Formation process of MCM-41 precursor and porous texture of MCM-41
The formation process of the MCM-41 precursors (silicate/surfactant complex) was investigated on the basis of the pH titration curves of Na{sub 4}SiO{sub 4} in the presence of [C{sub 16}H{sub 33}N(CH{sub 3}){sub 3}]Cl. Measurements of the pH titration curves were carried out using the computer-controlled gravimetric titrator constructed in their laboratory. The white precipitate (MCM-41 precursor) was abruptly formed at pH 11.1 (298 K) and at pH 9.9 (343 K). Formation of the MCM-41 precursor can be explained by coagulation of the rod-like micelle colloids whose surface is covered by the condensed silicate anions of (HSiO{sub 3}){sub n}{sup n{minus}}. The porous texture of the MCM-41 samples whose precursors were synthesized under different conditions was analyzed on the basis of the adsorption isotherms of nitrogen at 77 K. It has been shown that the MCM-41 sample whose precursor was prepared at pH 9.9 and 343 K shows one sharp peak (r{sub p} = 1.65 nm) in the pore size distribution curve, but the MCM-41 samples whose precursors were prepared at pH 6.5--5.0 and 343 K give two peaks (r{sub p} = 1.66 nm and r{sub p} = 2.12--2.36 nm). The appearance of the second peak (r{sub p} = 2.12--2.36 nm) has been considered to be in connection with the destruction of the MCM-41 precursor into small fragments in acidic medium.
- Research Organization:
- Kwansei Gakuin Univ., Nishinomiya (JP)
- OSTI ID:
- 20075570
- Journal Information:
- Journal of Colloid and Interface Science, Vol. 224, Issue 2; Other Information: PBD: 15 Apr 2000; ISSN 0021-9797
- Country of Publication:
- United States
- Language:
- English
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