Influences of pretreatment temperature on the surface silylation of diatomaceous amorphous silica with trimethylchlorosilane
Influences of pretreatment temperature on the surface silylation of diatomaceous amorphous silica with trimethylchlorosilane
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DOI：
10.1016/j.jnoncrysol.2006.05.035
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发表时间：
2006-10
影响因子：
3.5
通讯作者：
P. Yuan;Yang Dan;Zhongyu Lin;Hongping He;Xiaoyan Wen;Linjiang Wang;F. Deng
中科院分区：
文献类型：
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作者：
P. Yuan;Yang Dan;Zhongyu Lin;Hongping He;Xiaoyan Wen;Linjiang Wang;F. Deng
用三甲基氯硅烷（TMCS）对硅藻土无定形二氧化硅样品进行硅烷化改性。采用热重分析（TG）、1H魔角旋转核磁共振（1H MAS NMR）、傅里叶变换红外光谱（FTIR）和化学分析等方法对产物进行了表征。硅烷基化反应的程度随着硅烷基化前热处理温度的升高而增加。预处理温度的增加导致逐步去除物理吸附的水，然后通过与表面硅烷醇氢键结合的封端水的脱水，导致暴露越来越多的先前被水分子覆盖的孤立的和氢键结合的硅烷醇。在这些暴露的硅烷醇中，分离的硅烷醇显示出高的硅烷化反应活性，但氢键键合的硅烷醇显示出差的活性。在1100 ° C预处理的样品中，TMCS接枝到二氧化硅上的表面附着度最大（约1.81mmol TMCS基团/g二氧化硅），其中暴露的游离硅醇的量最大。所得的基础信息对深入了解白炭黑表面硅烷化反应及相关工业生产具有重要意义。
Diatomaceous amorphous silica samples were modified by silylation using trimethylchlorosilane (TMCS). The resultant materials were characterized by using thermogravimetry (TG),1H magic-angle spinning nuclear magnetic resonance (1H MAS NMR), Fourier transform infrared spectroscopy (FTIR) and chemical analysis. The degree of silylation was found to increase with the increasing temperature of thermal pretreatment on diatomaceous silica prior to silylation. Increment of the pretreated temperature leads to stepwise removal of physisorbed water followed by the dehydration of capping water that H-bonded with the surface silanols, resulting in exposure of more and more isolated and H-bonded silanols previously covered by water molecules. Among these exposed silanols, isolated silanols show high activity for silylation reaction but H-bonded ones show poor activity. The maximum degree of surface attachment of TMCS grafted onto the diatomaceous silica (about 1.81mmol TMCS groups per gram of silica) was shown in the sample pretreated at 1100°C, in which the amount of exposed isolated silanols get the maximum. The fundamental information derived from this work is of significance in well understanding the surface silylation reaction of diatomaceous silica and providing useful information for related industrial production.