Thermal solid–solid interaction and physicochemical properties of CuO–Fe2O3 system

Shaheen, W.M.; Ali, Amjad

doi:10.1016/s1466-6049(01)00165-9

Cited by 37 publications

(21 citation statements)

References 14 publications

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“…It can be reported that the percentage of CO conversion increases by time till a maximum value and then become constant owing to poisoning of catalyst. MnFe 2 O 4 samples show low response towards CO oxidation (30-40% efficiency within 10 min), while the response towards catalytic oxidation is increased with increasing Cu 2+ The variation of catalytic oxidation reactions of CO with structure changes can be explained in terms of the concept of bivalent catalytic centers theory [8]. It was found that the catalytic activity of the mixed Cu-Fe-Mn mixtures obtained by thermal treatment of the CuO-MnO 2 -Fe 2 O 3 at the same calcinations temperatures is greater than that of single crystal.…”

Section: Effect Of Structure Changes On the Catalytic Oxidation Processmentioning

confidence: 99%

“…The centers of CuO consist of Cu 2+ -Cu + ion pairs while the centers of MnO 2 contain Mn 4+ -Mn 2+ ion pairs and that of Fe 2 O 3 consist of Fe 3+ -Fe 2+ ion pairs. The higher catalytic activity of the three component oxides can be attributed to the fact that beside the one component sites Cu 2+ -Cu + , Mn 4+ -Mn 2+ and Fe 3+ -Fe 2+ there will be also the mixed sites Mn 4+ -Cu 1+ -Fe 2+ and/or Cu 2+ -Fe 3+ -Mn 2+ ion pairs as a result of mutual charge interaction [8]. In other words, increasing activity of the mixed oxides might be attributed to the increase in the concentration of active sites via creation of new ion pairs.…”

Section: Effect Of Structure Changes On the Catalytic Oxidation Processmentioning

confidence: 99%

“…Shaheen et al [8] measured the catalytic activity of the obtained pure and mixed oxides of CuO-Fe 2 O 3 for the decomposition of H 2 O 2 at 30-50°C. It was found that the mixed oxide solids have catalytic activity higher than single oxides preheated at 350 and 550°C.…”

Section: Introductionmentioning

confidence: 99%

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Catalytic Oxidation of CO Gas over Nanocrystallite Cu x Mn1−x Fe2O4

et al. 2008

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The catalytic oxidation of CO over nanocrystallite Cu x Mn (1-x) Fe 2 O 4 powders was studied using advanced quadruple mass gas analyzer system. The oxidation of CO to CO 2 was investigated as a function of reactants ratio and firing temperature of ferrite powders. The maximum CO conversion was observed for ferrite powders which have equal amount of Cu 2+ and Mn 2+ (Cu 0.5 Mn 0.5 Fe 2 O 4 ). The high catalytic activity of Cu 0.5 Mn 0.5 Fe 2 O 4 can be attributed to the changes of the valence state of catalytically active components of the ferrite powders. The firing temperature plays insignificant role in the catalytic activity of CO over nanocrystallite copper manganese ferrites. The mechanism of catalytic oxidation reactions was studied. It was found that the CO catalytic oxidation reactions on the surface of the Cu x Mn 1-x Fe 2 O 4 was done by the reduction of the ferrite by CO to the oxygen deficient lower oxide then re-oxidation of this phase to the saturated oxygen metal ferrite again.

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Section: Effect Of Structure Changes On the Catalytic Oxidation Processmentioning

confidence: 99%

Section: Effect Of Structure Changes On the Catalytic Oxidation Processmentioning

confidence: 99%

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Catalytic Oxidation of CO Gas over Nanocrystallite Cu x Mn1−x Fe2O4

et al. 2008

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“…The decomposition reactions of various compounds are of major importance because of their frequent applications in calcination in metallurgy and in the production of large-surface materials for sorbents and catalysts [1][2]. The so-called mixed catalysts are often produced by thermal decomposition of mixed components of transition metals [3][4] .…”

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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“…The binary oxide composite systems containing hematite (α-form of Fe 2 O 3 ) find applications in magnetic materials and catalysts [1][2][3]. When hematite is mixed with ceria, it densifies the ceria [4].…”

Section: Introductionmentioning

confidence: 99%

Mössbauer studies of nano phase Ce–Fe oxide composites

Pandey

Mohapatra²,

Anand³

et al. 2008

Hyperfine Interact

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Chemical co-precipitation method was used to synthesize nano-structured α-Fe 2 O 3 -CeO 2 composite by calcination of the goethite-cerium hydroxide precursor. It was observed that the precursor contained goethite matrix doped with cerium. Calcination of the precursor at 400 • C showed the formation of nanosize hematite. Mössbauer spectra show the presence of a paramagnetic component in the precursor but not in the samples calcined at 400 • C to 800 • C temperatures. Our study shows that Ce precipitated as CeO 2 and stuck on the surface of hematite particles. The precipitation of Ce as CeO 2 is independent of the concentration of Ce in the Ce-Fe-O composite.

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Thermal solid–solid interaction and physicochemical properties of CuO–Fe2O3 system

Cited by 37 publications

References 14 publications

Catalytic Oxidation of CO Gas over Nanocrystallite Cu x Mn1−x Fe2O4

Catalytic Oxidation of CO Gas over Nanocrystallite Cu x Mn1−x Fe2O4

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

Mössbauer studies of nano phase Ce–Fe oxide composites

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