Structural characterization of Huadian oil shale kerogen by using 13C DP/MAS NMR

IF 1.3 4区工程技术 Q4 ENERGY & FUELS

Oil Shale Pub Date : 2021-01-01 DOI:10.3176/oil.2021.3.01

X. Han, X. Jiang, M. Mu, J. Shu, X. Wang, Y. You

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引用次数: 1

Abstract

. Quantitative 13 C direct polarization/magic angle spinning (DP/MAS) solid-state nuclear magnetic resonance (SSNMR) was used to characterize type I kerogen isolated from Huadian oil shale. The DP/MAS results showed that this kerogen was highly aliphatic and its aromaticity (f a ) was as low as 20.23%. The average aliphatic carbon chain length (Cn), average aromatic cluster size (C) and substitute degree of aromatic rings (σ) were calculated. The NMR-derived H/C and O/C atomic ratios (R H/C and R O/C ) obtained by DP were in agreement with the corresponding results of ultimate analysis, indicating the accuracy of DP for quantification. Besides, using varying contact times cross polarization (CP) spectra were obtained at the same MAS frequency as the DP spectrum. Regardless of contact time, the aromaticities derived from CP were much lower than that from DP. Consequently, the R H/C value from CP was significantly higher than that of ultimate analysis. The contribution of spinning sidebands could be ignored with the MAS frequency up to 10 kHz. It is concluded that DP with a high MAS frequency is necessary for gaining quantitative structural information about kerogen, especially for its molecular modeling.

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华甸油页岩干酪根13C DP/MAS NMR结构表征

．采用定量13c直接极化/魔角旋转(DP/MAS)固态核磁共振(SSNMR)技术对华甸油页岩ⅰ型干酪根进行了表征。DP/MAS结果表明，该干酪根为高脂肪族，芳香度(f a)低至20.23%。计算了平均脂肪碳链长(Cn)、平均芳香簇大小(C)和芳香环取代度(σ)。DP法得到的核磁共振H/C和O/C原子比(R H/C和R O/C)与最终分析结果一致，表明DP法定量的准确性。此外，采用不同的接触次数，在相同的MAS频率下获得了与DP光谱相同的交叉极化(CP)光谱。无论接触时间如何，CP的芳香性都远低于DP。因此，CP的R H/C值显著高于最终分析值。当MAS频率高达10 kHz时，自旋边带的贡献可以忽略。因此，高MAS频率的DP对于获得干酪根的定量结构信息，特别是对其分子建模是必要的。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Oil Shale 工程技术-工程：石油

CiteScore

2.90

自引率

15.80%

发文量

审稿时长

4.2 months

期刊介绍： The Oil Shale is a scientific-technical open access journal published by the Estonian Academy Publishers in collaboration with the University of Tartu, Tallinn University of Technology, and the Estonian University of Life Sciences.