【作者】 王知彩；

【导师】 高晋生；

【作者基本信息】 华东理工大学 ， 化学工艺， 2007， 博士

【摘要】 煤炭直接液化是解决石油短缺、保障能源供应安全的有效途径之一。提高煤的液化反应活性、缓和液化条件和增加油收率已成为当今煤直接液化领域的研究热点。本文以神华煤为原料,利用间歇式高压反应器研究了水热处理和溶胀处理对神华煤液化性能的影响。通过浸渍沉淀法制备了SO₄^2-/ZrO₂固体酸催化剂,利用FTIR、NH₃-TPD等分析技术及间歇式加氢液化试验,考察了制备条件对其结构、酸性和催化液化性能的影响,探讨了煤液化中新型固体酸的催化作用机理。此外,还研究了在该催化剂作用下的神华煤液化动力学,建立了相关模型。研究结果表明,热处理和水热处理能在一定程度上改变煤分子间的交联作用,尤其是非共价键作用形式和强度。较高温度下热处理时,伴随脱挥发分和热解反应,煤分子间产生了新的非共价键和共价键交联,热处理煤的溶胀和抽提性能低于原煤;适当温度的水热处理具有加氢作用,从而提高了处理煤CS₂/NMP混合溶剂抽提率和液化转化率,如250℃水处理煤液化转化率较原煤提高了6.3%。神华煤溶胀预处理研究表明:神华煤的主体为共价键结合的网络结构,以非共价键作用结合于煤分子主体结构中的小分子化合物含量较低;NMP和THN溶胀处理能够提高神华煤的CS₂/NMP混合溶剂抽提率和液化转化率。溶胀动力学研究表明,40～160℃范围内溶胀符合一级动力学方程,它们的表观活化能分别为0.77 KJ/mol和5.23 KJ/mol。对新型固体酸的研究表明:它对神华煤液化具有明显的催化活性,主要表现为对煤及其重质产物的催化裂解作用。其催化性能与强酸中心比例有关,酸性越强催化裂解能力越强,从而有利于煤大分子结构催化裂解,提高液化转化率。此外,SO₄^2-/ZrO₂也表现出较好的加氢作用。采用一种适宜条件制备的SO₄^2-/ZrO₂,在5MPa H₂、催化剂用量5%（wt）、400℃、30min等条件下,煤的转化率达到76.77%。此外,SiO₂负载SO₄^2-/Fe₂O₃的酸强度和催化性能类似于SO₄^2-/ZrO₂,且具有高的油气产率。神华煤加氢液化动力学研究表明:在375～450℃范围内,所建立的液化动力学模型能够较好地模拟神华煤液化动力学过程,其液化反应的速率常数介于0.2¹8.9×100 min^-1之间,表观活化能在90～145KJ/mol^-1范围内。同时,前沥青烯二次液化的动力学行为及液化产物的元素分析和¹H-NMR表征都进一步证明所建立的神华煤液化模型的合理性。更多还原

【Abstract】 Direct liquefaction of coal will be one of effective paths to compensate the shortage of petroleum sources and ensure the energy supplement. At present, it has becoming main research issues to improve the liquefaction reactivity of feed coal, to moderate the liquefaction conditions and increase the oil yield. Therefore, the aim of this dissertation is to research the pretreatment of feed coal and develop a novel solid acid with higher catalytic cracking activity in order to explore a high efficiency liquefaction technology under moderated conditions. Shenhua coal was used as a feedstock in this dissertation. The effects of hydrothermal treatment and swelling treatment on the hydro-liquefaction behavior of Shenhua coal were studied by the liquefaction experiment in a batch autoclave. Meanwhile, a series of SO₄^2-/ZrO₂ solid acids were prepared by precipitation and impregnation, and characterized by FTIR、NH₃-TPD techniques as well as batch hydro-liquefaction experiments. The impacts of the preparation conditions of catalyst on its structure, acidity and hydro-liquefaction properties were investigated. The catalytic liquefaction mechanism of solid acid was explored. In addition, the kinetics of the hydro-liquefaction of Shenhua coal was studied and a kinetic model was proposed.Results of thermal and hydrothermal pretreatments of Shenhua coal suggest that the cross-linking structure of Shenhua coal, especially the strength and distribution of non-covalent bonds such as hydrogen bond, were changed. The swelling ratio and extraction yield of thermal treated coal are lower than those of raw coal due to the formation of new non-covalent and covalent bond cross link in the process of thermal treatment under higher temperature, in which the devolatilization and the pyrolysis occured obviously. Because of obviously existing hydrogenation during hydrothermal treatment at certain temperature, the CS₂/NMP extraction yield and liquefaction conversion of Shenhua coal were improved. For example the conversion of treated coal at 250℃is 6.3% more than that of raw coal.The results of swelling pretreatment demonstrate that the principal structure of Shenhua coal consists of a large molecular network with covalent bond and the content of small molecular compounds bonding with non-covalent interactions is lower. The CS₂/NMP extraction yield and liquefaction conversion of Shenhua coal can be improved by swelling pretreatment with NMP or THN. The swelling kinetics studies suggest that the swelling process of Shenhua coal between 40℃and 160℃fits to a first order kinetic equation and the apparent activation energy of swelling in NMP and THN are respectively 0.77 KJ/mol and 5.23 KJ/mol.For the hydro-liquefaction of Shenhua coal, the SO₄^2-/ZrO₂ solid acid displays good catalytic activity, especially for the catalytic cracking of coal and its heavy products. Its catalytic activity on the coal liquefaction is related to the strength of acid site and the content of strong acid site. Strong acid site is favorable to catalyze the cracking of coal matrix and large molecular structural units, therefore increasing liquefaction conversion. In addition, the SO₄^2-/ZrO₂ solid acid shows also a good catalytic activity for the hydrogenation reactions. For the hydro-liquefaction of Shenhua coal, the optimal preparation conditions of SO₄^2-/ZrO₂ solid acid are 1 mol/l H2SO4 used as impragnant and calcination at 650℃for 3 hours. The conversion of Shenhua coal reached to 76.77%,when 5%（wt, to coal） SO₄^2-/ZrO₂ and 5.0 MPa H2 were used for the hydro-liquefaction under 400℃for 30min. In addition, the strength of acid site and catalytic properties of SO₄^2-/Fe₂O₃ loaded on SiO₂ are similar to SO₄^2-/ZrO₂, and it gives higher yield of oil+gas compared to that of SO₄^2-/ZrO₂ used as catalyst.The studies of hydro-liquefaction kinetics indicate that the proposed kinetic model is suitable to describe the hydro-liquefaction process of Shenhua coal catalyzed by solid acid between 375℃and 450℃. For all reactions in the model, the rate constants are in the range of 0.2¹8.9×100 min-1 and the apparent activation energies are in the range of 90～145KJ/mol-1. The hydro-liquefaction of preasphaltene and the element analyses and 1H-NMR spectra of liquefied products also further confirmed that this model is reasonable.更多还原