Preparation And Characterization Of Adsorbents Based On MOF-74(Ni) And The Study Of The Adsorption Desulfurization Performance

It can produce the sulfur oxides contaminant when the fuel oil,which is include sulfur-containing compounds(S-compounds),is burned.The sulfur oxides not only affect human health but also destroy the entire ecosystem,so all governments have developed strict sulfur content standard in the fuel oil.Amount all desulphurization technologies,adsorption desulfurization(ADS)is considered as one of the most promising and high-speed developed process and has attracted much attention of scientific researchers and enterprises due to the numerous remarkable advantages such as mild operation conditions,low energy consumption,no need of hydrogen or oxygen,pollution-free and environment friendly nature,excellent removal efficiency for refractory S-compounds such as benzothiophene(BT),dibenzothiophene(DBT),4,6-dimethyldibenzothiophene(4,6-DMDBT)and their derivatives.Meantime,ADS for ultra-low sulfur fuel oil can overcome the shortcomings of reduction in octane number and decrease in quality of gasoline and diesel fuel oil.In this paper,we select MOF-74(Ni)loaded on the ?-Al2O3 beads to obtain MOF-74(Ni)@?-Al2O3 composite as adsorbent for adsorptive desulfurization.In addition,AgNPs@MOF-74(Ni)composite is prepared by encapsulating silver nanoparticles(AgNPs)in MOF-74(Ni),and the AgNPs@MOF-74(Ni)composite is adsorbent to improve the selectivity for S-compounds.The main work is as follows:(1)In this part,the microporous MOF-74(Ni)was impregnated effectively on millimeter-sized mesoporous ?-Al2O3 beads leading to successful formation of a hierachical multiporous(micropore and mesopore)composite MOF-74(Ni)@?-Al2O3 via hydrothermal method.The composite not only showed excellent adsorptive desulfurization in the order of DBT?BT>4,6-DMDBT>3-MT with the adsorptive desulfurization capacity of 67.46 mg S g-1 MOF for 1000 ppmws DBT in a model oil,but also applied nicely for ultra-deep adsorptive desulfurization wherein the DBT and BT content of 35 ppmws in a model oil was decreased down to 2.30 and 4.28 ppmws,respectively,with high selectivity in presence of aromatics(Selective factor of 5.98).Notably,the excellent performance of adsorptive desulfurization in FCC gasoline(44.2 mg S·g-1 MOF for 689.2 ppmws)was also realizeded by using the as-prepared composite.In addition,the high mechanical and chemical stability of composite enabled the good recyclability and high fluidity.All the above excellency endowed the as-prepared composite the great potential in practical adsorptive desulfurization process at industrial level in the future.(2)In this part,AgNPs@MOF-74(Ni)composite was synthesized by encapsulating silver nanoparticles in MOF-74(Ni)via hydrothermal method.The successful loading of AgNPs@MOF-74(Ni)composite was characterized by IR,XRD,SEM,TEM,HRTEM,XPS and elemental analysis.The composite as adsorbent removed the aromatic sulfur compounds such as 3-MT,BT and DBT,and showed the excellent adsorptive desulfurization performance than MOF-74(Ni).The adsorptive desulfurization capacity of 1.23%AgNPs@MOF-74(Ni)was 65.04 mg S·g-1 A for 1000 ppmws DBT,which was increased by 11.75%than that of MOF-74(Ni)(58.20 mg mg S·g-1 A).In addition,the composite also revealed excellent ultra-deep and selective adsorptive desulfurization performance,the removal rate for 35 ppmws DBT of composite was increased from 85.05%to 94.26%compared with MOF-74(Ni),and the selectivity factor of adsorping DBT to naphthalene over 1.23%AgNPs@MOF-74(Ni)was 7.13.Besides,the composite still have outstanding reusability.AgNPs were highly dispersed in MOF-74(Ni),and did not clog the pores of MOFs,so the structure of MOFs was not destroyed.And 1.23%AgNPs@MOF-74(Ni)was reused five times and keep the adsorptive desulfurization capacity for DBT as high as 58.34 mg S·g-1 A.