Preparation Of ?-complexed Adsorption MOFs And Study On Their Desulfurization Performance

The sulfur compound in fuels causes a great deal of pollutions to the environment,which seriously endangers human health.Therefore,the research and development of desulfurization technology for fuel is becoming very important.The removal of sulfur compounds from fuels was conducted industrially via catalytic hydrodesulfurization(HDS),but the technology is harsh in operation,which requires high temperature,pressure,hydrogen consumption and industrial cost In addition,the octane number of fuels is obviously decreased in the HDS process.As one kind of efficient and environmentally friendly separation method,adsorption is thought that it is an alternative technique as it can avoid the use of H2 in the process and can be performed at mild conditions.The ?-complexation bonds are weaker than the chemical bond,but they are stronger than the van der Waals interactions.So,fortunately,the regeneration performance of adsorbents via ?-complexation is superior to those of chemical adsorbents,and ?-complexation adsorbents have higher adsorption capacity in desulfurization than physical adsorbents.It has become the most advantageous desulfurization technologyAt present,activated carbon,zeolites,metal oxides and other porous materials are mainly used for adsorption desulfurization.Metal Organic Framework Materials(MOFs)are a new type of organic-inorganic porous materials.Compared with traditional adsorbents,MOFs have the advantages of large specific surface area and porosity,adjustable pore size and many kinds of advantages.MOFs have broad prospects in the field of liquid and gas adsorption and separation,and also have great potential in the field of adsorption and desulfurization.In this paper,Ag(I)and Cu(I)supported metal organic skeleton materials were prepared to study the adsorption and desulfurization properties of thiopheneCu-BTC-DMA was synthesized by hydrothermal method.Ag@Cu-BTC-DMA was successfully synthesized by ion exchange method,and the crystal structure of the adsorbent remained intact after ion exchange.The order of the adsorption and desulfurization performance of the four adsorbents for thiophene is:Ag@Cu-BTC-DMA(0.02M)>Ag@Cu-BTC-DMA(0.01M)>Ag@Cu-BTC-DMA(0.03M)>Cu-BTC-DMA.This indicates that the adsorbent has good adsorption selectivity to thiophene after the introduction of Ag+.Competitive adsorption experiments show that the adsorption capacity of thiophene by adding 5w%toluene,Ag@Cu-BTC-DMA(0.01 M),Ag@Cu-BTC-DMA(0.02 M)and Ag@Cu-BTC-DMA(0.03 M)decreases by 18.4%,15.2%and 26.7%respectively,which indicates that the selectivity of the adsorbent has been improved after the introduction of Ag+.After four cycles of regeneration,Ag@Cu-BTC-DMA(0.02 M)still has 86%adsorption capacity for thiophene,which indicates that the adsorbent has good recyclabilityIn order to further improve the stability and selectivity of adsorbents,Cs+was introduced into Ag@Cu-BTC-DMA(0.02 M)skeleton by re-ion exchange,and AgCs@Cu-BTC-DMA was prepared.Static adsorption experiments showed that compared with Ag@Cu-BTC-DMA,the adsorption capacity of thiophene on all samples increased after Cs+ion exchange.This was mainly due to the ?-complexation between Ag+,Cs+and thiophene,and the coordination between bimetals,which improved the adsorption and desulfurization performance of thiophene on the adsorbent The order of thiophene adsorption performance of these five adsorbents is AgCs@Cu-BTC-DMA(1:1)>AgCs@Cu-BTC-DMA(2:1)>AgCs@Cu-BTC-DMA(2:3)>Ag@Cu-BTC-DMA(0.02 M)>Cu-BTC-DMA.For the model oil with 600 ppm concentration in the presence of 5 w%toluene,the adsorption of thiophene by AgCs@Cu-BTC-DMA(2:1),AgCs@Cu-BTC-DMA(1:1),Ag@Cu-BTC-DMA(2:3)decreased by 14.5%,10.6%and 20.8%respectively.This shows that the selectivity of adsorbent improved after adding Cs+.After four cycles of regeneration,AgCs@Cu-BTC-DMA(1:1)still remained 90%adsorption capacity for thiophene,which was mainly due to the cooperative interaction between bimetals,which improved the stability of the adsorbent.Because the ?-complexation between copper and thiophene is stronger than that between Ag+and thiophene,Cu2+ @ Cu-BTC-DMA is synthesized by ion exchange,and then Cu+@Cu-BTC-DMA is obtained by ethanol vapor reduction.The adsorption and desulfurization properties of thiophene by adsorbents at different reduction temperatures were investigated.Static adsorption experiments show that the adsorption and desulfurization performance of thiophene on the modified adsorbent is improved and higher than that of Ag@Cu-BTC-DMA,which is mainly attributed to the ?-complexation between copper and thiophene.The order of thiophene adsorption performance of these four adsorbents is:Cu+@Cu-BTC-DMA(180?)>Cu+@Cu-BTC-DMA(200?)>Cu+@Cu-BTC-DMA(160?)>Cu-BTC-DMA.After adding 5w%toluene,the adsorption of thiophene by Cu+@Cu-BTC-DMA(160?),Cu+@Cu-BTC-DMA(180?),Cu+@Cu-BTC-DMA(200?)decreased by 16.8%,12.5%and 22.15%respectively.This shows that the adsorbent has good selectivity for thiophene.After four cycles of regeneration,the amount of thiophene still adsorbed by Cu+@Cu-BTC-DMA(180?)decreased by only 12%,indicating that the adsorbent has good cyclic regeneration.