离子液体萃取及氧化萃取脱硫研究
文献类型：学位论文
| 作者 | 高红帅 |
| 学位类别 | 博士 |
| 答辩日期 | 2010-01-21 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 过程工程研究所 |
| 导师 | 刘会洲 |
| 关键词 | 离子液体 萃取脱硫 柴油 二苯并噻吩(DBT) 萃取氧化耦合 固定化 微胶囊 |
| 其他题名 | Studies on Desulfurization of Fuel by Extraction and Oxidative Extraction with |
| 学位专业 | 化学工艺 |
| 中文摘要 | 随着环保法规和燃料油质量标准的日益严格，必须开发经济、有效的燃料油深度脱硫新技术。离子液体萃取脱硫具有操作简便、能耗低、不易造成环境污染和溶剂可以循环使用等方面的优点，离子液体不仅可以作为萃取剂而且也可以作为催化剂，有望成为传统加氢脱硫(HDS)的辅助技术。本论文从离子液体的设计和固定化等方面入手，开展了咪唑类、吡啶类离子液体萃取及氧化萃取脱硫研究。 制备了[BMIM][BF4]，[BMIM][PF6]，[HMIM][BF4]，[HMIM][PF6]和[BMIM][FeCl4] 5种咪唑类离子液体，考察了它们的结构对脱硫性能的影响。对于脱硫率的影响，4种中性离子液体阳离子起主导作用，随着离子液体的烷基链增长，离子液体阳离子的π电子密度越大，与含硫化合物之间相互作用越强，脱硫率升高；[BMIM][FeCl4]是路易斯酸性离子液体，对水和空气稳定，它与芳香性含硫化合物之间通过酸碱相互作用和π-络合相互作用进一步提高其脱硫率；同时[BMIM][FeCl4]路易斯酸性离子液体可通过正己烷反萃再生。 设计合成一系列吡啶类离子液体，通过改变阳离子尺寸的大小，详细考察了离子液体的结构以及含硫化合物的种类对脱硫性能的影响。对于模拟油相中的含硫化合物，所研究的吡啶类离子液体对它们的脱硫能力为 [C4Py][BF4] < [C6Py][BF4] < [C8Py][BF4] < [C43MPy][BF4] < [C43,5DMPy][BF4] < [C63MPy][BF4] < [C83MPy][BF4] < [C63,5DMPy][BF4] < [C83,5DMPy][BF4]；而对于每一种离子液体，由于含硫化合物芳香环上的π电子云密度差异以及4, 6-DMDBT硫化合物4位和6位上取代甲基的空间位阻效应，4种含硫化合物被脱除的难易程度为4, 6-DMDBT < TS < BT < DBT或TS < 4, 6-DMDBT < BT < DBT。萃取脱硫的驱动力既有吡啶环上的π电子与芳香性含硫化合物π电子之间的π-π相互作用，同时由于离子液体分子结构较大，部分有机硫分子插入到离子液体动态的分子结构中，形成液相格状包合物。该类离子液体的脱硫效果要优于咪唑类离子液体，而且通过加水稀释的方法可以实现离子液体的再生。 为了克服离子液体粘度高、使用中流失等问题，利用喷射悬浮分散装置制备了离子液体微胶囊。获得理想微胶囊的最佳压力为0.20 MPa，最佳距离是喷嘴被恒定在距水相液面20 cm处。理想的溶剂为二氯甲烷，壁材为聚砜，分散剂为明胶。制备的离子液体微胶囊粒径分布均匀，表面光滑，粒径大小约为70 µm，包覆率达29%。由于离子液体被紧密的包覆，与游离状态的离子液体相比，其脱硫性能仍需提高。该装置亦可以用于其他种类离子液体微胶囊的制备。 为了改善离子液体作为萃取剂脱硫率低的问题，设计了[BMIM][FeCl4]，[BMIM][HSO4]和[C4Py][HSO4] 3种离子液体同时作为萃取剂和催化剂，进行了萃取与氧化耦合脱硫研究。对于[BMIM][FeCl4]萃取氧化耦合体系，反应10 min时脱硫率达93.2%；对于[BMIM][HSO4]离子液体萃取氧化耦合体系，在Vmodel oil /VIL = 2:1，O/S=5，室温的条件下，反应90 min 基本达到萃取氧化平衡，脱硫率为99.6%，对含硫化合物脱硫选择性顺序为DBT > BT > TS > 4,6-DMDBT。该类体系在室温下进行，比较方便，脱硫率高，有望成为高效、绿色的柴油超深度脱硫技术。 |
| 英文摘要 | With the more and more stringent environmental regulations and improvement of fuel oil quality, refiners are facing challenges to develop new economical and efficient methods for removal of aromatic sulfur compounds. The extractive desulfurization (EDS) process using ionic liquids (ILs) serving as extractant and acting as catalyst can be a complementary technology for the hydrodesulfurization (HDS) process, which is simple, less energy needs, and the ILs can be recycled. The purpose of this thesis is to develop a process of desulfurization of fuel by extraction and oxidative extraction using imidazolium based and pyridinium based ILs from the point of ILs design and immobilization of ILs. A series of imidazolium-based ILs [BMIM][BF4], [BMIM][PF6], [HMIM][BF4], [HMIM][PF6] and [BMIM][FeCl4] was designed. The effect of their structures on the extractive performance was investigated. The cations of ILs play an important role in influencing the extractive performance. The imidazolium-based ILs studied in this work have the same anions, and their cations, with the substitution of a longer alkyl group, have better extractive performance. A longer alkyl group makes the cations imidazolium highly polarizable aromatic π-electron densities compared to imidazole. Therefore, the interaction of sulfur compounds and the ILs would be expected to be strong. [BMIM][FeCl4] is a Lewis-acidic IL and stable to air and moisture. Lewis-acid-base interactions enhance the extraction capability of the