Preparation, characterization, and methane total oxidation of AAl12O19 and AMAl11O19 hexaaluminate catalysts prepared with urea combustion method

Yin, Fengxiang; Ji, Shengfu; Wu, Pingyi; Zhao, Fulin; Li, Chengyue

doi:10.1016/j.molcata.2008.05.015

Cited by 37 publications

(22 citation statements)

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“…This is supported by reports that O 2À is less tightly bound in the mirror plane than in the spinel blocks. [18,[46][47][48] II) A Ni 2 + cation, substituted in the hexaaluminate structure and prevailing near the mirror plane region [18] migrates within the (0 0 1) plane up to the grain boundary. III) At the grain boundary, Ni 2 + is reduced over the outer surface of the hexaaluminate platelets.…”

Section: I)mentioning

confidence: 99%

Structure–Activity Relationships of Nickel–Hexaaluminates in Reforming Reactions Part I: Controlling Nickel Nanoparticle Growth and Phase Formation

Roussière

Schelkle

Titlbach³

et al. 2014

ChemCatChem

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Water‐in‐oil‐in‐water (W/O/W) and water‐in‐oil (W/O) emulsions of paraffin oil were prepared with sorbitan monooleate (Span 80)/polyoxyethylene sorbitan monooleate (Tween 80) or polyethylene glycol monostearate (SG‐6), respectively. The physical characteristics and the absorption of toluene gas in these emulsions were investigated to evaluate the influence of the emulsifier dosage and the oil/water ratio. Both investigated W/O/W emulsions provided high stabilities and low viscosities. The absorption of toluene gas was excellent, with little foam occurring during the absorption. Although the W/O emulsions with 2–5 % SG‐6 were of high stability, their high viscosities strongly limited their application as volatile organic compound absorbents. Stable emulsions consisted of small and uniform droplets and some emulsions underwent mild demulsification after the absorption.

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Section: I)mentioning

confidence: 99%

Structure–Activity Relationships of Nickel–Hexaaluminates in Reforming Reactions Part I: Controlling Nickel Nanoparticle Growth and Phase Formation

Roussière

Schelkle

Titlbach³

et al. 2014

ChemCatChem

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“…However, perovskites and pyrochlores and solid solution oxide catalysts suffer from gas diffusion limitation in combustion due to their low specific surface areas (SSAs) [15,[17][18][19]24]. The activity of most hexaaluminates is very low for igniting methane combustion and these are difficult to synthesize [7,10,[20][21][22]. Most recently, transition metal composite oxides derived from hydrotalcites have shown great potential as novel combustion catalysts due to their excellent catalytic activity and stability, high SSAs and dispersion of active sites [26][27][28].…”

mentioning

confidence: 99%

“…In addition, catalytic combustion of lean methane gas to abate methane emission also has wide-ranging applications [5,7]. For the effective and stable catalytic combustion process, suitable catalysts play a crucial role.…”

mentioning

confidence: 99%

“…Generally, supported noble metal oxides, particularly palladium oxide, are excellent catalysts for lower temperature combustion, but noble metals are expensive and prone to deactivation owing to sintering, decomposition and undesirable interaction with supports under hydrothermal situations encountered in combustion [3,6,[8][9][10]. A variety of inexpensive transition metal oxide catalysts, such as solid solution oxides [11][12][13], perovskites [14][15][16], pyrochlores [17][18][19] and hexaaluminates [7,[20][21][22] have been explored for catalytic combustion of methane. Unfortunately, no single catalyst, so far, can tolerate the stringent hydrothermal conditions existing in methane combustion.…”

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confidence: 99%

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Catalytic combustion of methane over mixed oxides derived from Co–Mg/Al ternary hydrotalcites

