The preparation of controlled pore alumina

Vogel, Roger F.; Marcelin, G.; Kehl, W.L.

doi:10.1016/s0166-9834(00)80294-8

Cited by 46 publications

(22 citation statements)

References 5 publications

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“…The final mass loss measured on A samples was 60%. The small difference with the theoretical mass loss (63%) can be attributed to the presence of amorphous Al-containing phase(s) [9,28]. Once again, it is important to note that since AACH mass loss during calcination is higher than boehmite ones, less AACH-derived alumina will be obtained for a same solid concentration in the final suspension.…”

Section: Precursor -Alumina Transitionmentioning

confidence: 81%

“…Ammonium aluminium carbonate hydroxide (AACH, with formula NH 4 Al(OH) 2 CO 3 ), also called NH 4dawsonite, can be an interesting alternative choice for preparation of γ-Al 2 O 3 with high purity level and new textural properties. Various methods can be used to synthesize AACH [8], but the main one remains the precipitation of aluminium salts (Al(NO 3 ) 3 , (NH 4 )Al(SO 4 ) 2 , or AlCl 3 ) in aqueous phase with precipitating agents such as (NH 4 ) 2 CO 3 or NH 4 HCO 3 [9,10]. Influence of several parameters on the product properties have been studied so far: reactants [11], contacting mode [12][13][14][15], pH [16,17], molar ratio [9,15,18], alternative medias [17,19].…”

Section: Introductionmentioning

confidence: 99%

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Ammonium aluminium carbonate hydroxide NH4Al(OH)2CO3 as an alternative route for alumina preparation: Comparison with the classical boehmite precursor

et al. 2017

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Section: Precursor -Alumina Transitionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Ammonium aluminium carbonate hydroxide NH4Al(OH)2CO3 as an alternative route for alumina preparation: Comparison with the classical boehmite precursor

et al. 2017

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“…1200 o C 까지 가열하면 밀도가 크고 결정성이 좋은 알파 알루미 나(α-Al 2 O 3 )가 생성되는데 가열과정에서 생기는 여러 타 입의 알루미나 Al 2 O 3 •χH 2 O(0 < χ < 1)를 전이 알루미나라 고 한다. 8,9) 일반적으로 전이 알루미나 중의 하나인 감마 알루미나를 얻기 위해서는 보헤마이트를 낮은 온도로 소 성하거나, pseudo-boehmite를 300~400 o C로 가열하여 제 조하기도 한다. Fig.…”

Section: 7)unclassified

Fabrication of Activated Alumina Using Aluminum Hydroxide by a Hydrothermal Process

Bae¹,

Lee²

2013

Journal of the Korean Ceramic Society

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Activated alumina was fabricated with aluminum hydroxide in this study. High-purity alumina gel and boehmite were prepared from aluminum hydroxide by a hydrothermal process and fired to activate alumina having a surface area of 380~480 m 2 /g with less loss of ignition. The aging and drying condition during the fabrication process affected the loss of ignition, the sedimentation time of the alumina suspension, as well as the surface area of the activated alumina. For pellet-type activated alumina, the pre-fired alumina gel and boehmite were press-formed and fired at 400 o C and 550 o C for 6 h, respectively. The fired pellets showed a low density of 2.02 .2 g/cm 3 with 20% firing shrinkage and sufficient handling strength. In this study, a new fabrication process for high-quality activated alumina with aluminum hydroxide is introduced. The effects of the processing parameters on the activated alumina properties are also examined.

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“…Influence of several parameters on the product properties have been studied so far: reactants (Shin et al, 2014), contacting mode (Dubert et al, 2011;Hu et al, 2012;Ma et al, 2001;Santiago et al, 2006), pH (C. H. Liu et al, 2012), molar ratio (Hu et al, 2012;Vogel et al, 1984), alternative medias (Duan et al, 2013;... However, influence of the micromixing time on the NH 4dawsonite textural properties has, to our knowledge, never been investigated.…”

Section: Introductionmentioning

confidence: 99%

Influence of micromixing time and shear rate in fast contacting mixers on the precipitation of boehmite and NH4-dawsonite

Lafficher

Digne

Salvatori

et al. 2018

Chemical Engineering Science

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The textural properties of γ-alumina catalyst supports largely depend on the solid properties of their precursors. Precipitation in fast contacting mixers of two precursors, boehmite and NH 4-dawsonite, were investigated in order to obtain different and enhanced solid features. The mixing devices, a sliding surface mixing device (SSMD) and a rotorstator mixer (RSM), were operated continuously. Micromixing was characterized by using a competitive parallel reaction system (iodide-iodate). It was possible to achieve micromixing time from 1 to 200 ms according to the type of mixer and the operating conditions. The micromixing times assessed experimentally are in correct agreement with the theoretical ones. For boehmite precursor, the micromixing time had not a decisive influence on the crystallite size. Better control of the particle surface area was obtained considering the shear rate level, maybe due to a disordered aggregation. Conversely, reduction of the crystallite size with a decrease of the micromixing time was observed with NH 4-dawsonite. A possible explanation lies in a higher local supersaturation, leading to a more intense primary nucleation. Moreover, it was possible to adjust the pore volume of the NH 4-dawsonite's aggregates with the operating conditions to quite a large extent (0.2 up to 0.8 cm 3 .g-1).

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The preparation of controlled pore alumina

Cited by 46 publications

References 5 publications

Ammonium aluminium carbonate hydroxide NH4Al(OH)2CO3 as an alternative route for alumina preparation: Comparison with the classical boehmite precursor

Ammonium aluminium carbonate hydroxide NH4Al(OH)2CO3 as an alternative route for alumina preparation: Comparison with the classical boehmite precursor

Fabrication of Activated Alumina Using Aluminum Hydroxide by a Hydrothermal Process

Influence of micromixing time and shear rate in fast contacting mixers on the precipitation of boehmite and NH4-dawsonite

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