用^(13)C-NMR的DEPT技术研究减压渣油的平均结构

STUDY ON THE AVERAGE STRUCTURE OF RESIDUES BY DEPT ^(13)C-NMR

对大庆、胜利、孤岛、欢喜岭四种原油的减压渣油及其各组份,用^(13)C-NMR的DEPT技术测得其平均结构中—CH、—CH_2、—CH_3各基团的含量。并将其与用红外光谱法测得的数值进行对比,发现就多数样品而言两者比较接近。据此计算得到的平均链长参数C_p/nCH_3比较合理,能反映不同样品在这方面的结构特征。同时,还对各种求取芳碳率f_A的方法进行了对比讨论。结果表明,在大多数情况下,用^(13)3C-NMR法、~1H-NMR法及经验公式法求得的f_A值比较接近,而用密度法算得的结果则偏差较大。

The contents of the —CH_3,—CH——2,—CH groups in the vacuum residues of Daqing,Shengli,Gudao and Huanxiling crudes have been determined directly by the DEPT ^(13)C-NMR method.For most samples,the ratios nCH_2/nCH_3 obtained by DEPT are near to those correlated from the relative intensities of the 1460cm^(-1)and 1380cm^(-1)bands in the IR spectra.By DEPT,the structural parameter C_p/nCH_3 can be obtained to characterize the average chain length of the samples.The aromaticities of the samples have been calculated by different methods.It is shown that the f_A calculated based on ~1H-NMR are very near to that obtained by ^(13)C-NMR.The Brown-Lader's assumption,x=y=2,is confirmed by DEPT as well.