Crystal chemistry of hexaaluminates: β-alumina and magnetoplumbite structures

Iyi, Nobuo; Takekawa, Shunji; Kimura, Shigeyuki

doi:10.1016/0022-4596(89)90048-0

Cited by 141 publications

(103 citation statements)

References 54 publications

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“…Iyi et al 20 reported that only the mono-, di-and trivalent ions with radius above 1.10 Å could be accommodated in the mirror plane of hexaaluminate crystal. Since the radius of the Ce(III) ion is 1.18 Å , it seems that it could be accommodated in the hexaaluminate lattice.…”

Section: Effect Of Ce Introduction On the Catalystsmentioning

confidence: 99%

Synthesis of the high-surface-area Ce_xBa_1−xMnAl₁₁O_ycatalyst in reverse microemulsions using inexpensive inorganic salts as precursors

Teng

Tian

et al. 2005

Green Chem.

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The high-surface-area Ce x Ba 12x MnAl 11 O y (x 5 0, 0.1, 0.2, 0.3) catalysts were synthesized in the nonionic reverse microemulsion (ME), using the inorganic salts as the reactants. The supercritical drying (SCD) and conventional oven drying (CD) methods were used to remove the water in hydrogels, respectively. The Ce x Ba 12x MnAl 11 O y samples were characterized by N 2 -adsorption, transmission electron microscopy (TEM), TGA-DTA, and X-ray powder diffraction (XRD). The effects of the microemulsion composition, the drying method, the calcination temperature and the introduction of Ce on the catalysts were investigated. The results showed that the morphology of the catalyst was controlled by the microemulsion microstructure; and the homogeneity of the precursor was improved effectively by the reverse microemulsion method and the supercritical drying method. Due to the high homogeneity of the precursors, the initial formation temperature of the hexaaluminate phase decreased to lower than 1100 uC. The BaMnAl 11 O 19 catalyst had high surface area (72.4 m 2 g 21) and high catalytic activity (T 10 5 445 uC) for methane combustion. When Ce was introduced, the Ce x Ba 12x MnAl 11 O y catalyst (x 5 1) had the higher activity (T 10 5 430 uC) than that of the BaMnAl 11 O 19 one due to a synergetic effect between Ce and Mn.

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Section: Effect Of Ce Introduction On the Catalystsmentioning

confidence: 99%

Synthesis of the high-surface-area Ce_xBa_1−xMnAl₁₁O_ycatalyst in reverse microemulsions using inexpensive inorganic salts as precursors

Teng

Tian

et al. 2005

Green Chem.

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“…Owing to huge improvements in their preparation, perovskites (LnBO 3 , in which Ln is a lanthanide (usually La) and the B cation possesses two valence states like Mn, Co, or Fe, e.g., La 1−x M x MnO 3+δ with M = Ce, Sr), spinels, hexaaluminates and some other oxide structures can replace noble metals in a number of processes. Hexaaluminates (AB x Al 12−x O 19−δ , where A x+ and B y+ are a lanthanide and a transition/noble metal cation, respectively, are formed of alternate layers of alumina spinel blocks and mirror planes in which a large A cation is located [69]). …”

Section: Total Oxidation Reactionsmentioning

confidence: 99%

Heterogeneous Catalysis on Metal Oxides

2017

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This review article contains a reminder of the fundamentals of heterogeneous catalysis and a description of the main domains of heterogeneous catalysis and main families of metal oxide catalysts, which cover acid-base reactions, selective partial oxidation reactions, total oxidation reactions, depollution, biomass conversion, green chemistry and photocatalysis. Metal oxide catalysts are essential components in most refining and petrochemical processes. These catalysts are also critical to improving environmental quality. This paper attempts to review the major current industrial applications of supported and unsupported metal oxide catalysts. Viewpoints for understanding the catalysts' action are given, while applications and several case studies from academia and industry are given. Emphases are on catalyst description from synthesis to reaction conditions, on main industrial applications in the different domains and on views for the future, mainly regulated by environmental issues. Following a review of the major types of metal oxide catalysts and the processes that use these catalysts, this paper considers current and prospective major applications, where recent advances in the science of metal oxide catalysts have major economic and environmental impacts.

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“…There are two typical hexaaluminate structures depending on the composition and the defectivity of the mirror plane, namely, ␤-Al 2 O 3 and magnetoplumbite (MP) corresponding to the same space group P6 3 /mmc (No. 194) [14,15]. In the spinel block of both ␤-Al 2 O 3 and MP structures, the crystallographic sites of Al atoms are the same.…”

Section: Introductionmentioning

confidence: 81%

“…However, our previous work [21,22] suggested that the activity of N 2 O decomposition was greatly increased by incorporating Ir into BaFeAl 11 O 19 compared with Ir outside the framework. In hexaaluminate structure, there are various Al coordination sites available for the occupation of noble metal ions [14]. Nevertheless, there is still not a clear picture on which crystallographic sites are preferentially occupied by noble metal ions and thus the effect on the catalytic activity.…”

Section: Introductionmentioning

confidence: 98%

Effect of Ir crystallographic site on the catalytic performance of Ir-substituted barium hexaferrites for N2O decomposition

Zhu

Wang

Zhang

et al. 2011

Applied Catalysis A: General

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Crystal chemistry of hexaaluminates: β-alumina and magnetoplumbite structures

Cited by 141 publications

References 54 publications

Synthesis of the high-surface-area Ce_xBa_1−xMnAl₁₁O_ycatalyst in reverse microemulsions using inexpensive inorganic salts as precursors

Synthesis of the high-surface-area Ce_xBa_1−xMnAl₁₁O_ycatalyst in reverse microemulsions using inexpensive inorganic salts as precursors

Heterogeneous Catalysis on Metal Oxides

Effect of Ir crystallographic site on the catalytic performance of Ir-substituted barium hexaferrites for N2O decomposition

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Crystal chemistry of hexaaluminates: β-alumina and magnetoplumbite structures

Cited by 141 publications

References 54 publications

Synthesis of the high-surface-area CexBa1−xMnAl11Oycatalyst in reverse microemulsions using inexpensive inorganic salts as precursors

Synthesis of the high-surface-area CexBa1−xMnAl11Oycatalyst in reverse microemulsions using inexpensive inorganic salts as precursors

Heterogeneous Catalysis on Metal Oxides

Effect of Ir crystallographic site on the catalytic performance of Ir-substituted barium hexaferrites for N2O decomposition

Contact Info

Product

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Synthesis of the high-surface-area Ce_xBa_1−xMnAl₁₁O_ycatalyst in reverse microemulsions using inexpensive inorganic salts as precursors

Synthesis of the high-surface-area Ce_xBa_1−xMnAl₁₁O_ycatalyst in reverse microemulsions using inexpensive inorganic salts as precursors