Study On Pyrolysis Of Oil Shale Catalyzed By Transition Metal Salts

Energy, as an important material guarantee, is benefit for promoting the development of the world economy and human society. With the continuous consumption of energy, some problems have become more and more serious, for example energy shortage and the contradiction between energy supply and demand.So, it is urgent to search for the alternative energy so as to promote the sustainable development of human society. As a kind of non-conventional energy resources, oil shale has attracted wide attention from all over the world, since it has wide distribution and large reserves. Further, the increase of shale oil yield has become more important.The aim of this paper is focus on increasing yield of shale oil produced by oil shale pyrolysis. The catalytic pyrolysis behaviors of two kinds of oil shale?Huadian oil shale and Fushun oil shale? are studied. A quantitative study on the element content of oil shale is carried out by the mineralogy and geochemistry analysis methods in order to analyze the composition of the mineral and chemical composition of oil shale and to predict the composition characteristics of oil derived from oil shale pyrolysis.In addition, six transition metal salts are mixed with the oil shale sample for selecting the desired catalyst for oil shale pyrolysis. Catalytic effect of different transition metal salts is investigated by thermogravimetric analysis and thermal dynamic method. The influences of the retorting temperature, catalyst dosage and the blending ratio of cobalt chloride and manganese sulfate on shale oil yield and characteristics are also studied in order to determine the optimal application conditions, and the related reaction mechanisms are speculated. Besides, we also analyze the adsorption properties of two kinds of transition metal salts, systematically. The main research results are as follows:Firstly, mineralogical and geochemical characteristics of oil shale in Huadian and Fushun are analyzed based on the analysis methods of the mineralogy and geochemistry. The results show that the sedimentary environment is considered as an important factor influenced composition of the minerals in the oil shale. In Huadian oil shale, montmorillonite is dominating in the clay minerals and hematite shows high content in the heavy minerals. In Fushun oil shale, the main clay minerals and heavy minerals are kaolinite and illite, and siderite, respectively. Moreover, the analysis results of elements content of the oil shale samples indicate that the major element in the Huadian oil shale is SiO₂, followed by Ca O, Al₂O₃ and TFe₂O₃. Compared to that of Huadian oil shale, the SiO₂, Al₂O₃ and TFe₂O₃ content of Fushun oil shale is higher,while the Ca O content is lower than Huadian. The analysis results of trace elements and rare earth element contents in the oil shale show that Fushun has a higher degree of enrichment than that of Huadian oil shale. Besides, it is found that both oil shale samples have a large number of clay minerals?montmorillonite, kaolinite, illite, etc.?,which could produce some catalytic effects during oil shale pyrolysis. Due to chemical composition and structure, montmorillonite has strong surface adsorption capacity, inter layer adsorption capacity and ion exchange capacity. So, it is easy to form clay organic composite during oil shale pyrolysis, leading to the enhancement of catalytic effects. These results lay the foundation for future research work.Secondly, among six transition metal salts, cobalt chloride and manganese sulfate are considered as the desired catalysts for oil shale pyrolysis. Because of the addition of two catalysts, the initial temperature and the peak temperature corresponding to the maximum are significantly decreased and the apparent activation energy of oil shale also shows the downward trend. When the Co Cl2 addition is 1.0 %, the maximum shale oil yield is 23.25 % with the retorting temperature is 520 ?. Additionally, the analysis results of the obtained oil indicate that the addition of two transition metal salts is favorable to increase the aliphatic hydrocarbons content in oil. By comparing the catalytic effects of two kinds of transition metal salts with different blending ratios,the desired catalytic effect is obtained by the presence of pure cobalt chloride.At last, the influences of oil shale particle size, adsorption time, initial concentration and p H value on adsorption capacity of Co²⁺ and Mn²⁺ ion is studied.The experiment results show that the optimal adsorption time is 30 h for Co²⁺ and 60 h for Mn²⁺. The maximum adsorption capacity was 4766 ?g/g and 3026 ?g/g respectively. Furthermore, the calculation results of adsorption kinetics model and diffusion mechanism shows that adsorption process of catalysts is consistent with second-order kinetics, and the diffusion mechanisms are in consonance with Fickian diffusion mechanism and the diffusion mechanism.