hydrothermal synthesis method uses water glass, sodium metaaluminate and sodium hydroxide as raw materials. For the preparation of dilute solution of water glass and the preparation of sodium metaaluminate, please refer to 3A molecular sieve.
Mix water glass and sodium metaaluminate according to a certain molar ratio (generally Na2O:Al2O3:SiO3:H2O = 3.1:l:8:192), add sulfuric acid (diluted to 2.25mol/L), stir at 20~30 ℃ for a period of time, add orienting agent, stir for another half hour, raise the temperature to 50 ℃, age for a certain period of time, and quickly raise the temperature to (102±2)℃, crystallization for 16-24h (control of the alkalinity of the mother liquor), the resulting crystallization is filtered, washed with water at 50-60 ℃, calcium chloride is added for ion exchange (exchange degree 70%), then filtered and washed with water until there is no chloride ion, dried at 120 ℃, kneaded with silica sol, formed, burned and activated to obtain Ca-Y molecular sieve.