TY - JOUR

T1 - Drying of Hierarchically Organized Porous Silica Monoliths–Comparison of Evaporative and Supercritical Drying

AU - Kohns, Richard

AU - Torres-Rodríguez, Jorge

AU - Euchler, Daniel

AU - Seyffertitz, Malina

AU - Paris, Oskar

AU - Reichenauer, Gudrun

AU - Enke, Dirk

AU - Huesing, Nicola

N1 - Publisher Copyright: © 2023 by the authors.

PY - 2023/1/16

Y1 - 2023/1/16

N2 - In this study, we present a detailed comparison between a conventional supercritical drying process and an evaporative drying technique for hierarchically organized porous silica gel monoliths. These gels are based on a model system synthesized by the aqueous sol–gel processing of an ethylene-glycol-modified silane, resulting in a cellular, macroporous, strut-based network comprising anisotropic, periodically arranged mesopores formed by microporous amorphous silica. The effect of the two drying procedures on the pore properties (specific surface area, pore volume, and pore widths) and on the shrinkage of the monolith is evaluated through a comprehensive characterization by using nitrogen physisorption, electron microscopy, and small-angle X-ray scattering. It can clearly be demonstrated that for the hierarchically organized porous solids, the evaporative drying procedure can compete without the need for surface modification with the commonly applied supercritical drying in terms of the material and textural properties, such as specific surface area and pore volume. The thus obtained materials deliver a high specific surface area and exhibit overall comparable or even improved pore characteristics to monoliths prepared by supercritical drying. Additionally, the pore properties can be tailored to some extent by adjusting the drying conditions, such as temperature.

AB - In this study, we present a detailed comparison between a conventional supercritical drying process and an evaporative drying technique for hierarchically organized porous silica gel monoliths. These gels are based on a model system synthesized by the aqueous sol–gel processing of an ethylene-glycol-modified silane, resulting in a cellular, macroporous, strut-based network comprising anisotropic, periodically arranged mesopores formed by microporous amorphous silica. The effect of the two drying procedures on the pore properties (specific surface area, pore volume, and pore widths) and on the shrinkage of the monolith is evaluated through a comprehensive characterization by using nitrogen physisorption, electron microscopy, and small-angle X-ray scattering. It can clearly be demonstrated that for the hierarchically organized porous solids, the evaporative drying procedure can compete without the need for surface modification with the commonly applied supercritical drying in terms of the material and textural properties, such as specific surface area and pore volume. The thus obtained materials deliver a high specific surface area and exhibit overall comparable or even improved pore characteristics to monoliths prepared by supercritical drying. Additionally, the pore properties can be tailored to some extent by adjusting the drying conditions, such as temperature.

KW - ambient pressure drying

KW - evaporative drying

KW - silica monolith

KW - supercritical drying

UR - http://www.scopus.com/inward/record.url?scp=85146698022&partnerID=8YFLogxK

U2 - 10.3390/gels9010071

DO - 10.3390/gels9010071

M3 - Article

AN - SCOPUS:85146698022

VL - 9.2023

JO - Gels : open access physical and chemical gels journal

JF - Gels : open access physical and chemical gels journal

SN - 2310-2861

IS - 1

M1 - 71

ER -