A Study On Theorganic Matter Structure Of Longkou Oil Shale By Selective Oxidation And The Effect Of Pyrolysis Temperature On The Structure

As the global energy resource consumption is increasing, and the traditional fossil energy is dwindling, it is more and more important to find the alternative energy resource and improve the efficiency of energy utilization. Oil shale is a kind of unconventional energy resources for oil and gas; due to its abundance, oil shale has become a very important alternative energy resource for the conventional fossil fuels. Oil shale is a kind of organic minerals, hence it can be directly burned and refined for oil by dry distillation, and it also can be used to produce chemicals. Our country is relatively abound with oil shale. Hence, the development of oil shale can effectively alleviate the lack of petroleum resource and the high crude oil dependency of our country.Oil shale is mainly composed of organic and inorganic minerals and the ash content of oil shale is extremely high. The organic matter in oil shale is mainly developed. It is well know that understanding the structure of the organic matter can improve the efficiency of oil shale applications. So, the research of oil shale organic matter has become the focus of many studies.The structure of oil shale has already extensively been studied through extraction, pyrolysis and oxidation methods, and a lot of structural characteristics and proposed structural models have been achieved. However, we found that twelve kinds of benzene carboxylic acids(BPCAs) could be obtained via selective oxidation of oil shale, and the present models could not reflect BPCAs yield distribution. In this work, BPCAs yield distribution was used to study the organic structure of oil shale. BPCAs yield distribution was obtained by selective oxidation of oil shale and used to construct the structure of aromatic clusters of oil shale organic matter, and combined with a variety of instrumental analysis results, a structural model of oil shale organic matter was built. In addition, this work also preliminarily studied the effect of pyrolysis temperature on the structure of oil shale organic matter via BPCAs yield distribution through selective oxidation of oil shale pyrolyzed at different temperatures. The main contents and conclusions are as follows.(1) The oxidation of Longkou(LK) oil shale was performed with catalytic oxidation method using NaVO3, NaOH-O2 oxidation method and KMnO4 oxidation method. In the catalytic oxidation, the effects of reaction temperature, time, initial oxygen pressure, H2SO4 mass and NaVO3/oil shale mass ratio on the oxidation product BPCAs yield and the yield distribution. It was found that these factors have obvious effect on the yield of BPCAs and a highest yield of 10.2 wt% could be obtained at conditions of a temperature of 180?, a reaction time of 30min, an initial 02 pressure of 4MPa, an oil shale content of 3.3%, a H2SO4 content of 1.7% and a mass ratio of NaVO3 to oil shale of 0.2. It was found that NaVO3and H2SO4 has a synergistic catalytic effect on the oxidation. In the NaOH-O2 oxidation, the effects of reaction temperature, time and NaOH/oil shale mass ratio on BPCAs yield were investigated. It was found that the factors had an obvious effect on the yield of BPCAs and a highest yield of 4.4 wt% was obtained. In the KMnO4 oxidation, two-step oxidation at 100? for 24h and 12h was performed, and eventually a BPCAs yield of 10.5 wt% was obtained.(2) Organic matter of LK oil shale was obtained by acid treatment to remove ash, and FTIR analysis of the organic matter was performed. It was found that the content of aliphatic structure was dominant, and the information of carboxyl group and aromatic ring function was obtained. Solid 13C NMR analysis of LK oil shale was performed, and the qualitative and quantitative information of different carbon groups was got, The structural parameters of LK oil shale are shown as follows:aromatic carbon ration is 18.2%,aliphatic carbon is 69.3%, branched chain alkyl is 10.9% and the average number of carbon chain is 10.8. XPS analysis was used to determine the present forms of N and S in LK oil shale, and the content of different forms of N and S was got. Phenolic hydroxyl and carboxyl groups in LK oil shale were determined experimentally, and they were 1.173 mmol/g and 1.125mmol/g, respectively.(3) Based on the above information, an organic matter structural model of LK oil shale was built. Firstly, the aromatic cluster structure was built based on the oxidation results,13C NMR analysis and elemental analysis. Then, the structural model of organic matter wasconstructedby adding aliphatic chain structure information from 13C NMR and structural parameters. The formula of the model isC1792H2650O264N26S17 and its molecular weight is 29327 amu.The model was evaluated with experiment results and analyses results and it was found that the deviation values were very small.(4) Longkou oil shalewas pyrolyzed at 200?,300?,400?,500? and 600?.The proximate and ultimate analysis of the pyrolysis productswere analyzed. It was found that volatile matter, moisture and ash content have an obvious changes with the pyrolysis temperature. The catalytic oxidation of pyrolysis products was performed to research the effect of oxidation reaction temperature on the yield of oxidation product BPCAs. A highest BPCAs yield of 8 wt% was obtained for pyrolysis products at 200? and 300?.A highest BPCAs yield of 12 wt% was obtained for pyrolysis products at 400?,14 wt% for 500?,and 18% for 600?.