IL. Moreover, Fe3+ can form π-complexation bonding with aromatic sulfur compounds. These interactions further enhance the extraction power of [BMIM][FeCl4]. The spent [BMIM][FeCl4] IL could be regenerated through reextraction by hexane. A series of pyridinium-based ILs were designed and synthesized. The structure and size of the cations and the sulfur species greatly affect the extractive performance of ILs. For each sulfur compound studied, the extractive performance using pyridinium based ILs followed the order of [C4Py][BF4] < [C6Py][BF4] < [C8Py][BF4] < [C43MPy][BF4] < [C43,5DMPy][BF4] < [C63MPy][BF4] < [C83MPy][BF4] < [C63,5DMPy][BF4] < [C83,5DMPy][BF4]. For a given IL, the sulfur removal selectivity of sulfur compounds followed the order of 4, 6-DMDBT < TS < BT < DBT or TS < 4, 6-DMDBT < BT < DBT due to the difference of aromatic π-electron density of sulfur compounds and the steric hindrance of methyl substitution at the 4 and 6 positions of DBT. The mechanism for the extraction of sulfur compounds with pyridinium based ILs can be explained as the formation of liquid-clathrates and π-π interaction between aromatic structures of sulfur compounds and the pyridinium ring system. The spent IL saturated sulfur compounds could be regenerated by the water dilution process. The desulfurization performance of pyridinium-based ILs is better than that of imidazolium-based ILs. To solve the high viscosity of ILs and the loss of ILs in some applications, a novel method of immobilizing IL of 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] by spraying suspension dispersion was proposed. In order to obtain the better microcapsules, optimal pressure was 0.2 MPa, and the distance between the spraying nozzle and the upper surface of aqueous solution was fixed as 20 cm. In this work the suitable solvent was dichloromethane, shell material was polysulfone and dispersant was gelatin. The polysulfone microcapsules enclosing IL have an average diameter of 70 μm with narrow size distribution and smooth surface, and the encapsulation capacity of microcapsules was 29%. However, compared to free IL, the desulfurization performance of microcapsules will need to be improved due to the IL was encapsulated closely. This approach is also suitable to immobilize other ILs. In order to improve the unsatisfactory desulfurization performance using ILs only as extractant, ILs [BMIM][FeCl4], [BMIM][HSO4] and [C4Py][HSO4] as extractant and catalyst for the coupling the extractive and oxidative desulfurization were explored. For [BMIM][FeCl4], the equilibrium was reached in 10 min and the sulfur removal was 93.2%. For [BMIM][HSO4], under the condition of Vmodel oil /VIL = 2:1, O/S=5, room temperature, the equilibrium was reached in 90 min and the sulfur removal was 99.6%. Moreover, the sulfur removal selectivity of sulfur compounds followed the order of DBT > BT > TS > 4,6-DMDBT. This method is simple, has better sulfur removal, and maybe a high effective and green ultra-desulfurization technology of diesel fuel. |
| 语种 | 中文 |
| 公开日期 | 2013-09-13 |
| 页码 | 142 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1261]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 高红帅. 离子液体萃取及氧化萃取脱硫研究[D]. 过程工程研究所. 中国科学院过程工程研究所. 2010. |
入库方式： OAI收割
来源：过程工程研究所
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