体系pH值对微波辅助水热合成ZSM-5分子筛结构性质的影响

Effect of pH on Structural Properties of ZSM-5 Molecular Sieve Fabricated via Microwave-assisted Hydrothermal Method

采用微波辅助水热合成法制备了ZSM-5分子筛,借助XRD、SEM、BET、NH3-TPD等表征手段,考察了体系pH值对ZSM-5分子筛结构性质的影响。结果表明,体系pH值对ZSM-5分子筛的微观形貌、比表面积、孔径分布和表面酸强度有较大影响。pH值为11时,制得的ZSM-5分子筛样品的纯度较高,微观形貌为六棱柱状,晶粒分散较好,晶粒尺寸较小且均匀(200nm左右),具有较大的比表面积(313m2·g-1)和较小的平均孔径(2.39nm),表面化学性质以弱酸为主。

ZSM-5 molecular sieves were prepared by microwave-assisted hydrothermal synthesis method. The effects of system pH on the structural properties of ZSM-5 zeolite were investigated by characterization means such as XRD, SEM, BET and NH3-TPD. The results showed: the pH had a great influence on the morphology, specific surface area, pore size distribution and the surface acid strength of the synthesized ZSM-5 zeolite. When the pH value was 11, the prepared ZSM-5 zeolite had higher purity, the microscopic shape was a hexagonal prism and performed better dispersibility, it had more smaller and uniform grain size (about 200 nm), larger specific surface(313 m2/g)and minimum average pore size (2.39 nm), and the surface chemistry was dominated by weak acids.