Changes in Hydration Properties of Silica Gel in a Process of Its Carbonization by Pyrolysis of Acetylacetone Zn (Ti) Acetylacetonates.
Changes in hydration properties of different compounds in a process of formation of a complex adsorbent comprising carbon and TiO2 or Zn2SiO4 on its surface were studied by 1H NMR spectroscopy under conditions of a liquid phase freezing. Adsorbents were synthesized on the basis of a mesoporous silica gel, the surface of which was covered with a carbon layer formed in a process of a high temperature pyrolysis of acetylacetone. Titanium oxide and zinc silicate on the surface of a parent silica gel were formed by a pyrolysis of acetylacetonates of the corresponding metals. It has been revealed that the main types of surface-active sites for the adsorbed water molecules on the carbosil surface are the systems of condensed benzene nuclei of a carbon component of the surface and hydroxyl groups of silica surface. Zn2SiO4 and TiO2 have been formed in a process of pyrolysis of the corresponding metal acetylacetonates. Water bound with the oxide component of the carbosil surface exceeds 80% of the total amount of the adsorbed water. The carbon component of the surface is localized mainly in the narrowest pores. A minimum value in the free surface energy was recorded for the carbosil sample. Copyright 1998 Academic Press.
Turov
VV
Institute of Surface Chemistry of NAS of Ukraine, Kiev, 252022, Ukraine
Leboda
R
Skubiszewska-Zi
J