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.
Keywords: reproducibility, SBA-15, crystallization time, ageing time.