Study Of The Synthesis And Adsorption And Nitrogen Removal Properties Of Ti-based Porous Material

Nowadays,due to the wide use of liquid fuel oil,the combustion of the nitrogen oxide,emissions into the atmosphere can cause damage to the environment.Therefore,it is very necessary to remove the nitrogen-containing organic matter in the fuel oil.Adsorption and nitrogen removal had the advantages of simple operation and low energy consumption,and it is an effective method to remove nitrogen-containing organic matter in fuel oil.The key to adsorption and nitrogen removal is to prepare an adsorbent with high nitrogen capacity and high selectivity.MOFs are good adsorbed materials with the advantages of topology,high porosity and structural structure.In this paper,Ti-MOF with different amino content and morphology investigated the influence of crystal surface and structure on its adsorption properties.Then the Ti-MOF material was handled at different temperatures,further increasing the oxygen vacancy of the Ti-MOF,the influence of the hole diameter structure on the adsorption properties was investigated.Finally,the molecular dynamics simulation of Ti-MOF adsorption was studied from the molecular level.A promising adsorbent for purifying liquid fuel oil will be developed.It specifically includes three parts:（1）The MOFs’ligands can have a great impact on their adsorption properties,and the ligands of Ti-MOF are the terephthalic acid and 2-amino terephthalic acid.TBOT as the metal titanium source,Ti-MOFs with different ligand ratios were synthesized by hydrothermal method.The adsorption experiments showed that The ammonia（-NH₂）group had a significant impact on the adsorption performance,and Ti-MOF prepared by2-ammonia terephthalic acid was the best.At the same time,it is found that the Ti-MOF crystal is also selective in facing the adsorption properties,and（111）the crystal surface is beneficial for the adsorption.（2）NH₂-MIL-125（Ti）was calcined and then subjected to pore increasing treatment.XRD and FT-IR analysis showed that Ti-MOF structure will collapse when it exceeds300℃,and the structure of Ti-MOF can be completely preserved after treatment at250℃.SEM also proves the above results.N₂physical adsorption desorption,XPS and ESR results showed that Ti-MOF treated at 250℃had more oxygen vacancies,and the adsorption performance showed that NH₂-MIL-125@250℃had the best denitrification performance,and the maximum adsorption capacity of indole and quinoline can reach262 mg/g and 251 mg/g respectively.Through the calculation of adsorption kinetics and thermodynamics,it is found that the pseudo second-order kinetics and Langmuir adsorption isotherm model are consistent with the two models in this experiment.The adsorption process of indole and quinoline is exothermic.The adsorption mechanism was discussed by FT-IR,XPS and DFT calculation.It was found that H bond andπ-πinteraction played a major role in the adsorption process of indole,andπ-πand Ov interaction were the main adsorption structures in the adsorption process of quinoline.The repeated experiments showed that the adsorbent after heat treatment has better regenerative properties.（3）Molecular simulation technology was used for the study nitrogen-containing organic matter on the surface of Ti-MOF and cavity adsorption and diffusion behavior.At the same temperature,the adsorption order of indole and quinoline in the NH₂-MIL-125 cell model was:IND>QUI.The order of the adsorption heat and diffusion coefficient was:QUI>IND.Both IND and QUI had only one adsorption site in the NH₂-MIL-125 cell model.The increase of temperature greatly improved the mass transfer process,the adsorption amount and adsorption heat of the two molecules were reduced in the model.