Preparation of magnetite-based catalysts and their application in heterogeneous Fenton oxidation – A review

Muñoz, Macarena; Pedro, Zahara M. de; Casas, José A.; Rodrı́guez, Juan J.

doi:10.1016/j.apcatb.2015.04.003

Cited by 622 publications

(273 citation statements)

References 131 publications

(131 reference statements)

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“…They discuss the use of iron oxide-based catalysts in the Fenton reaction [16], ethylbenzene dehydrogenation [17], and Fischer-Tropsch synthesis [18]. It is interesting to note, however, that while iron oxides are reactive enough to catalyse certain reactions, they are often used as the inexpensive support for metal nanoparticles, and there is mounting evidence that support effects can play a significant role in such systems [19], particularly when nanoparticles enter the sub-nano regime.…”

Section: Motivationmentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

460

452

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The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe 3 O 4 ), maghemite (γ-Fe 2 O 3 ), hematite (α-Fe 2 O 3 ), and wüstite (Fe 1-x O) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe 3 O 4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment, and because it is an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed.The best understood iron oxide surface at present is probably Fe 3 O 4 (100); the structure is known with a high degree of precision and the major defects and properties are well characterised. A major factor in this is that a termination at the Fe oct -O plane can be reproducibly prepared by a variety of methods, as long as the surface is annealed in 10 Such straightforward preparation of a monophase termination is generally not the case for other iron oxide surfaces. All available evidence suggests the oft-studied (√2×√2)R45° reconstruction results from a rearrangement of the cation lattice in the outermost unit cell in which two octahedral cations are replaced by one tetrahedral interstitial, a motif conceptually similar to well-known Koch-Cohen defects in Fe (0001) is the most studied hematite surface, but 2 difficulties preparing stoichiometric surfaces under UHV conditions have hampered a definitive determination of the structure. There is evidence for at least three terminations: a bulk-like termination at the oxygen plane, a termination with half of the cation layer, and a termination with ferryl groups. When the surface is reduced the so-called "bi-phase" structure is formed, which eventually transforms to a Fe 3 O 4 (111)-like termination. The structure of the bi-phase surface is controversial; a largely accepted model of coexisting Fe 1-x O and α-Fe 2 O 3 (0001) islands was recently challenged and a new structure based on a thin film of Fe 3 O 4 (111) on α-Fe 2 O 3 (0001) was proposed. The merits of the compet...

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Section: Motivationmentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

460

452

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“…The second ongoing mechanism is the homogeneous catalysis. Dissolved in the acidic environment iron-containing minerals, released Fe 2+ ions to the solution, becomes a Fenton/pseudo-Fenton reaction activator [30].…”

Section: Polluted Soil and Flowback Fluid Treatmentmentioning

confidence: 99%

Magnetic Markers Use for Monitoring of Environmental Pollution Caused by Fracturing Fluids During Shale Gas Exploitation

Bogacki

Zawadzki

2017

ZNPRzBiS

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“…The catalysts promoted the cracking of the higher hydrocarbons into fuel oil. 31 Magnetite is commonly used as a catalyst in several reaction types, e.g., organic reactions, 32 ammonia synthesis and degradation of organic contaminants. 33 In this study we report the catalytic effects of mesoporous silica (SBA- [15][16] supported iron catalysts with the goal of upgrading the thermal decomposition products of deoiled algae and jatropha seed cakes.…”

Section: S4mentioning

confidence: 99%

Thermoanalytical Characterization and Catalytic Conversion of Deoiled Micro Algae and Jatropha Seed Cake

et al. 2016

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Abstract:The thermal decomposition of the by-products of the biodiesel process was studied by thermoanalytical methods. De-oiled algae cake and jatropha seed de-oiled cake were pyrolyzed and the catalytic effects of silica supported iron catalysts (Fe/FSM-16 and Fe/SBA-15) and magnetite (Fe 3 O 4 ) were tested. The evolution profiles of the decomposition products as well as the thermal stability of the samples were determined by thermogravimetry/mass spectrometry (TG/MS). The formation of the volatile products was monitored by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The composition and the amounts of the S2 gaseous products changed significantly in the presence of the silica supported iron catalysts: the yield of hydrogen and carbon monoxide considerably increased above the decomposition temperature of 400 °C. Both silica supported iron catalysts had important effects on the yield of the products originating from carbohydrates and lignins. The formation of anhydrosugars and phenolic compounds was hindered, while the evolution of aromatic and aliphatic hydrocarbons was enhanced. Fe/FSM-16 proved to be more efficient than Fe/SBA-15 and Fe 3 O 4 catalysts. The thermal decomposition of the protein content of the samples resulted in the formation of 2,5-diketopiperazines and smaller molecules (e.g., ammonia). The silica supported iron catalysts had a special effect: their presence promoted the reaction of fatty acid esters and ammonia resulting in the formation of alkyl nitriles during the thermal decomposition.

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Preparation of magnetite-based catalysts and their application in heterogeneous Fenton oxidation – A review

Cited by 622 publications

References 131 publications

Iron oxide surfaces

Iron oxide surfaces

Magnetic Markers Use for Monitoring of Environmental Pollution Caused by Fracturing Fluids During Shale Gas Exploitation

Thermoanalytical Characterization and Catalytic Conversion of Deoiled Micro Algae and Jatropha Seed Cake

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