Study On Technology Conditions Of Supercritical Toluene Solvent Extraction Oil Shale Of Maoming

Owing to the global energy petroleum resources shortages and high oil prices, oil shale will be a special alternative for energy. Carbonization technology is often used in oil shale process to gain shale oil, but it shows some of disadvantages, including high cost for oil, complex process, low efficiency in conversion of energy and utilization of shale, serious pollution and difficult further process, which make carbonization of oil shale unfavorable when oil shale is used as alternative energy. It is necessary to develop a process which is both benign for environment and low in energy utilization cost. Solvent extraction is increasingly developed separation technology and can be used in oil shale process, which have high selectivity, well separation, and lower energy consumption. It is an important method of extracting the organic matter from oil shale. Significant oil shales mineral reserve exists in Maoming, Guangdong Province. Due to the shallow rock layer of oil shale, it is easy to exploit, with higher safety and low cost, which has great prospects for exploitation and utilization.Considering hotspot in related research field at home and abroad, exploitation and utilization status of oil shale from Maoming, Guangdong Province and relatively lack in related technology, extraction conditions of oil shale were compared and studied systematically, which is based on solvent extraction method. The effects of different process conditions on extraction rate of oil shale were discussed in detail. The major work and conclusions of paper are as follows:1. Through the industrial analysis, elemental analysis, aluminum retort analysis and ash element analysis of oil shale of Maoming, Guangdong Province, about7%oil yield of oil shale,36%carbon, and65%ash were obtained. Oil shale of Maoming has low carbon content, high ash content and low calorific value, which belongs to a high ash and low calorific value solid organic combustible mineral rock. And it is suitable for comprehensive utilization locally.2. Oil shale from Maoming was tested by extraction at80℃in experiment. Firstly, solvent for oil shale extraction was selected by single factor extraction at80℃and toluene was regarded to obtain the highest efficiency in extraction test. Secondly, some factors influenced extraction, e.g. particle size, volume of solvent oil shale and time for extraction, were investigated to optimize single factor. Thirdly, orthogonal experiments were finished with three-factor orthogonal experiment. The results in orthogonal experiments showed that conversion of oil shale was4.26%when100mesh of particle size,20mL/g of solvent,80℃of temperature and12hours of extraction were selected. Influence of particle size is significant.3. The optimum extraction conditions of Maoming oil shale under supercritical conditions with solvent extraction method were Studied. Under supercritical conditions, as solvent toluene, some factors influenced extraction, e.g. particle size, time, solid-liquid ratio, heating rate and temperature for extraction, were investigated to optimize single factor. Orthogonal experiments by supercritical toluene was tested to gain optimal conditions:100mesh of particle size,20:1of ratio of solvent and shale,10℃/min of rate for temperature,540℃of temperature and2hours of extraction, the conversion of oil shale was35.01%.The temperature for extraction significantly influenced conversion of shale and was regarded as important factor in all conditions selected.4. Characterization on both oil shale and its residue was carried out by infrared spectrometer and the result showed that small molecule was extracted by solvent and the extraction can give rise to structure change of shale pore. The results show that the solvent is mainly acting on small molecules in the solvent extraction process, leading to changes in the structure of the oil shale porosity.Compared with oil shale that can not be extracted, hydrocarbons and oxygenates is decreased in residue.5. Products from extraction by toluene were analyzed by GC-MS. The composition of products consists of hydrocarbons, oxygenates, nitrogen and compounds containing heteroatom, and hydrocarbons are predominant in products. The quantity of the mineral species of supercritical toluene extraction is dominant compared to the general category of atmospheric pressure80℃conditions. The supercritical toluene solvent extraction is expected to be an effective way of oil shale clean conversion and utilization.