Propylsulfonic Acid-Functionalized Mesoporous Silica Synthesized by in Situ Oxidation of Thiol Groups under Template-Free Condition
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- 作者：Xueguang Wang ; Soofin Cheng ; Jerry C. C. Chan
- 刊名：Journal of Physical Chemistry C
- 出版年：2007
- 出版时间：February 8, 2007
- 年：2007
- 卷：111
- 期：5
- 页码：2156 - 2164
- 全文大小：194K
- 年卷期：v.111,no.5(February 8, 2007)
- ISSN：1932-7455
文摘
Propylsulfonic acid-functionalized mesoporous silica was prepared through in situ oxidization of mercaptopropylgroups with H2O2 during a template-free condensation of tetraethyl orthosilicate (TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) under strong acidic condition. The obtained materials with 3-15 mol %loadings of sulfonic acid groups had surface areas up to 700 m2/g and pore sizes around 3.5 nm. The materialssynthesized with TEOS prehydrolysis had larger surface areas, pore volumes, and average pore diametersthan those synthesized without TEOS prehydrolysis. IR, TG, solid-state NMR, and S K-edge XANES analysesshowed that all the mercaptopropyl groups were completely converted to propylsulfonic acid groups withoutdecomposition of the organic moieties using H2O2 as the in situ oxidant in the synthesis procedure. Theaccessibilities of sulfonic acid centers were determined by ion-exchange with cations of various sizes. Thefunctionalized materials were used as acid catalysts in esterification of acetic acid with methanol andacetalization of chlorobenzaldehyde with methanol. The results showed that the propylsulfonic acid-functionalized mesoporous silica prepared with TEOS prehydrolysis and in situ oxidation had similar catalyticactivities as propylsulfonic acid-functionalized SBA-15 but higher than the counterparts synthesized withoutTEOS prehydrolysis or by postoxidation of mercaptopropyl groups with H2O2.