The hydroxyl species and acid sites on diatomite surface: a combined IR and Raman study
The hydroxyl species and acid sites on diatomite surface: a combined IR and Raman study
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DOI：
10.1016/j.apsusc.2003.10.031
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发表时间：
2004-04
影响因子：
6.7
通讯作者：
P. Yuan;D. Wu;Hongping He;Z. Lin
中科院分区：
文献类型：
--
作者：
P. Yuan;D. Wu;Hongping He;Z. Lin
用漫反射红外傅里叶变换光谱（DRIFT）、吡啶吸附分子的拉曼光谱（Py-拉曼）和原位Py-IR研究了吡啶表面的羟基和酸中心。鉴定了刘易斯（L）和布朗斯特（B）酸位点，以及各种羟基物质，包括分离的羟基、H-键合的羟基和物理吸附的水。粘土样品中的L酸位主要来源于粘土杂质，而B酸位主要来源于中等强度的羟基。在室温下，无论是孤立的和H-键合的硅醇与物理吸附的水通过氢键缔合。煅烧处理后，硅醇上的物理吸附水会脱附，随着温度的升高，硅醇会发生缩合反应。通常，氢键键合的硅烷醇比孤立的硅烷醇更容易缩合。白炭黑的表面羟基物种的性质与沉淀白炭黑而不是气相白炭黑更相似。
Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), Raman spectroscopy of adsorbed pyridine molecules (Py-Raman) and in situ Py-IR have been used to investigate the hydroxyl species and acid sites on diatomite surfaces. The Lewis (L) and Brønsted (B) acid sites, and various hydroxyl species, including isolated hydroxyl groups, H-bonded hydroxyl groups and physically adsorbed water, are identified. The L acid sites in diatomite samples are resulted from the clay impurities, and the B acid sites are resulted from some moderate strength H-bonded hydroxyl groups. At room temperature, both of the isolated and H-bonded silanols associate with the physically adsorbed water by hydrogen bond. After calcination treatment, physically adsorbed water will be desorbed from the silanols, and the silanols will condense with the increase of temperature. Generally, the H-bonded silanols condense more easily than the isolated ones. The properties of surface hydroxyl species of diatomaceous silica are more similar to precipitated silica rather than fumed silica.