金属有机骨架材料MIL-101吸附脱硫性能的研究

Adsorptive Performance of Sulfur Compounds on Metal Organic Framework Material MIL-101

采用水热合成法制备了金属有机骨架材料MIL-101,基于固定床动态吸附实验,研究了室温下MIL-101对模型气体中的甲硫醚、乙硫醇及硫化氢的吸附性能和脱除机理。对硫化后的样品进行XRD和TG-MS分析,并用密度泛函理论进行MIL-101吸附硫化物的计算。研究结果表明,MIL-101对甲硫醚有最佳的吸附容量(m(S)/m(MOFs)=24.2mg/g),其次为乙硫醇(m(S)/m(MOFs)=14.9mg/g),硫化氢最差(m(S)/m(MOFs)=5.8mg/g)。3种硫化物在MOFs上吸附后并未破坏骨架主体结构;吸附后甲硫醚主要以分子形态存在于MOFs骨架中,硫化氢则与骨架发生化学作用。理论计算表明,MIL-101对硫化物的吸附主要发生在不饱和金属中心上,且硫化物的平均吸附能随着被吸附分子数量的增加而减弱。不饱和金属位对硫化物吸附的强弱顺序为甲硫醚,乙硫醇,硫化氢,这与实验得到的3种硫化物的硫容顺序相一致。

MIL-101 was synthesized by hydrothermal method.The fixed bed was employed to carry out the dynamic adsorption experiments for dimethyl sulfide,ethyl mercaptan and hydrogen sulfide at ambient temperature.The sulfuretted samples were characterized by XRD and TG-MS techniques.The density functional theory was used to calculate the adsorption energies of three sulfides over the MIL-101.It was found that the adsorption capacity is m（S）/m（MOFs）=24.2mg/g,m（S）/m（MOFs）=14.9mg/g and m（S）/m（MOFs）=5.8mg/g for dimethyl sulfide,ethyl mercaptan and hydrogen sulfide,respectively.The framework of MIL-101 was not damaged after breakthrough experiments.Results show that dimethyl sulfide was adsorbed on the MIL-101 in its molecular form,whereas hydrogen sulfide could react with MIL-101.The theoretical calculation demonstrated that coordinatively unsaturated metal site（CUS）is the main position to adsorb sulfide,and the average adsorption energies over CUS of MIL-101 weaken with the increased number of sulfide.The adsorption sequence over CUS is CH_3SCH_3,CH_3CH_2 SH,H_2S,which is coincidence with the order of sulfur capacity obtained from experiment results.