Synthesis of MCM-48 under high pressure

MCM-48 was synthesized with tetraethylorthosilicate (TEOS) as silica source and cetyltrimethylammonium bromide (CTAB) as template at high pressure (ca. 7 MPa) and 373 K. The synthesized compounds were characterized using different analytical techniques such as X-ray diffraction, N-2 adsorption and desorption measurement, and Si-29 MAS NMR. MCM-48 synthesized at high pressure appeared higher thermal and hydrothermal stability than that synthesized at autogenous pressure. The Si-29 MAS NMR results demonstrated that high pressure promoted the wall polymerization and leaded to a high quality MCM-48. MCM-48 was also synthesized with such a low ratio of CTAB / Si as 0.16, but that synthesized with high ratio of CTAB / Si was more stable.