Highly Efficient Removal Of S-/N-Compounds From Fuel Oil With Anion-pillared Hybrid Porous Materials

The efficient removal of sulfur/nitrogen compounds from oil is of great significance for the production of high-quality oil products and environmental protection.The development of deep desulfurization/denitrification technology is extremely challenging.Anion-pillared hybrid porous materials with designable frameworks and abundant hydrogen bonding sites,have exhibited advantages in adsorption,separation and so on.In this work,a series of hybrid porous materials were designed and synthesized as adsorbents to remove the sulfides(benzothiophene,dibenzothiophene)and nitrides(indole,quinoline)from the model oil.In addition,the structure-activity relationship and mechanism of the adsorbents were studied,laying the foundation for the development of new desirable desulfurization and denitrification technology.In this dissertation,a class of anion-pillared microporous materials with different pore sizes and pore shapes were prepared by changing the anions,metal ions and organic ligands,and then the adsorption equilibriums of dibenzothiophene and benzothiophene on these materials were determined.The results showed that the pore shape of the materials had a significant effect on the desulfurization performance.At 298 K,the MOxFy-bpy materials with square channel exhibited extremely high adsorption performance for DBT/BT.For example,the saturated adsorption capacity of SIFSIX-1-Cu for DBT and BT was as high as 101.2 and 131.0 mg S/g MOFs,respectively.TIFSIX-1-Cu showed the highest adsorption capacity of DBT to trace dibenzothiophene(Ce:10 Sppmw,qe:47.47 mg S/g),much higher than the benchmark ever reported.NbOFFIVE-14-Ni material with diamond-shaped pores exhibited a gate-opening effect in liquid phase adsorption process,and its capacity was still significantly lower than that of MOxFy-bpy materials after reaching the opening concentration.The breakthrough experiments confirmed that the MOxFy-bpy materials had great potential to be used as deep desulfurization adsorbents in industry.The adsorption mechanism of dibenzothiophene and benzothiophene in the sub-nano confinement space on the anion-pillared hybrid porous materials was studied by infrared spectroscopy characterization and density functional simulation.It was found that the F atoms of the pillared anions on these hybrid porous materials formed a strong hydrogen bond(H…F)with the H atoms on the guest molecules,and the host-guest interaction could be maximized by pore fine-tuning and pore-shaped regulation.Moreover,the specific pore shape and pore size of the MOxFy-bpy materials could promote the BT molecules to form a "BT" cluster through guest-guest interaction,and then be absorbed into the pore by synergistic host-guest multiple hydrogen bonding.The removal performance and internal mechanism of anion-pillared hybrid porous materials for basic nitride quinoline and neutral nitride indole in model oils were further studied.The results showed that at 298 K,the saturated adsorption capacity of SIFSIX-1-Cu for indole and quinoline reached 578 mg/g and 588.2 mg/g,respectively.At low concentration,SIFSIX-1-Cu also showed excessive high adsorption capacity for trace nitrides(indole:100 ppm,384 mg/g;quinoline:20 ppm,540 mg/g).DFT calculation explained the relationships between structure and property.The result showed that the hybrid porous materials "captured" indole/quinoline molecules mainly by F…H hydrogen bonding,and the square-grid structure facilitated the maximization of the host-guest interaction,resulting in excellent trace nitride removal performance of the material.