PURPOSE: To obtain a metal-containing silicate having a specific SiO2/MOx ratio by repeating the lowering and raising of the temperature of a hydrothermal synthesis reaction in a crystallization process by a hydrothermal reaction.
CONSTITUTION: Metal-containing silicate raw materials are mixed with each other with stirring to form a hydrated gel. The hydrated gel is crystallized by a hydrothermal reaction to synthesize a metal-containing silicate. In the crystallization process, the raising and lowering of the hydrothermal synthetic temperature are performed by the control of an electric heater, etc., in the crystallization. The product is cooled, washed with pure water, and subsequently calcined into a metal-containing silicate such as alumino silicate. In the raising and lowering of the hydrothermal reaction, the difference between the temperatures at both the high and lower temperatures is preferably 10-50°C, and the holding times at the high and low temperature times is preferably ≥1hr. The temperature on the high temperature side and the temperature on the low temperature side are 200-220°C and 170-190°C, respectively.
KAMIOKA TOSHITSUGU
SHIGETSU MASAHIKO
YAMADA KEIJI
