SURFACE FUNCTIONALITY OF AMORPHOUS SILICA BY INFRARED SPECTROSCOPY
SURFACE FUNCTIONALITY OF AMORPHOUS SILICA BY INFRARED SPECTROSCOPY
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DOI：
10.1021/j150568a004
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发表时间：
1958-01-01
影响因子：
--
通讯作者：
MCDONALD, RS
中科院分区：
文献类型：
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作者：
MCDONALD, RS
本文在2800 ~ 4000 cm -1光谱范围内，研究了malinckrodt特殊块状硅酸（纯沉淀二氧化硅）和Cabosil（纯气相二氧化硅）表面硅醇基团的高分辨率红外光谱。结果表明，二氧化硅表面的羟基以几种不同的状态存在，它们在红外波段的吸收频率或多或少不同。在这些频率的测量已经被用来研究不同类型的羟基在不同条件下的行为。沉淀二氧化硅表面上的硅烷醇基团主要是氢键，而气相二氧化硅表面上的硅烷醇基团主要是分离的。在真空940下脱气8小时后，两种二氧化硅表面仍有相当数量的分离硅醇基团，但未检测到氢键基团。在脱气过程中，表面硅烷醇基团的吸收带变得更窄，并向更高的频率转移，这表明脱气过程中被破坏的硅烷醇基团与脱气后保留的硅烷醇基团的环境有明显不同。脱气过程中硅醇基的破坏产生了活性表面位点，这些活性表面位点在室温下与水蒸气迅速反应，再生出氢键硅醇基。
Infrared spectra of silanol groups on the surface of Mallinckrodt Special Bulky Silicic Acid, a pure precipitated silica, and Cabosil, a pure fumed silica, nave been studied under high resolution in the region of the spectrum between2800 and 4000 cm.-1. The results indicate that hydroxyl on the surface of silica exists in several different states which absorb at more or less distinct frequencies in the infrared. Measurements at these frequencies have been used to study the behavior of the different types of hydroxyl group under various conditions. Silanol groups on the surface of the precipitated silica are shown to be predominantly hydrogen bonded, while those on the surface of the fumed silica are shown to be predominantly isolated. After degassing at 940 in vacuo for 8 hours, appreciable amounts of isolated silanol groups remained on the surface of both silicas, but no hydrogen bonded groups were detected. During degassing, the absorption band of surface silanol groups became much narrower and shifted to higher frequency, indicating that thesilanol groups which were destroyed during degassing had an appreciably different environment from those which remained, after degassing. Destruction of silanol groups during degassing produced active surface sites which reacted rapidly with water vaporat room temperature to regenerate hydrogen bonded silanol groups.