Adsorption Performance Of Thiophene With Multi-Metallic-Carboxyl-Ligands MOFs Materials

Metal-organic framework materials(MOFs)have attracted much attention in the field of deep desulfurization due to their advantages of structural diversity,unsaturated adsorption sites and high specific surface area,etc.However,the selectivity and adsorption capacity are restricted to MOFs because of unsaturated adsorption sites of single metal.In addition,the applications of MOFs are largely limited by the poor hydrothermal stability.Aiming to overcome these shortcomings,multi-metallic-carboxyl-ligands MOFs materials are designed and synthesized,whose adsorption performances of thiophene are also studied in this paper.There are following three parts:1.Three-metal MOFs material,Zn/Ni/Cu-BTC consisting of three different central metals(Cu2+,Zn2+and Ni2+)and one organic ligand(1,3,5-benzene tricarboxylic acid,H3BTC)was designed and synthesized by hydrothermal synthesis technique.Characterization of the MOFs material was confirmed by N2 adsorption,SEM,XRD,ICP and single crystal structure analysis.The adsorption performance of thiophene was investigated by batch adsorption experiments.The results showed that as-synthesized MOFs material has a octahedral structure and a good thermal stability at 300 ?.The BET specific surface area of the MOFs is in the range of 1047?1386 m2/g.The results of batch tests shown that the saturation adsorption capacity of thiophene onto Zn/Ni/Cu-BTC in aliphatic oil,aromatic oil and mixed oil are 330,169 and 304 mg/g,which were higher than those previously reported in the literature.Adsorption process follows the pseudo-second-order model and Langmuir models.2.BTC as ligand,zinc,nickel and copper as metal source and phosphotungstic acid(PTA)as modifier,PTA@Zn/Ni/Cu-BTC materials were prepared by one pot hydrothermal synthesis method.The structure and thermal stability of the composites were characterized by N2 adsorption,SEM,XRD,TGA,and FT-IR,etc.The adsorption performance of thiophene were investigated before and after modified with PTA.The results shown that the PTA@MOFs were octahedral structures shape.The BET specific surface area decreased from 1229 m2/g to 294 m2/g(a decrease of 76%)due to doped wth PTA.The material structure still maintains stable at 300 ?.The adsorption capacity of thiophene sulfur onto Zn/Ni/Cu-BTC increased from 330 mg/g to 391 mg/g(an increase of 18.5%)after PTA modification.The adsorption process of thiophene sulfur onto PTA@Zn/Ni/Cu-BTC fitted with Langmuir model and pseudo-second-order model.3.2-bromo-1,3,5-trimethylbenzene ligand was prepared by oxidation of potassium 2-bromo-1,3,5-trimethylbenzene with potassium permanganate.Copper as the metal source,a brine-containing hydrophobic material,Br-Cu-BTC was prepared by hydrothermal synthesis method.The Br-Cu-BTC material was characterized by N2 adsorption,XRD and FT-IR,etc.Adsorption performances of thiophene onto Br-Cu-BTC were studied in aqueous fuel.As a result,the Br-Cu-BTC is a normal octahedral crystal structure with microporous and mesoporous coexistence.The BET specific surface area of Br-Cu-BTC is 603 m2/g and its pore volume and the average pore size are 0.29 mL/g and 3.42 nm.The adsorption capacity of thiophene sulfur increased from 208 mg/g to 247 mg/g(an increase of 19%)because of doping with-Br hydrophobic group,which improved the hydrophobic properties of the material and avoided the competitive adsorption between water and thiophene molecules.