| Coal, oil, gas and other conventional energy resources are the main energy in our country, which provide power for our society. But at present, the production and utilization of these resources are facing on many problems and challenges. Moreover, resources endowment and average possession of the energy are not high. Otherwise, energy is the insurance of a national economic development, and the demands for energy are increasing as the rapid economic growth, which needs us to accelerate the study of unconventional resources. At present, the reserves of the oil shale are the biggest in unconventional resources of our country, so it’s important to exploit this resource for alleviating the problem of conventional energy shortage. The organic compounds are the mother of the shale oil. The research on the characteristics of organic compounds in oil shale is the premise and fundament to realize the use of oil shale efficiently.The organic matter of oil shale is a complex macromolecule polymer. In order to obtain its structure, the oxidation degradation was used in this study. The structure of the macromolecule polymer was broken down into small molecules, which are easy to be detected. Then we backstepped the structure of raw material according to the structure of small molecule substance. In the present work, Yilan oil shale was oxidized in aqueous alkaline solution by oxygen. The product was detected and quantized via high performance liquid chromatography (HPLC). The results showed that twelve benzene polycarboxylic acids (BPCAs) and small molecules of fatty acids (SMFAs) were found. In order to obtain high yield of the BPCAs and SMFAs, we studied the effect of reaction temperature, pressure, time and the ratio of alkali to oil shale on the yield and distribution of oxidation products. The results showed that the yield of BPCAs could reach 13.6% and the total yield of SMFAs was as high as 43.1%, which provided a new way for the application of oil shale. What’s more, the distribution of BPCAs offered a reference for us to study the matrix structure of oil shale.The structure of organic matter was fractured thoroughly into small molecule compounds by the oxidation reaction under high temperature and high pressure. It is difficult to draw the organic structure of oil shale based on the oxidation products. To obtain more information about the organic structure of oil shale, we should keep the original structure of oil shale from damaging as less as possible. Here, we used composite solvents to extract small molecule substances from the demineralized oil shale and characterized the physical and chemical properties of oil shale using modern instruments. Combining with the results of previous experiments, we established the basic molecular model of Yilan oil shale in the end.In the extraction experiments, three composite solvents, NMP-CS2, cyclohexanone-NMP, and [Bmim]Cl-NMP, which were reported to have strong extraction ability, were chosen to extract the deashed oil shale. Extraction rates reached 7.32%,7.05% and 22.7% for NMP-CS2, cyclohexanone-NMP, and [Bmim]Cl-NMP respectively. It was found that the extracts contained fatty structure, aromatic structure and heteroatomic functional groups containing nitrogen, oxygen and sulfur through FTIR analyses. Moreover, long chain fatty hydrocarbon substances were detected via gas chromatography mass spectrometry (GC-MS). At the same time, modern analytical instruments were used to analyze the physical and chemical characteristics of Yilan oil shale. Scanning electron microscope (SEM) under different magnifications was used to obtain the surface morphology of oil shale. The results indicates that the surface showed flake structure and had tight, smooth layered rock phase structure, and the particle size was irregular. BET was used to test and analyze the size of the pore structure and specific surface area of oil shale. It was found that the pore distribution was non-uniform, which had slot hole through the accumulation of flake particle. In addition, surface areas of raw oil shale and deashed oil shale were 4.02 m2/g,8.70 m2/g respectively. The results indicate that the organic matter was released from the inorganic minerals after acid treatment. Using X-ray diffraction spectrum (XRD) to study the crystal phase structure and mineral species of oil shale, we found that organic matter of Yilan oil shale belongs to the amorphous material, which had not three-dimensional ordered crystal structure. Meanwhile, the main minerals of Yilan oil shale were silicate minerals and it also contained a small amount of kaolinite, calcite and white mica and so on. In order to make the average molecular structure model of organic matter more representatively, solid 13C nuclear magnetic resonance (NMR) were also carried out, by which the twelve kinds of structure parameters were obtained. It was found that carbon aromaticity was 54% and the mole fraction of aliphatic carbon was 41%. Integrating the above information, we finally obtained the basic structure model of Yilan oil shale. |
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