Pore ordering in mesoporous matrices induced by different directing agents

Putz, A-M. and Cecilia, S. and Ianăşi, Catalin and Dudás, Zoltán Imre and Székely, Noémi Kinga and Almásy, László (2015) Pore ordering in mesoporous matrices induced by different directing agents. JOURNAL OF POROUS MATERIALS, 22. pp. 321-331. ISSN 1380-2224

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Abstract

Mesoporous silica particles of MCM - 41 type were synthesized by sol - gel method fr om tetraethyl orthosilicate (TEOS) in 2 - methoxyethanol and deionized water mixture in base conditions at room temperature. Ammonia or sodium hydroxides were used as catalysts and cetyl - trimethylammonium bromide (CTAB) and n - dodecyl - trimethylammonium bromid e (DTAB) as structure directing agents. The porosities and the ordered structure have been analyzed using transmission and scanning electron microscopy, small angle neutron and X - ray diffraction, nitrogen adsorption, thermal analysis and FTIR spectroscopy. The samples consist of spherical particles of sub - micrometer size, with radially arranged pores. The comparison of the effect of the different surfactants and catalysts shows that by varying the surfactant type and their proportion, the pore sizes can be controlled. As compared to the commonly used ammonia catalyst, the use of NaOH as catalyst results in a much smaller porosity of the as - prepared materials. These materials are not resisting to the heat treatment at 700 ºC used for the template removal, and the ordered porous structure is completely lost. Keywords: mesoporous silica, MCM - 41, hexadecyl - trimethylammonium bromide, dodecyl - trimethyl ammonium bromide.

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