Abstract: MCM-48 was synthesized with tetraethylorthosilicate (TEOS) as silica source and cetyltrimethylammonium bromide (CTAB) as template at high pressure (c a.7 MPa) and 373 K. The synthesized compounds were characterized using different analytical techniques such as X-ray diffraction,N2 adsorption and desorption m easurement,and 29Si MAS NMR.MCM-48 synthesized at high pressure appeared higher thermal and hydrothermal stability than that synthesized at autogenous pressure .The 29Si MAS NMR results demonstrated that high pressure promoted the wall poly merization and leaded to a high quality MCM-48.MCM-48 was also synthesized wit h such a low ratio of CTAB/Si as 0.16,but that synthesized with high ratio of CT AB/Si was more stable.

Key words: MCM-48, Mesopore, Template, High pressure, Hydrothermal stability