Details
| Original language | English |
|---|---|
| Pages (from-to) | 95-100 |
| Number of pages | 6 |
| Journal | Microporous and Mesoporous Materials |
| Volume | 116 |
| Issue number | 1-3 |
| Publication status | Published - 1 Apr 2008 |
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
ASJC Scopus subject areas
- Chemistry(all)
- General Chemistry
- Materials Science(all)
- General Materials Science
- Physics and Astronomy(all)
- Condensed Matter Physics
- Engineering(all)
- Mechanics of Materials
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In: Microporous and Mesoporous Materials, Vol. 116, No. 1-3, 01.04.2008, p. 95-100.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - The Sears number as a probe for the surface chemistry of porous silicas
T2 - Precipitated, pyrogenic and ordered mesoporous silicas
AU - Heinroth, Falk
AU - Münnekhoff, Reimar
AU - Panz, Christian
AU - Schmoll, Ralf
AU - Behnisch, Jürgen
AU - Behrens, Peter
PY - 2008/4/1
Y1 - 2008/4/1
N2 - 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.
AB - 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.
KW - Ordered mesoporous silicas
KW - Precipitated silicas
KW - Pyrogenic silicas
KW - Sears number
KW - Silica
KW - Silinol groups
UR - http://www.scopus.com/inward/record.url?scp=53949112699&partnerID=8YFLogxK
U2 - 10.1016/j.micromeso.2008.03.022
DO - 10.1016/j.micromeso.2008.03.022
M3 - Article
AN - SCOPUS:53949112699
VL - 116
SP - 95
EP - 100
JO - Microporous and Mesoporous Materials
JF - Microporous and Mesoporous Materials
SN - 1387-1811
IS - 1-3
ER -