Physicochemical and Technological Aspects of the Hydrothermal Modification of Complex Sorbents and Catalysts. Part I. Modification of Porous and Crystalline Structures

This paper deals with the hydrothermal modification of the physicochemical properties of complex mineral sorbents and catalysts. The hydrothermal modification of alumina, magnesia, ferric oxide and zirconia/silica hydro- and xero-gels as well as other complex adsorbents obtained by the coprecipitation and mechanical stirring of suitable components is discussed. The paper deals with the following topics: (a) the physicochemical bases of the hydrothermal method; (b) methodological and technological problems of the hydrothermal treatment of adsorbents; (c) hydrothermal modification of porous structure parameters (specific surface area, pore volume and size); and (d) characteristics of the hydrothermal modification of the porous structure of multicomponent adsorbents and catalysts. In addition, the mechanism of the hydrothermal modification of the porous structure of composite materials is discussed

Physicochemical and Technological Aspects of the Hydrothermal Modification of Complex Sorbents and Catalysts. Part II. Modification of Phase Composition and Mechanical Properties

Two main ways of applying the method of solid hydrothermal treatment have been considered: (a) hydrothermal modification of polycrystalline adsorbents and catalysts; and (b) hydrothermal synthesis of materials possessing regular porosity (zeolite-like, laminar and others). Modification processes of phase composition and mechanical properties of complex adsorbents and catalysts were discussed. The essential features of hydrothermal crystallization in multicomponent systems have been presented

Studies of the Effects of Aerosilogel Modification by Organic Acids under High Pressures

Preliminary studies of silica surface modification by means of some organic acids under high reagent pressures were carried out. The reaction took place in a steel autoclave. Suitably granulated aerosilogel and acetic, mono- and trichloro-acetic as well as sulphosalicylic acids were used. Physical and chemical adsorption processes were checked by infrared spectroscopy, thermogravimetry and Potentiometric titration. The specific surface area and total volume of pores of the prepared samples were determined. The studies showed some possibilities of attaching organic radicals containing an acid group to the silica surface. This process can be accomplished in one stage