Preparation and sintering pure nanocrystalline α-alumina powder

Karagedov, G. R.; Myz, A. L.

doi:10.1016/j.jeurceramsoc.2011.08.012

Cited by 34 publications

(18 citation statements)

References 19 publications

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“…Di erences in crystalline structure may result in changes in physical and chemical properties of aluminas as the support [3,4]. The alumina phases have two broad categories of oxygen anions arrangements, a Face-Centered Cubic (FCC) or a Hexagonal ClosePacked (HCP).…”

Section: Introductionmentioning

confidence: 99%

Influence of calcination parameters on the properties of alumina as a catalyst support

Komeili

Ravanchi²,

Taeb

2016

Scientia Iranica

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Abstract. The preparation history of Al 2 O 3 strongly determines its properties for the application as a catalyst support. The interaction of calcination heating rate and temperature and its in uence on the structural, textural, and acidic properties of alumina were studied. Commercial -alumina was calcined at 800 C, 900 C, 1000 C, 1050 C, 1100 C, and 1150 C by 2.5 C/min, 5 C/min, and 10 C/min. By increasing temperature up to 1050 C, transition aluminas ( , , and ) were reported, but the heating rate accelerated phase transformation and changed the amount of each phase in the samples. At 1100 C and 1150 C, -alumina appeared. Mesopore alumina with di erent surface areas (265-126 m 2 /g) was synthesized at calcination temperature from 800 C to 1050 C; when temperature reached 1100 C, the surface area decreased drastically and was around 14 m 2 /g. Interaction of heating rate on the temperature had minimal e ect on the surface area of samples, but considerable e ect on the acidic properties. The intensity of acidic properties was a ected by heating rate with nonlinear pro les. By increasing the heating rate, the ratio of Al cations occupied tetrahedral per octahedral sites and defect of crystal structures increased, so the surface acidity of aluminas was increased.

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Section: Introductionmentioning

confidence: 99%

Influence of calcination parameters on the properties of alumina as a catalyst support

Komeili

Ravanchi²,

Taeb

2016

Scientia Iranica

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“…␣-Alumina has been conventionally produced by annealing aluminum hydroxide derived from aluminum salts or minerals at temperatures higher than 1000 • C [6][7][8]. This method requires high temperatures and thus a high amount of energy.…”

Section: Introductionmentioning

confidence: 99%

Seeding technique for lowering temperature during synthesis of α-alumina

Kobayashi

Mabuchi

Hama

et al. 2015

Journal of Asian Ceramic Societies

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a b s t r a c tThis paper reports a method for producing ␣-Al 2 O 3 at low temperature using a seeding technique. A white product obtained by hydrolyzing aluminum isopropoxide in water at 80 • C was peptized using acetic acid at 80 • C, which transformed the white product to a transparent alumina sol. ␣-Al 2 O 3 particles were added to the alumina sol as seed material; the sol containing ␣-Al 2 O 3 particles was then transformed to an ␣-Al 2 O 3 -seeded alumina gel by drying the sol at room temperature. The non-seeded alumina gel remained boehmite after annealing at 300 • C and crystallized into ␥-Al 2 O 3 and ␣-Al 2 O 3 at temperatures between 300 and 500 • C and between 900 and 1100 • C, respectively. The ␣-Al 2 O 3 seeding promoted crystallization of the alumina gel into ␣-Al 2 O 3 . The promotion of crystallization was significant with an increase in ␣-Al 2 O 3 particle content by weight in the final seeded alumina gel. With an ␣-Al 2 O 3 particle content of 5%, the seeded alumina gel was partially crystallized into ␣-Al 2 O 3 by annealing at a temperature as low as 900 • C.

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“…If the syntheses of aluminium oxide are the sol-gel method using carboxylic acids [28,29] or ammonia [30,31], the resulting precursor is usually converted into corundum annealing at 800-1300 1C. In the reactions of aluminium nitrate with glycine, as a rule, there is a formation of an amorphous product, which upon annealing up to 600-800 1C transforms into g-Al 2 O 3 [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Solution combustion synthesis of α-Al2O3 using urea

Журавлев

Бамбуров

Бекетов

et al. 2013

Ceramics International

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The processes involved in the solution combustion synthesis of a-Al 2 O 3 using urea as an organic fuel were investigated. The data describing the influence of the relative urea content on the characteristic features of the combustion process, the crystalline structure and the morphology of the aluminium oxide are presented herein. Our data demonstrate that the combustion of stable aluminium nitrate and urea complexes leads to the formation of a-alumina at temperatures of approximately 600-800 1C. Our results, obtained using differential thermal analysis and IR spectroscopy methods, reveal that the low-temperature formation of a-alumina is associated with the thermal decomposition of an a-AlO(OH) intermediate, which was crystallised in the crystal structure of the diaspore.

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Preparation and sintering pure nanocrystalline α-alumina powder

Cited by 34 publications

References 19 publications

Influence of calcination parameters on the properties of alumina as a catalyst support

Influence of calcination parameters on the properties of alumina as a catalyst support

Seeding technique for lowering temperature during synthesis of α-alumina

Solution combustion synthesis of α-Al2O3 using urea

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