Preparation of Al2O3/Al monoliths by anodisation of aluminium as structured catalytic supports

Burgos, N.; Paulis, Marı́a; Montes, Mario

doi:10.1039/b212242a

Cited by 58 publications

(67 citation statements)

References 51 publications

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“…Similarly, the preparation procedure, coating thickness and adhesion of the alumina layer play a significant role for monoliths. Successes in coating methods, such as oxidation of bulk aluminium [110], slurry coating [111], chemical vapour deposition [112] and anodization of aluminium [113,114], have been reported. Slurry coating may be simpler and cost effective.…”

Section: Coating Alumina On a Metallic Surfacementioning

confidence: 99%

Monoliths: A Review of the Basics, Preparation Methods and Their Relevance to Oxidation

2017

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Considerable research has been conducted on monolithic catalysts for various applications. Strategies toward coating monoliths are of equal interest and importance. In this paper, the preparation of monoliths and monolithic catalysts have been summarized. More specifically, a brief explanation for the manufacturing of ceramic and metallic monoliths has been provided. Also, different methods for coating γ-alumina, as a secondary support, are included. Techniques used to deposit metal-based species, zeolites and carbon onto monoliths are discussed. Furthermore, monoliths extruded with metal oxides, zeolites and carbon are described. The main foci are on the reasoning and understanding behind the preparation of monolithic catalysts. Ideas and concerns are also contributed to encourage better approaches when designing these catalysts. More importantly, the relevance of monolithic structures to reactions, such as the selective oxidation of alkanes, catalytic combustion for power generation and the preferential oxidation of carbon monoxide, has been described.

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Section: Coating Alumina On a Metallic Surfacementioning

confidence: 99%

Monoliths: A Review of the Basics, Preparation Methods and Their Relevance to Oxidation

2017

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“…Thus, Mardilovich [8] showed that several phases could coexist, at a same temperature in the case of oxalic anodic films. Burgos [9] also revealed that the crystallisation temperatures of the γ and α phases are identical for oxalic and sulfuric anodic films. Furthermore, the metastable phases could be rehydrated although the transformation into α-alumina is irreversible.…”

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confidence: 93%

Chemical composition and structural changes of porous templates obtained by anodising aluminium in phosphoric acid electrolyte

Coz

Arurault

Fontorbes

et al. 2010

Surface & Interface Analysis

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Ordered anodic aluminium oxide (AAO) films were first prepared by anodising in a phosphoric acid electrolyte and then studied extensively and characterised by field emission gun-scanning electron microscopy (FEG-SEM), X-ray diffraction, Raman and infrared spectroscopy at a macroscopic scale. These analyses showed that the as-prepared AAO film is in fact amorphous, partially hydrated and that its initial global chemical composition can be described, in agreement with previous works, as: Al 2 O 3 , 0.186AlPO 4 · 0.005H 2 O. Additional analyses (thermogravimetric analysis, differential thermal analysis and FEG-SEM) showed geometrical changes of the film structure at different scales, explained by various steps of dehydration and allotropic transformations of the resulting crystallised alumina. However, because their structure remains unchanged up to 900• C, the phosphoric templates appear to be particularly suitable for applications or processes at medium or high temperatures, such as the preparation of carbon nanotubes or oxide rods. Copyright c 2010 John Wiley & Sons, Ltd.Keywords: anodic aluminium film; anodising; porous template; chemical characterisation; thermal stability IntroductionThe porous anodising of aluminium is a well-established process, widely used in various industrial applications. About 20 years ago, there was an academic renewal of interest in this process due to the possibility of experimentally observing the porosity inside the anodic film using microscopic techniques [field emission gunscanning electron microscopy (FEG-SEM), transmission electron microscope (TEM) or atomic force microscopy (AFM)]. In the following research the ability to control and optimise the mesoor nanoporosity was at stake; the pioneering research works of Masuda [1] and Gösele [2] showed that, under particular anodising conditions, it is possible to obtain porous anodic aluminium oxide (AAO) templates.Despite many previous studies, [3 -5] some aspects of anodising still remain to be clarified. Thus the chemical composition of the anodic films is open to discussion because it depends on many of the operational parameters of anodising. For example, previous works have shown that the chemical composition of the anodic films depends especially on the anodising electrolyte, as well as on the electrical conditions applied during the anodising.Many authors consider that the anodic films obtained on aluminium substrates are made of alumina (Al 2 O 3 ) and are consequently pure insulators. However, previous studies [6,7] revealed that the anodic films in fact act as n-type semiconductors. This electrical behaviour was explained by the formation of different types of aluminium oxy-hydroxides such as hydroxyl Al(OH) 3 , oxy-hydroxyl AlOOH or hydrated oxides Al 2 O 3 · xH 2 O during the anodising process. [5,6,8 -15] The crystallised phases of alumina (Al 2 O 3 ), i.e. the metastable (δ, η, θ , γ , κ, χ , ξ , etc.) or stable (α) allotropic forms, are in fact obtained only after additional thermal treatments. Thus, Mardilovich ...

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“…We have recently developed a new type of alumina/ aluminum monoliths by anodic oxidation of aluminum that is very useful for VOCs abatement [3,4]. Nevertheless, the alumina coating of these monoliths is very sensitive to the impregnation in aqueous medium because it can produce the pore sealing of the alumina coating [5].…”

Section: Introductionmentioning

confidence: 99%

New redox deposition-precipitation method for preparation of supported manganese oxide catalysts

et al. 2005

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A new preparation method has been developed to produce homogeneous coatings of manganese compounds on alumina-coated monoliths by redox deposition-precipitation using acetone as solvent. The deposition is produced by reduction of manganese permanganate with ethanol. The Lewis acid sites on the alumina catalyze this reaction. Thus, the precipitation is produced preferentially on the surface of the monolith and not in the bulk of the solution. Monoliths prepared by this method are very active for the complete oxidation of oxygenated volatile organic compounds (VOCs). These monoliths consist of a mixture of complex phases including aluminum, sulfated alumina, potassium sulfate and manganese oxide.

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Preparation of Al2O3/Al monoliths by anodisation of aluminium as structured catalytic supports

Cited by 58 publications

References 51 publications

Monoliths: A Review of the Basics, Preparation Methods and Their Relevance to Oxidation

Monoliths: A Review of the Basics, Preparation Methods and Their Relevance to Oxidation

Chemical composition and structural changes of porous templates obtained by anodising aluminium in phosphoric acid electrolyte

New redox deposition-precipitation method for preparation of supported manganese oxide catalysts

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