(520e) Advanced Characterization of Disordered Mesoporous Solids

Mesoporous solids have found wide uses in catalysis, adsorption, molecular separations, gas and energy storage, among others. Indeed, precise structure-function relations of guest molecules in pores are rightly obtained when accurate knowledge of the confining space is available. At present, most approaches for pore characterization consider disordered porous materials as individual collection of pores where fluid phase transition occurring in one pore has no effect on adjacent pores. However, pore interconnectivity renders fluid phase behavior in one pore dependent on the phase state in its neighboring pore.

We show systematically how a model of statistical chain of pores can be applied for solid-liquid phase transitions of porous solids. By creating a kernel-based
approach incorporating a variable non-frozen layer thickness between solid core and pore wall and eliminating any a priori assumption of phase transition
occurring by metastable or equilibrium transition, we refine the thermoporometry characterization technique.

For verification, we show how this approach works well with ordered materials
like MCM-41 porous silica and reveals disorder in SBA-15 materials. This
approach can be extended to other phase transition phenomena such as gas
adsorption.

References
[1] Schneider D.; Kondrashova D.; Valiullin R., 2017, “Phase transitions in
disordered mesoporous solids”, Scientific Reports, 7, 7216.
[2] Schneider, D. and Valiullin R., 2019, “Capillary condensation and evaporation
in irregular channels: Sorption isotherm for serially connected pore model”,
Journal of Physical Chemistry C, 123, 16239.
[3] Enninful H.R.N.B., Schneider D., Hoppe A., König S., Fröba M., Enke D. and
Valiullin R., 2019, “Comparative gas sorption and cryoporometry study of
mesoporous glass structure: Application of the serially connected pore model”, Frontiers in Chemistry, doi: 10.3389/fchem.2019.00230.
[4] Enninful H.R.N.B., Schneider D., Kohns R., Enke D. and Valiullin R., 2020, “A
novel approach for advanced thermoporometry characterization of mesoporous
solids: Transition kernels and the serially connected pore model”, Microporous
and Mesoporous Materials 309, 110534.
[5] Enninful H.R.N.B., Schneider D., Enke D. and Valiullin R., 2021, “Impact of
Geometrical Disorder on Phase Equilibria of Fluids and Solids Confined in
Mesoporous Materials”, Langmuir, 37, 3521-3537.