Influence of silica structure on its dehydration

Authors

  • Андреас Георг Томе Thomé Andreas Georg– PhD student, Department of Industrial Chemistry 2, Institute of Chemistry, Carl von Ossietzky University, Oldenburg, Germany, е-mail: andreas.georg.thome@uni-oldenburg.de
  • Т. Н. Нефедова Nefedova Tatiana N. – senior researcher SRC "Fundamental research in the fields of natural and building science", Voronezh State Technical University, Voronezh, Russia; Postdoctoral Researcher at Department of Industrial Chemistry 2, Institute of Chemistry, Carl von Ossietzky University, Oldenburg, Germany, e-mail: TNephedova@gmail.com
  • Франк Шретер Schroeter Frank – M.sc. student, Department of Industrial Chemistry 2, Institute of Chemistry, Carl von Ossietzky University, Oldenburg, Germany, е-mail: frank.schroeter@uni-oldenburg.de
  • В. Ф. Селеменев Selemenev Vladimir F.– professor, the head the department of Analytical Chemistry, faculty of Chemistry, Voronezh State University, Voronezh, Russia, e-mail: common@chem.vsu.ru
  • Франк Ресснер Roessner Frank – professor, head of the Department of Industrial Chemistry 2, Institute of Chemistry, Carl von Ossietzky University, Oldenburg, Germany; e-mail: frank.roessner@uni-oldenburg.de

DOI:

https://doi.org/10.17308/sorpchrom.2017.17/434

Keywords:

dehydration, silica, MCM-41, SBA-15, H-magadiite, silicalite, silica gel, DRIFT- spectroscopy

Abstract

The influence of structure of the different silica modifications – МСМ-41 (ordered mesoporous), SBA-15 (ordered micro-mesoporous), Н-magadiite (layered), silicalite (microporous) and silica gel (amorphous, porous) – on their dehydration was studied by «in situ» DRIFT- spectroscopy under heating of samples. The textural properties of the samples were obtained by means of N2- physisorption. The pore volume and pore diameter were calculated by the BJH method. The surface area was determined in according to BET.

Several species on the silica surface were identified: hydrogen bonded vicinal and terminal silanol groups. Their interaction with water molecules results in the broad band of OH-stretching vibration poor resolved in dependence on the studied samples. Noteworthy, that in case of layered H-magadiite hydroxyl groups located in the interlayer space were identified. Their strong interaction results in a shrinking of the basal distance between the layers as detected by measuring the accessible surface using BET. It is also reflected in the high intensity of OH-stretching vibration of hydrogen bonded silanol groups. 

It was established, that the dehydration of the different forms of silica includes three stages: (i) desorption of physisorbed water, (ii) decomposition of hydrogen bonded silanol groups accompanied by the increase of intensity of the free silanol groups (3740 cm-1) and (iii) their dehydroxylation. Principle of the dehydration process does not depend on the structural features of the investigated silica modifications but it differs only in the temperature ranges of the dehydration stages.

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Published

2018-02-22

Issue

Vol. 17 No. 5 (2017): Sorption and chromatographic processes

Section

Статьи

How to Cite

Influence of silica structure on its dehydration. (2018). Sorbtsionnye I Khromatograficheskie Protsessy, 17(5), 741-749. https://doi.org/10.17308/sorpchrom.2017.17/434

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