抚顺油页岩热解成烃机理——固体^(13)C核磁波谱技术的应用

HYDROCARBON FORMATION MACHANISM OF FUSHUN OIL SHALE DURING PYROLYSIS——A STUDY WITH SOLID STATE ^(13)C NMR SPECTROSCOPIC TECHNIQUES

用高场(75.46MHz)固体^(13)C NMR波谱仪研究了抚顺油页岩在不同终温下热解时油母质的化学结构变化。在应用交叉极化魔角旋转技术的同时,采用了旋转边带全抑制技术,取得了高分辨的波谱;采用偶极相移技术,取得了带质子与不带质子碳的定量数据;又采用了旋转边带分析技术,取得了高芳碳含量油母质中芳碳的结构组成信息。由此得出了热解过程中不同结构的碳分布与芳碳率、芳氢率、芳氢取代率、未取代芳核假想氢碳比等结构参数。据此,对油页岩油母质的热解成烃机理进行了讨论。

Fushun oil shale was pyrolysed in a Fischer assay with different final temperatures (400～510℃). The kerogen concentrates demineralized from solid residues by HCl and HF treatment were analyzed using a high field (75.46 MHz) solid state ^(13)C NMR spectrometer. In addition to the NMR spectra of CP/MAS, the spinning sidebands of aromatic carbon were suppressed with TOSS technique of Dixon. Dipolar dephasing technique was employed to measure the protonated and nonprotonated carbons. For the samples of high aromaticity, application of spinning sideband analysis distinguished four different types of aromatic carbons. Data from these ^(13)C NMR techniques depicted a detailed carbon distribution of Fushun oil shale kerogen and its evolution feature. It also derived a series of kerogen structural parameters with key importance including carbon and hydrogen aromaticity, substitutionality of aromatic hydrogen and hypothetical H/C of unsubstituted aromatic cluster. In the light of these results, the mechanism of hydrocarbon formation during pyrolysis process is discussed.