Method for synthesizing SAPO-20 molecular sieve

The invention discloses a method for synthesizing an SAPO-20 molecular sieve. The method comprises steps as follows: firstly, an SAPO-34 molecular sieve or a waste SAPO-34 molecular sieve catalyst isdissolved in a sodium hydroxide solution, the mixture is put in a high-pressure reactor and crystalized at the temperature of 160 DEG C for 1-3 days, cooling, washing and drying are performed after crystallization, and the SAPO-20 molecular sieve is obtained. The new route for synthesizing the SAPO-20 molecular sieve is developed, and a utilization way of the waste SAPO-34 molecular sieve catalystis provided and can serve as an energy-saving, consumption-reducing and comprehensive-utilization new exploration mode in an SAPO-34 molecular sieve catalyst process. Particularly, when the method isused for synthesizing the SAPO-20 molecular sieve, a roasting template agent is not required after complete crystallization, a synthesized product has regular morphology and uniform particle size, can be used for separation ad