The Synthesis of Oxide Materials by Hydrothermal Decomposition of Chloride Solutions
Доклады на конференциях
The study of the metal chlorides hydrolysis is of particular interest in connection with the problems of materials science, geochemistry, general and technical chemistry and chemical engineering problems. In this work a special attention is paid to study of synthesis of aluminum hydroxide from solutions of aluminum chloride under hydrothermal conditions. It is assumed the simultaneous presence of chlorides' impurities of Fe, K, Na, Ca and Mg in the initial aluminum-chloride solutions. The original technique is developed for the moving of the balance of the following reversible reactions in the direction of reaction products formation, i.e., right:
AlCl3 + 3H2O ↔ Al(OH)3 + 3HCl ↑
FeCl3 + 3H2O ↔ Fe(OH)3 +3HCl ↑
Hydrothermal synthesis of Al2O3, AlO(OH) and Fe2O3 as a result of aluminum-chloride solutions decomposition was realized using a batch type autoclave over the range of temperature from 453 to 483K at a pressure of 1.6 -2.3 MPa for 4-10 hours. Alumina products obtained with the hydrolyzate is evaporated to a volume of 8-10 ml at 253 K, cooled to room temperature and washed with distilled water followed by centrifugation. The dried at 80 ° C for 5 hours alumina products were calcined in a muffle furnace at 573 K for 2 hours. The proposed method of hydrothermal decomposition of Me-chloride solutions solves the problem of the completeness of hydrolysis both aluminum chloride and ferric chloride. It has been shown that the pH of the solution (basic), temperature, pressure, ionic strength, the presence of coagulants, surfactants and other components (impurities) affect on the processes of metal hydroxides deposition and control the formation of oxide materials with desired texture.