银基吸附剂脱除噻吩类含硫化合物机理的研究进展

Review of Desulfurization Mechanisms for Sulfur-Containing Thiophenic Compounds over Silver-Based Sorbents

噻吩类含硫化合物因其稳定的共轭结构是油品中较难脱除的含硫化合物,银基吸附剂对其有较好的脱除性能。对银基吸附剂上活性组分银与噻吩间3种类型的作用机理进行了综述,3种类型的作用方式为π络合,S-Ag键及软酸Ag(Ⅰ)和软碱噻吩的相互作用。脱硫过程中,作用方式的类型及其强弱不仅受到噻吩类含硫化合物分子尺寸、共轭程度及硫原子电负性的影响,还与银的存在形态及其与载体间作用有关。π络合作用对芳烃/烯烃和噻吩硫的吸附存在竞争作用,适合于不含芳烃和烯烃体系中硫化物的脱除;S-Ag键主要是金属的空轨道与硫原子的孤对电子之间的作用,相对而言更适合于芳烃存在体系中噻吩硫的脱除。针对不同的脱硫体系,需要借助最适合的作用机理对吸附剂上银的存在形态和分布进行精准的定向调控。

Thiophenic sulfurs are difficult to be removed from liquid fuels because of their stable conjugated structures.Ag-based sorbents had excellent desulfurization performance.The interaction mechanisms between silver active component on silver-based sorbents and thiophene were reviewed.The three types of interactions models wereπcomplexation,S-Ag bond,and the interaction between soft acid Ag(I)and soft base thiophene.In the process of desulfurization,the types of action modes and their strength not only affected by the molecular size,conjugation degree,and electronegativity of sulfur atoms of thiophenic compounds,but also related to the silver existence form and its interaction with the carrier.Forπcomplexation,the competitive adsorption effects of aromatics/olefins on thiophenic sulfur made it more suitable for the desulfurization in system without aromatics and olefins.For the S-Ag bond,which was the interaction between the empty orbit of the metal and the lone pair electrons of the sulfur atom,was relatively more suitable for the desulfurization in system with aromatics.For different desulfurization systems,the most suitable mechanism of action was required to precisely regulate the presence and distribution of silver on the sorbent.