IR study of hydroxylated silica
IR study of hydroxylated silica
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DOI：
10.1021/la00078a014
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发表时间：
1987-11
期刊：
影响因子：
3.9
通讯作者：
S. Zhdanov;L. Kosheleva;T. Titova
中科院分区：
文献类型：
--
作者：
S. Zhdanov;L. Kosheleva;T. Titova
通过分析比表面积范围为 1 至 1000 m2 的各种无定形和结晶二氧化硅（例如石英纤维 (QF)、硅胶、气相二氧化硅和硅沸石）的 FT-IR 光谱，证明了红外傅立叶光谱对研究各种化合物吸附到二氧化硅表面时发生的表面模式和分子相互作用的贡献。因此，Si-OH··-Si发现硅烷醇基团对代表高度羟基化的无定形二氧化硅表面的氢扰动的硅烷醇基团，其在室温下引发脱水和/或脱羟基过程。比表面积为 1-5 m2 g-1 的“疏水”QF 的微孔性和表面渗透性导致 QF 对分子吸附水的顽强保留，这取决于 QF 的化学修饰。如果有的话，硅沸石的亲水位点主要由残留的碱金属阳离子表示。在硅沸石的合成过程中，少量三乙胺吸附在无定形超纯二氧化硅表面上，会导致与 Si-OH 基团发生不同强度的酸碱型相互作用，直至形成在真空温度超过 773 K 下稳定的表面化合物 (Et3HN)+(Si-0)~。
The contribution of IR Fourier spectroscopy to theinvestigation of the state of surfacemodes and molecular interactions occurring on adsorption of various compounds onto silicasurfaces was demonstrated by the analyses of the FT-IR spectra of various amorphous and crystalline silicas with specific surface area ranging from 1 to 1000 m2 3456789101112g" 1, such as quartz fiber (QF), silica gel, aerosil, and silicalite. Thus, the Si-OH··-Si silanol group pairs were found to represent those H-perturbed silanolgroups of highly hydroxylated amorphous silica surfaces which initiate dehydration and/or dehydroxylation processes at room temperatures. Microporosity and surface permeability of “hydrophobous” QF with a specific surface area of 1-5 m2 g-1 cause a tenacious retention by QF of molecular adsorbed water varied on chemical modifications of QF. Hydrophilic sites of silicalites, if any, are largely represented by residual alkali cations being doped on synthesis of silicalite. Adsorption of small amounts of triethylamine onto amorphous superpure silica surfaces causes acid-base type interactions of varying strength with Si-OH groups up to the formation of a surface chemical compound (Et3HN)+(Si-0)~ stable under vacuum to over 773 K.