Textured macro- and mesoporous alumina samples designed in the presence of different surfactant types

Petrolini, Davi D.; Pulcinelli, Sandra Helena; Santilli, Celso Valentim; Martins, Leandro

doi:10.1007/s10971-014-3323-7

Cited by 6 publications

(3 citation statements)

References 14 publications

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“…With the aid of P123 and additional tetrabutyl ammonium hydroxide, López Pérez et al were able to obtain pure α-Al 2 O 3 with A BET in the range of 16-24 m 2 /g by evaporation induced self-assembly [79], while Zhang et al report a value of 18 m 2 /g with additional PEG8000 after calcination at 1200 • C [80,81]. Other approaches include EDTA, leading to α-Al 2 O 3 powder with up to 14 m 2 /g [82], a combination of chelating agents with acrylamide [83], or other surfactants, for instance [84,85]. We recently reported on the use of citric acid as a phase separating agent [68], which has been known to act as a template in alumina sol-gel syntheses [86][87][88][89][90] but never brought to comparable porosity values in α-Al 2 O 3 before.…”

Section: Introducing Porosity Via Soft Templating In Sol-gel Synthesesmentioning

confidence: 99%

Towards Macroporous α-Al2O3—Routes, Possibilities and Limitations

2020

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This article combines a systematic literature review on the fabrication of macroporous α-Al2O3 with increased specific surface area with recent results from our group. Publications claiming the fabrication of α-Al2O3 with high specific surface areas (HSSA) are comprehensively assessed and critically reviewed. An account of all major routes towards HSSA α-Al2O3 is given, including hydrothermal methods, pore protection approaches, dopants, anodically oxidized alumina membranes, and sol-gel syntheses. Furthermore, limitations of these routes are disclosed, as thermodynamic calculations suggest that γ-Al2O3 may be the more stable alumina modification for ABET > 175 m2/g. In fact, the highest specific surface area unobjectionably reported to date for α-Al2O3 amounts to 16–24 m2/g and was attained via a sol-gel process. In a second part, we report on some of our own results, including a novel sol-gel synthesis, designated as mutual cross-hydrolysis. Besides, the Mn-assisted α-transition appears to be a promising approach for some alumina materials, whereas pore protection by carbon filling kinetically inhibits the formation of α-Al2O3 seeds. These experimental results are substantiated by attempts to theoretically calculate and predict the specific surface areas of both porous materials and nanopowders.

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Section: Introducing Porosity Via Soft Templating In Sol-gel Synthesesmentioning

confidence: 99%

Towards Macroporous α-Al2O3—Routes, Possibilities and Limitations

2020

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“…Mixed oxides of magnesium and aluminum having macro-mesoporous structures and presenting tuneable amount of macropores and high BET area were already obtained. [16][17][18] In the emulsion method, the entrapment of dispersed oil droplets by a continuous phase occurs during the sol-gel transition of the system, induced by a rise in pH or by a change in temperature. 13 The addition of a surfactant is necessary to intermediate the kinetic stability of the emulsion and to avoid the assemblage of the isolated droplets by placing itself inbetween the oil-water interfaces.…”

Section: Introductionmentioning

confidence: 99%

Catalytic performance of texturally improved Al–Mg mixed oxides derived from emulsion-synthesized hydrotalcites

et al. 2018

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“…Aer heat treatment, these mixed oxides have various unique properties as providing an ideal balance of acid and base sites [13][14][15][16][17] and unique textural properties, which have impact on metals dispersion and therefore on ethanol conversion to acetaldehyde and ethyl acetate. 3,5 In a previous study, [18][19][20] an emulsion-mediated method was used to produce Al-Mg mixed oxides from hierarchically ordered hydrotalcite precursors that gave a high specic surface area. It is expected that the textural properties of these materials may reduce metal agglomeration and increase the interparticle space, and then to have an incremental effect on the catalyst performance.…”

Section: Introductionmentioning

confidence: 99%