Advancing computational analysis of porous materials – modelling three-dimensional gas adsorption in organic gels

Assessing the efficacy of specific porous materials for use in various applications has been a central focus for many experimental studies over the years, with a view to altering the material properties according to the desired characteristics. The application potential for one such class of nanoporous materials – organic Resorcinol-Formaldehyde (RF) gels – is of particular interest, due to their attractive and adjustable properties. In this work, we simulate adsorption analysis using lattice-based mean field theory, in both individual pores and within three-dimensional porous materials generated from a kinetic Monte Carlo cluster aggregation model. We investigate the impacts of varying pore size and geometry on the adsorptive behaviour, with results agreeing with those previously postulated in literature. The adsorption analysis is carried out for porous materials simulated with varying catalyst concentrations and solids contents, allowing their structural properties to be assessed from resulting isotherms, and the adsorption and desorption processes visualised using density colour maps. Isotherm analysis indicated that both low catalyst concentrations and low solids contents resulted in structures with open transport pores that were larger in width, whilst high catalyst concentrations and solids contents resulted in structures with bottle-neck pores that were narrower. We present results from both the simulated isotherms and pore size analysis distributions, in addition to results from RF gels synthesised in the lab and analysed experimentally, with significant similarities observed between the two. The results of this comparison not only validate the kinetic Monte Carlo model’s ability to successfully capture the formation of RF gels under varying synthesis parameters, but it also shows significant promise for the tailoring of material properties in an efficient and computationally inexpensive manner – something which would be pivotal in realising their full application potential, and could be applied to other porous materials whose formation mechanism operates under similar principles.