Jiang

Cheng

et al. 2010

Fuel Processing Technology

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Co x Mg 3 − x /Al composite oxides (xCoMAO-800) were prepared by calcination of Co x Mg 3 − x /Al hydrotalcites (x = 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, respectively) at 800°C. The materials were characterized using XRD, TG-DSC, N 2 adsorption-desorption and TPR. The methane catalytic combustion over the xCoMAO-800 was assessed in a fixed bed micro-reactor. The results revealed that cobalt can be homogenously dispersed into the matrices of the hydrotalcites and determines the structure, specific surface areas and porosity of the derived xCoMAO-800 oxide catalysts. The thermal stability and homogeneity of the hydrotalcites markedly depends on the cobalt concentration in the hydrotalcites. The Co-based hydrotalcite-derived oxides exhibit good activity in the catalytic combustion of methane. The catalytic activity over the xCoMAO-800 oxides enhances with increasing x up to 1.5, but subsequently decreases dramatically as cobalt loadings are further increased. The 1.5CoMAO-800 catalyst shows the best methane combustion activity, igniting methane at 450°C and completing methane combustion around 600°C. The catalytic combustion activity over the xCoMAO-800 oxides are closely related to the strong Co-Mg/Al interaction within the mixed oxides according to the TG-DSC, TPR and activity characteristics.© 2009 Elsevier B.V. All rights reserved.The catalytic combustion of methane has attracted intensive interests in the past few decades, due to its higher energy conversion efficiency and ultra-low emissions of environmental pollutants, such as NO x , CO, and unburned hydrocarbons [1][2][3][4][5][6]. In addition, catalytic combustion of lean methane gas to abate methane emission also has wide-ranging applications [5,7]. For the effective and stable catalytic combustion process, suitable catalysts play a crucial role. Generally, supported noble metal oxides, particularly palladium oxide, are excellent catalysts for lower temperature combustion, but noble metals are expensive and prone to deactivation owing to sintering, decomposition and undesirable interaction with supports under hydrothermal situations encountered in combustion [3,6,[8][9][10]. A variety of inexpensive transition metal oxide catalysts, such as solid solution oxides [11][12][13], perovskites [14][15][16], pyrochlores [17][18][19] and hexaaluminates [7,[20][21][22] have been explored for catalytic combustion of methane. Unfortunately, no single catalyst, so far, can tolerate the stringent hydrothermal conditions existing in methane combustion. Obviously, the further development of new combustion catalysts is indispensable. Currently, multi-staged combustion methodology are used to overcome the drawbacks of the current catalysts for catalytic combustion [2,3], in which the catalysts of high surface area and activity are highly desired to ignite methane at lower temperatures and sustain stable combustion at high temperatures.Among the transition metal oxide catalysts, cobalt-based oxides are ones of the most active catalysts in catalytic methane combustion, and Co...

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“…One the most promising hightemperature materials are hexaaluminates. They are compounds with the general structure of A 2+ B 12 3+ O 19 [1], and they contain alkali, alkaline earth or rare earth metal, with Beta -Al 2 O 3 or magnetoplumbite -type crystal structure [2].This class of hexaaluminates, has been utilized as a material for thermal barrier coatings (TBCs) [3]. Typically, thermal barrier coatings are composed of two important layers; the first one is a porous, insulating ceramic oxide top layer of yttria-stabilized with zirconia (YSZ), which provides thermal protection.…”

Section: Introductionmentioning

confidence: 99%

A Novel Technique for Synthesis A Thermal Barrier Coating Material of Lanthanum -Magnesium Hexaaluminate (LaMgAlllO19)

Mohsen¹

2014

IJIRSET

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ABSTRACT:As the advances in some industrial applications are leading to higher operating temperatures; materials of metallic coatings that withstand harsh environments at high temperature are developing. One of the most promising compounds, which can be used as a material for thermal barrier coatings (TBCs) is lanthanum magnesium hexaaluminate (LaMgAl l1 O 19 ).The objective of this study, was to synthesize LaMgAl ll O 19 through a technique of tartaric acid precursor. Effect of different annealing temperature on the microstructure has been studied and reported in the presented research. The annealing temperature was controlled from 900-1300 o C. Kinetic calculations confirmed by the experimental data from the thermal analyses were used to assess the nature of the resultant compound. Interpretation of FT-IR and XRD spectra combined with SEM-EDX observations have identified that a pure single phase was successfully obtained at 1100 o C.

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Preparation, characterization, and methane total oxidation of AAl12O19 and AMAl11O19 hexaaluminate catalysts prepared with urea combustion method

Cited by 37 publications

References 50 publications

Structure–Activity Relationships of Nickel–Hexaaluminates in Reforming Reactions Part I: Controlling Nickel Nanoparticle Growth and Phase Formation

Structure–Activity Relationships of Nickel–Hexaaluminates in Reforming Reactions Part I: Controlling Nickel Nanoparticle Growth and Phase Formation

Catalytic combustion of methane over mixed oxides derived from Co–Mg/Al ternary hydrotalcites

A Novel Technique for Synthesis A Thermal Barrier Coating Material of Lanthanum -Magnesium Hexaaluminate (LaMgAlllO19)

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