Dynamics of CO2 molecules confined in the micropores of solids as studied by 13C NMR
Dynamics of CO2 molecules confined in the micropores of solids as studied by 13C NMR
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DOI：
10.1016/j.apsusc.2005.02.048
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发表时间：
2005-10
影响因子：
6.7
通讯作者：
H. Omi;T. Ueda;K. Miyakubo;T. Eguchi
中科院分区：
文献类型：
--
作者：
H. Omi;T. Ueda;K. Miyakubo;T. Eguchi
测定了co2吸附在几种多孔材料中的13c核磁共振与压力和温度的关系。对于CO2in活性炭纤维（ACF），在0 ~ 10MPa压力范围内观察到的光谱由两条线组成。在δ=126ppm处有一个非常尖锐的峰，归因于自由co2气体，而在δ=123ppm处有一个宽峰，归因于ACF微孔中受限制的co2分子，尽管在沸石和介孔二氧化硅等微孔材料中，co2只有一个峰归因于自由co2气体。在低压区，δ=123ppm的峰移至118ppm，出现了一个线宽约200ppm的非常宽的峰。这表明在ACF中存在两种不同分子运动速率的co2分子：一种是各向同性旋转，另一种是各向异性运动，即围绕与分子轴倾斜30°的轴旋转。这表明ACF微孔表面存在具有特征直径的小袋。
The pressure and temperature dependence of13C NMR of CO2adsorbed in several porous materials was measured. For CO2in activated carbon fiber (ACF), the spectrum observed in the pressure range from 0 to 10MPa consisted of two lines. A very sharp peak at δ=126ppm was attributed to free CO2gas and a broad peak at δ=123ppm was attributed to confined CO2molecules in the micropores of ACF, although CO2in microporous materials such as zeolites and mesoporous silica, gave only a single peak attributed to free CO2gas. In the low-pressure region, the peak at δ=123ppm shifted to 118ppm and a very broad peak with a line width of about 200ppm appeared. This indicates that there are two kinds of CO2molecules confined in ACF with different rates of molecular motion: one is undergoing isotropic rotation and the other is undergoing anisotropic motion, which rotates around an axis tilted by 30° from the molecular axis. This implies that small pockets with a characteristic diameter exist on the surface of the ACF micropore.