焦化苯中噻吩深度脱除用吸附剂的制备及其构效关系的研究

Coking benzene, which is one of the main by-products from coal coking process,accounts for about 40-50% in the total amount of benzene in China. But the share of coking benzene in pure benzene is only below 20% because the impurities contentes in it are higher than in petroleum benzene and they are hardly removed. The existing methods are already not able to meet the limitation of sulfur content in benzene as raw meterial with the increase of benzene quantity demanded and the enhancement of down-stream product needed purity.The thiophene containing in coking benzene, which presents very slmilar physical and chemical properities, are the main factor influencing the quality of benzene. The deep removal of thiophene from coking benzene by effective method without second pollution is the purpose of this research topic. The research results will present the great theoretical significance and the remarkable social and economic benefits. The main contents in this research are shown as follow. To select the precursor materials with excellent performances and then to prepare sorbents and modify them under different conditions; evaluate the selective adsorption capacity of deep removing thiophene in benzene over improvement sorbent; characterize the physical and chemical properties (e.g. the surface acidity or basicity, the porous structure, the load and distribution of metal components and so on) of sorbents before and after desulfurization reaction; relate the experimental results of preparation, modification, evaluation and characterization and discuss the mechanism of selective adsorption thiophene from benzene.The polymerization of thiophene and synthesization of thiophene/sorbent composite materials are also preliminarily explored. A kind of sorbent with good performances, which owns the capacities to deeply remove thiophene and be recycled, will be obtained based on the analysis of above mechnism and the structure-effective relationship of sorbent.

焦化苯作为煤焦化的主要副产物之一，约占我国苯总产量的40-50%，但因其杂质含量高难脱除而在纯苯中所占比例小于20%。随着对苯需求量的增长和下游产品对原料苯纯度要求的提高，现有焦化苯精制方法越来越难以满足需求。粗苯中含有的与其物化性质非常相近的噻吩是影响焦化苯品质的主要因素，基于吸附机理对其进行深度脱除获得符合原料用纯苯ppb级噻吩含量的要求是课题研究的目标，研究结果将具有重要的理论意义和显著的经济、社会效益。研究内容主要包括：吸附剂前驱体材料的选择、不同工艺条件下的制备和改性；吸附剂选择性深度脱除噻吩的活性评价；噻吩脱除前后吸附剂表面酸碱性、孔结构以及金属组分的负载特性和分布等物化性能变化的表征；制备、改性、评价条件与表征结果的关联，以及噻吩吸附脱除机理的探讨。同时进行吸附的噻吩聚合及聚噻吩/吸附剂复合材料合成的可行性探讨，以期获得能深度脱除焦化苯中噻吩并可回收利用的优良的吸附剂。

焦化苯资源丰富，但因含有的杂质使其应用受到了制约。随着国内市场对苯需求量的增长、下游产品对原料苯纯度要求的提高，焦化苯深度脱硫提质利用已成为必然的趋势。粗苯中含有的与其物化性质相近的噻吩是影响焦化苯品质的主要因素，在探明吸附脱硫机理的基础上对其进行深度脱除获得符合原料用纯苯ppb级噻吩含量的要求是课题研究的目标。鉴于噻吩的经济价值及吸附噻吩后分子筛再利用能力，同时进行了聚噻吩/分子筛复合材料合成研究的初探。项目在国家基金委和太原理工大学的资助和支持下，完成了吸附剂前驱体材料的优化选择、不同工艺条件的改性、选择性深度脱除噻吩的活性评价和噻吩吸附机理的探讨；噻吩脱除前后吸附剂孔结构及金属组分的负载特性和分布等物化性能的表征；噻吩烯烃烷基化转化机理探讨以及分子筛吸附剂与噻吩单体进行聚噻吩/分子筛聚合物合成的初探等研究工作。发表标注基金的学术论文3篇（SCI和EI收录5篇次）；申报国家发明专利1项，培养和在培养研究生4名。. 研究成果主要表现在：(1) γ-Al2O3等体积浸渍负载金属元素制得的改性吸附剂中，Ag含量为15%的Ag/γ-Al2O3吸附剂对噻吩的脱除性能最佳，噻吩的吸附主要以银与噻吩环间的π络合进行；吸附剂制备过程中，等体积浸渍的同时进行超声辅助，可缩短制备时间，丰富吸附剂的孔隙结构，细化活性组分颗粒并使其分布均匀。(2) NaY分子筛金属离子交换改性制得的吸附剂中，铈离子改性的CeY吸附剂脱硫效果最佳，在室温、常压、液剂比为4mL/g时，可将噻吩浓度为500 mg/L的噻吩-苯溶液中的噻吩完全脱除。(3) 采用常压和高压气相负载法制备的负载型AlCl3催化剂中，加压气相负载法制得的催化剂对噻吩与烯烃的烷基化反应活性更高，硅胶比γ-Al2O3更适合作为催化剂载体，负载过程主要是通过AlCl3与硅胶表面羟基的作用，以“Si-O-Al”的形式结合到硅胶表面上。(4) 以脱硫性能较好的CeY吸附剂吸附噻吩前后的样品和噻吩为原料，用化学氧化聚合法进行了聚噻吩/分子筛复合材料合成的初探，证实了氯仿为溶剂，无水FeCl3为氧化剂，在0℃条件下化学氧化法可制得噻吩环之间主要以α-α方式连接的复合材料，该材料基本保持了分子筛的晶体结构，对紫外-可见光有较好的吸收，具有作为光电材料的应用前景。