Kinetic Monte Carlo modeling of silicate oligomerization and early gelation†

Abstract

We present a lattice-gas kinetic Monte Carlo model to investigate the formation of silicate oligomers, their aggregation and the subsequent gelation process. In the early oligomerization stage, the 3-rings are metastable, 5-rings and 6-rings are formed in very small quantities, 4-rings are abundant species, linear and branched species are transformed into more compact structures. Results reveal that the gelation proceeds from 4-ring containing species. A significant amount of 5-rings and 6-rings, sharing Si with 4-ring, form in the aging stage. These reveal the formation mechanism of silicate rings and clusters during zeolite synthesis.