运用吡啶吸附-拉曼光谱探测硅藻土表面酸位

The surface acid sites of diatomite detected by pyridine-Raman spectrometry

运用吡啶吸附 -拉曼光谱技术探测了硅藻土及其热处理产物的表面固体酸位。结果表明 ,室温下硅藻土表面羟基均为吸附水覆盖 ,不显B酸性 ,结构中也无能够接受电子对的Lewis酸位。经热处理后 ,某些酸性羟基脱水使硅藻土呈弱B酸性 ,B酸位浓度在经 650℃左右热处理后达到最大 ;另一方面 ,硅藻土中所含粘土矿物在 650℃左右因脱羟而发生结构变化 ,产生配位不饱和的Al位 。

In this study, pyridine_Raman spectrometry was used to study surface acid site properties of diatomite. In the experiment, the surface hydroxyl groups could not play the role of Brnsted acid sites without thermal treatment because they were all covered with water molecules,and there appeared no Lewis acid sites either. After being heated, some B acid sites appeared on diatomite surface, which originated from the surface acid hydroxyl groups that had desorbed water molecules, and the B acid sites reached the maximum quantity after being heated at some 650℃. Under the same treatment condition, L acid sites also appeared, and this was attributed to the structural deformation of clay minerals in diatomite.