Preparation and characterization of mesoporous molecular sieves containingAl, Fe or Zn

Silica M41S type materials have been prepared starting from the mixture: 0. 29 Na2O:0.12 CTABr:1 SiO2:100 H2O using water-glass as silica source. Synth eses were carried out at three different temperatures: 303. 343 and 413 K. The effect of the synthesis temperature on the nature of the products, the presence of Al, Fe or Zn, as well as the properties of the so-obtained mate rials and their thermal stability were studied. XRD, N-2 adsorption, FTIR a nd NMR techniques were used for the characterization of the products. The a dopted procedure enables the synthesis of thermally stable hexagonal mesopo rous materials from hydrogels with Si/Al ratios greater than or equal to 10 . The Al forms contain both Bronsted and Lewis acid sites, whereas the Fe f orms only contain Lewis acidic sites. (C) 2001 Elsevier Science B.V. All ri ghts reserved.