Temperature removal of templating agent from MCM-41 silica materials

Temperature programmed desorption coupled with mass spectrometry, FT-IR spectroscopy with photoacoustic (PA) detector have been applied to investigate organic template degradation during thermal treatment of as synthesized MCM-41 silica. Micelle templated silica was prepared using C18 trimethylammonium bromide. The processes accompanying the template transformations were investigated in argon flow and mixed oxygen-helium atmosphere. Template removal appears to be completely different in the inert gas atmosphere and at the presence of oxygen. The results obtained for as synthesized sample were compared with those for calcined sample in air and additionally thermally treated in oxygen flow. Spectroscopic data indicate the presence of a variety of chemical species on silica surface after template removal. Additional oxidation of calcined sample leads to elimination of most organic functional groups and increase of siloxane bridges as a product of surface silanols condensation. (C) 2005 Elsevier B.V. All rights reserved.