| The generated SOx that caused by combustion of organic sulfur compounds in the vehicle fuel,which may influence on air pollution and forming acid rain,and then affect human health and the ecological environment directly.China has successively implemented the gasoline and diesel sulfur content standard of state III-V to decrease from 150?g/g to 10?g/g,this means that it is of significance to strengthen the production of clean fuel products.Hydrogenation desulfurization(HDS)process is regared as the popular desulfurization technology for oil refining industry,which can remove a large number of organic sulfur compounds effectively,but it is difficult to remove thiophene sulfur compounds from condensed rings.At the same time,HDS has many disadvantages such as harsh reaction conditions,large consumption of hydrogen,high cost and other shortcomings.This compels people to look for economic and efficient non-HDS technologies(xidation desulfurization,extraction desulfurization,alkylation and adsorption desulfurization and so on).Adsorption desulfurization has many advantages,such as mild operation conditions,low investment cost,good desulfurization selectivity and renewability of adsorbent specially.As far as adsorbent is concerned,activated carbon is widely used in the field of desulfurization with its unique advantages.While,activated carbon preparation process has many problems,such as a complex step,high energy consumption and large amount of wastewater discharge.In addition,traditional liquid-solid adsorption desulfurization also has many disadvantages,such as large mass transfer resistance,long balance time and large oil consumption.Therefore,this paper focuses on the preparation of activated carbon and its application in liquid/gas-solid adsorption desulfurization process.Commercial activated carbon is used as the carrier material,firstly H2SO4-AC,HNO3-AC and HNO3-H2SO4-AC was obtained through oxidation modified,then regard HNO3-AC as the precursor,a series of Ni/AC,Cu/AC,Ca/AC and Fe/AC was gained by metal load modified,the desulfurization experiment of DBT model fuel was discussed among those adsorbents under the liquid-solid adsorption condition(0.2g adsorbent/10mLDBT,adsorption temperature room temperature,adsorption time 12h).The results showed that the order of desulfurization performance for adsorbents:Ni/AC>Cu/AC>Ca/AC>HNO3-AC>HNO3-H2SO4-AC>H2SO4-AC>AC>Fe/AC,the Boehm method indicated that HNO3 could enhance the C=O functional group on its surface effectively and increased the desulfurization performance through the electron donor-acceptor force,different oxidizing agent had different oxidizing effects on the activated carbon adsorption desulfurization.The result of XRD and SEM showed that the corresponding metal oxides could be dispersed on the surface of the adsorbent to form new active adsorption sites after metal load modified,the different desulfurization results indicate that different metals had different ?-complex bonds force and caused different desulfurization performance.At the same time,the traditional liquid-solid adsorption desulfurization experiments showed that the aromatics had negative effect on the adsorption desulfurization performance for DBT model fuel.Based on this issue existing in traditional activated carbon preparation process and liquid-solid adsorption desulfurization process,the activated carbon based adsorbent NiO/AC have been obtained by one-step method(400? arbonization,activation and modification)at low temperature for the first time,and investaged the desulfurization performance for DBT model fuel and real oil over NiO/AC under liquid-solid and gas-solid adsorption desfurization conditions.Boehm method showed that there were many oxygen functional groups on the surface of the adsorbent,such as carboxyl,lactone,and phenolic hydroxyl groups,XRD analysis showed that NiO could be dispersed on the surface of adsorbent to form new active adsorption sites reasonably.Experiments showed that the quality of nitric acid in the impregnation solution fraction was 30%,the loading amount of NiO was 5%,the impregnation time was 24h,the calcination time was 3h,which was the optimum liquid-solid adsorption preparation conditions for activated carbon based adsorbent.Under the adsorption temperature was 40? and adsorption time was 5h,the liquid-solid adsorption desulfurization performance was 28.36%,single adsorption capacity was 1.99mgS/g,the saturated adsorption capacity could reach 2.34mgS/g after 4 times adsorption desulfurization for DBT model fuel.Under the adsorption temperature was 250? and space velocity was 6.3h-1,the gas-solid he saturated adsorption capacity was 2.37mgS/g.The selective desulfurization experiments of adsorbent on model fuel and real oil showed that the model fuel was better than real oil in terms of adsorption desulfurization performance.The gas-solid adsorption desulfurization process reduces the competitive adsorption of aromatic compounds,and eliminates the influence of aromatic hydrocarbons on thiophene sulfur compounds adsorption desulfurization.The regeneration experiment showed that the regeneration efficiency of adsorbent could reach 96.48%after the regenerated toluene solvent,and regenerated performance could be up to 90%after 5 times cycle utilization.After the high temperature gas-solid adsorption experiment,the specific surface area,total pore volume and micropore volume increased to 106.89m2/g,0.098cm3/g and 0.078cm3/g compared with before,which indicated that the adsorbent occurs reactivation in the process of gas-solid adsorption desulfurization process simultaneously. |
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