POROUS STRUCTURE OF SELF-SUPPORTING PRESSED SILICA DISCS .I. INFRARED SPECTROSCOPIC STUDIES

Infrared Spectroscopic studies of a range of silicas prepared from an Aerosil show that the 3650-cm-1 absorption band present in the spectrum of silica gels corresponds to the regions of interparticle contact within the gel matrix. A comparison of the spectra of powder silicas and the corresponding self-supporting pressed discs suggests that the latter possesses a microporous gel structure. The reactions of the silicas with heavy water and boron trichloride vapor show that it is not possible to differentiate at all accurately between bulk or internal hydroxyls and surface hydroxyls in silica gel structures by hydrogen/deuterium isotopic exchange methods using heavy-water vapor as the exchanging agent. © 1969.