Novel SAPO (silicoaluminophosphate) molecular sieves and synthesis method thereof

The invention provides CHA (chabazite) and GME (gmelinite) symbiotic crystal-phase SAPO (silicoaluminophosphate) molecular sieves and a synthesis method thereof. The SAPO molecular sieves are characterized in that the XRD diffraction pattern of the molecular sieves has a broad peak and spike coexisting characteristic, an inorganic framework has the following chemical composition: (SixAlyPz)O2, wherein x, y and z represent molar fractions of Si, Al and P, x ranges from 0.01 to 0.28, y ranges from 0.35 to 0.55, z ranges from 0.28 to 0.50, and the sum of x, y and z is 1. The synthesized molecular sieves can be used as a catalyst for acid catalysis reactions such as a methanol to olefin reaction and a NOx selective and reductive removal reaction. The invention further relates to an application of the novel SAPO molecular sieves in adsorption and separation of N2, CH4 and CO2.