The Sears number as a probe for the surface chemistry of porous silicas

Precipitated, pyrogenic and ordered mesoporous silicas

verfasst von: Falk Heinroth, Reimar Münnekhoff, Christian Panz, Ralf Schmoll, Jürgen Behnisch, Peter Behrens
Abstract: In 1956, Sears had introduced a simple empirical method to determine the surface area of colloidal silicas. This technique consists in the titration of silanol groups using sodium hydroxide solution and relies on the assumption that the silanol group density is constant. When porosimetric methods became more easily accessible and automated, this simple method for the determination of surface areas appeared obsolete. The Sears number was then further developed by industry as an indicator for the hydrophilicity of a silica material. As a rather simple empirical method, the Sears number is directly related to practical aspects of the application of a silica material in an aqueous environment, as it determines the number of silanol groups accessible for chemical reactions. Here, we describe the adaptation of the Sears number concept to ordered mesoporous silicas (SBA-15, SBA-16, MCM-41 and MCM-48) and show that with the method presented here, reproducible and useful results can be obtained. Due to their high surface areas, mesoporous materials have very high Sears numbers when compared to industrially fabricated precipitated and pyrogenic silicas.
Organisationseinheit(en): Institut für Anorganische Chemie
Externe Organisation(en): Evonik Degussa GmbH
Typ: Artikel
Journal: Microporous and Mesoporous Materials
Band: 116
Seiten: 95-100
Anzahl der Seiten: 6
ISSN: 1387-1811
Publikationsdatum: 01.04.2008
Publikationsstatus: Veröffentlicht
Peer-reviewed: Ja
ASJC Scopus Sachgebiete: Allgemeine Chemie, Allgemeine Materialwissenschaften, Physik der kondensierten Materie, Werkstoffmechanik
Elektronische Version(en): https://doi.org/10.1016/j.micromeso.2008.03.022 (Zugang: Unbekannt)

BibTeX

@article{a920e1a9f8f344dc93603ba4b685400e,
title = "The Sears number as a probe for the surface chemistry of porous silicas: Precipitated, pyrogenic and ordered mesoporous silicas",
abstract = "In 1956, Sears had introduced a simple empirical method to determine the surface area of colloidal silicas. This technique consists in the titration of silanol groups using sodium hydroxide solution and relies on the assumption that the silanol group density is constant. When porosimetric methods became more easily accessible and automated, this simple method for the determination of surface areas appeared obsolete. The Sears number was then further developed by industry as an indicator for the hydrophilicity of a silica material. As a rather simple empirical method, the Sears number is directly related to practical aspects of the application of a silica material in an aqueous environment, as it determines the number of silanol groups accessible for chemical reactions. Here, we describe the adaptation of the Sears number concept to ordered mesoporous silicas (SBA-15, SBA-16, MCM-41 and MCM-48) and show that with the method presented here, reproducible and useful results can be obtained. Due to their high surface areas, mesoporous materials have very high Sears numbers when compared to industrially fabricated precipitated and pyrogenic silicas.",
keywords = "Ordered mesoporous silicas, Precipitated silicas, Pyrogenic silicas, Sears number, Silica, Silinol groups",
author = "Falk Heinroth and Reimar M{\"u}nnekhoff and Christian Panz and Ralf Schmoll and J{\"u}rgen Behnisch and Peter Behrens",
year = "2008",
month = apr,
day = "1",
doi = "10.1016/j.micromeso.2008.03.022",
language = "English",
volume = "116",
pages = "95--100",
journal = "Microporous and Mesoporous Materials",
issn = "1387-1811",
publisher = "Elsevier BV",
number = "1-3",
}