ИСТИНА

The aim of this work is to clarify the role of reactions conditions to the structure and amount of Si-sites formed during the hydrothermal synthesis of SAPO-11. The synthesis of SAPO-11 from a mixture Al2O3: P2O5: (0.3-0.5)SiO2: (1.0-1.5)DPA: 47H2O: 6i PrOH studied at 473K and different reaction time. All the samples after washing and drying were characterized by XRD, SEM, 29Si, 31P and 27Al MAS NMR methods. Two pathways of Si incorporation into the SAPO 11 structure were observed. The first pathway leads to the formation of silica domains in SAPO 11 and preferably is carried out at early stage of synthesis, when the rate of SAPO-11 formation is high. The incorporation of Si in the isolated position was observed only during the final step of synthesis, when the bulk of SAPO-11 was already formed.