Adsorptive Desulfurization Of Liquid Fuels By Using Metal-organic Frameworks Mofs

Fuel combustion is one of the major sources of pollution in the world.It emits toxic sulfur which is harmful to health and the environment.A large ring of aromatic sulfur compounds are found in oil and liquid fuels such as dibenzothiophene(DBT),benzothiophene(BT)and thiophene(T).In order to control the sulfur emission,desulfurization process of the fuel oils is being done.Traditional catalytic hydro-desulfurization(HDS)requires high pressure and high temperature working conditions so it was challenged by several different more efficient and environment friendly desulfurization process.Adsorptive desulfurization is one of them.Different types of adsorbents are being used for adsorptive desulfurization of fuel oils.MOFs are one of the new and highly efficient adsorbents,due to its high porosity and thermal stability and mild working conditions.In this research,different types of(MOFs)were synthesized at different temperatures,different mixed metals and different mixed linkers by using the hydrothermal synthesis and taking MOF-199 as the base MOF material.The desulfurization performance of the prepared adsorbents was evaluated by the adsorption of dibenzothiophene(DBT),Benzothiophene(BT),Thiophene(T)from the model oils at the temperature of 30℃.Firstly,three MOFs were prepared with the different temperatures in order to compare the difference in the crystallinity,size of the pores,shape and framework structure.Temperatures were selected 90℃,100℃ and 120℃ accordingly for the synthesis of the MOF materials.BET surface area,XRD,SEM,TGA/DSC and FT-IR,characterizations were done for the three synthesized samples.Its adsorption isotherms were fitted with Freundlich equation.These MOF materials has good adsorption capacity for DBT,BT and T in the model oil of 1000 ppm S,being 58.83,29.2 and 21.83 mgS.g-1 for MOF prepared at 90℃,58.18,34.93 and 20.29 mgS.g-1 for MOF prepared at 100℃ it can reach,and 58.92,34.64 and 21.23 mgS.g-1 at 120℃ respectively.The results show that the synthesized MOFs at different temperatures didn’t differ much among their physical and chemical properties and thus we can use a lower temperature for synthesize of the selected MOF material.The used MOFs can be regenerated easily by solvent washing and can be recycled at least five times.Secondly,Mixed-metal MOFs were synthesized and MOF-199 was taken as the base MOF for the synthesis.5 different MOFs were synthesized with different concentrations of Copper nitrate and Zinc nitrate.Characterizations were done for all the prepared mixed-metal MOFs and their behavior for adsorption of dibenzothiophenes(DBT)was analyzed at the mild conditions.Mixed-metal MOFs showed decrease in the adsorption capacity due to the deformation of original MOF-199 crystal structure and it decrease with the increase in the concentration of zinc nitrate.Thirdly,Mixed-linker MOFs were synthesized with MOF-199 taken as the base MOF material for the synthesis.Characterizations were done and DBT adsorption capacity over the synthesized mixed-linker MOFs was carried out.Mixed-linker MOFs also deformed with the addition of two linkers(H3BTC and H2BDC)and its adsorption behavior for thiophenic sulfurs also decreased.So in order to get higher desulfurization ability,there is a need to get the better framework structure,size of the pore,shape and crystallinity.