Influence of Crystallization and Ageing Time on the Reproducibility of Mesoporous Molecular Sieve SBA-15

ABSTRACT The study aimed to assess how the crystallization and ageing times in SBA-15 synthesis influence the reproducibility and particle size of mesoporous molecular sieves. X-ray diffraction showed that higher crystallization times provide greater reproducibility of mesoporous silica, due to the fact that there is no significant variation in the width and intensity of peaks, while the same is not true for shorter crystallization times. Ageing time does not seem to exercise a significant influence when higher crystallization times are used in the synthesis. Scanning electron microscopy observations revealed that shorter crystallization times led to larger crystals in addition to the formation of large agglomerates, whereas with higher crystallization times the trend is to obtain smaller and more uniform grains. It is proposed that hydrogen bonds may be responsible for the formation of smaller particles and it is also established that depending on the synthesis conditions the reproducibility of the process can become low.摘要 本研究旨在探究SBA-15合成过程中的晶化时间与陈化时间对介孔分子筛（mesoporous molecular sieves）的合成重现性及粒径的影响规律。X射线衍射（X-ray Diffraction）结果显示，较长的晶化时间可提升介孔二氧化硅（mesoporous silica）的合成重现性，这是由于此时衍射峰的半高宽与强度无显著变化；而较短晶化时间则无法实现这一点。当合成采用较长晶化时间时，陈化时间似乎对合成结果无显著影响。扫描电子显微镜（Scanning Electron Microscopy）观测表明，较短的晶化时间不仅会生成更大的晶粒，还会形成大量团聚体；而较长晶化时间则更易获得尺寸更小且分布更为均匀的晶粒。本研究提出，氢键（hydrogen bonds）可能是形成较小粒径颗粒的原因，同时证实：依据合成条件的不同，该合成过程的重现性可能会降低。