用固体高分辨核磁共振研究煤结构Ⅰ.我国一些煤的结构特征

SOLID STATE~(13)C-NMR STUDY OF CHINESE COALS

用^(13)C CP/MAS 技术对我国十种不同变质程度的煤进行了研究,在这些煤样上完成了自旋晶格弛豫,变化接触时间和偶极去相实验。测定了质子自旋晶格弛豫时间 T_1~H,在旋转坐标中的质子自旋晶格弛豫时间 T_(1ρ)~H,交叉极化接触时间 T_(CH)和芳香、脂肪两个区域内的偶极去相时间T_G 和 T_L。将这些数据与标准的 CP/MAS 一起在精选的化学位移范围内积分可得到12个结构参数,令这些参数与煤中碳含量相关联,发现它们与煤的变质程度有密切关系。用 NMR 测定的桥碳数计算出每个煤样的芳香簇团大小,再根据计算的结果,设计出各种煤的芳香组结构模型。

Ten coals of different metamorphic degree have been investigated by the use of ^(13)C CP/MAS NMR technique,of which the spinlattice relaxation,variable contact time and dipolar dephasing experiments were performed on each coal.The data from above experi- ments,together with normal CP/MAS integration over selected chemical shift ranges,were used to derive 12 parameters of carbon skeletal structure including the aromaticity.These pa- rameters were correlated with carbon content(weight per cent)in coal and we found that close relation exists between the NMR parameters and metamorphic degree of coals.From the ratio of aromatic bridgehead to aromatic peripheral carbons as measured by NMR,the aromatic cluster size may be estimated for each coal.