Adsorption is a low-energy separation process especially advantageous when the
components to be separated are similar in nature or have a low molar concentration.
The choice of the adsorbent is the key factor for a successful separation, and among
them periodic mesoporous silicas (PMS) are of importance because of their pore
sizes, shapes and connectivity. Furthermore, they can be modified by post-synthesis
functionalisation, which provides a tool for tailoring them to specific applications.
SBA-2 and STAC-1 are two types of PMS characterised by a three-dimensional
pore system of spherical cages interconnected by a network of channels whose
formation process was until now obscure. In this work the kinetic Monte Carlo
(kMC) technique has been extended to simulate the synthesis of these complex
materials, presenting evidence that the interconnecting network originates from
spherical micelles touching during their close-packing aggregation in the synthesis.
Moreover, for the first time atomistic models for these materials were obtained with
realistic pore-surface roughness and details of the possible location of its interaction
sites.
Grand Canonical Monte Carlo (GCMC) simulations of nitrogen, methane and
ethane adsorption in the materials pore models show excellent agreement with
experimental results. In addition, their potential as design tools is explored by
introducing surface groups for enhancing CO2 capture; and finally, application
examples are presented for carbon dioxide capture from flue gases and for natural
gas purification, as well as in the separation of n-butane / iso-butane isomers
