 showed the highest catalytic stability, resulting from its unchanged composition and morphology after use. Informed by the experimental results, a possible reaction mechanism involving the Mars-van Krevelen process was proposed. This work provides useful information for the development of effective catalysts for aerobic oxidation.

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Re-investigating the CO oxidation mechanism over unsupported MnO, Mn2O3 and MnO2 catalysts

Cited by 358 publications

References 27 publications

Gold on oxide-doped alumina supports as catalysts for CO oxidation

Gold on oxide-doped alumina supports as catalysts for CO oxidation

EFFECT OF PREPARATION METHODS OF CeO2-MnOx MIXED OXIDES ON PREFERENTIAL OXIDATION OF CO IN H2-RICH GASES OVER CuO-BASED CATALYSTS

Crystalline-phase-dependent catalytic performance of MnO2 for aerobic oxidation reactions

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