Study on the crystalizaiton mechanism of SAPO-34 zeolite

The structure and composition of SAPO-34 zeolite synthesized by conventional hydrothermal process and dry gel liquid phase crystallization process were investigated by XRD,SEM,ICP-AES and MAS NMR characterization methods.The results showed that SAPO-34 zeolite with impurity was obtained by conventional hydrothermal process.Impurity was appeared due to fewer active silicon species with high rate of silica source depolymerization and polycondensation.Pure SAPO-34 zeolite was synthesized by dry gel liquid-phase crystallization process.The rate of nucleation and growth was controlled by slower rate of silica source depolymerization.Samples of relative crystallinity increased gradually.