| The refinery's straight-run gasoline,light diesel oil,fuel oil,FCC gasoline and FCC diesel,are mainly used to reconcile the automotive gasoline and diesel.The generated SOx which caused by burning sulfur compounds have further aggravated air pollution,so it is of great significance for low-sulfur gasoline and diesel on the deep desulfurization of distillate oil.The traditional hydrodesulfurization(HDS)can effectively remove most of the sulfur compounds in distillate oil,but it needs high temperature and high pressure operation,and there are many problems such as high hydrogen consumption and the little removal of thiophene and other macromolecular sulfides.The adsorption,oxidation,extraction,alkylation and other non-hydrogenation desulfurization method will ease the operating conditions and favor the removal of thiophene and other large molecular sulfides.The selective adsorption method can reduce the sulfur content,while easy to liquid-solid separation,and cyclic utilization.The lignocellulose biomass is chosen as carbon precursor to prepare biochar with large specific surface area,rich pores,and oxygen-containing functional groups for the pollutants adsorption due to its perfect properties on abound resources,cheapness,green cleaning and high carbon content.In this paper,the properties of various kinds of biochars were evaluated,the lignin-carbon with excellent performance was selected,and the study on the adsorptive desulfurization of lignin-carbon(LC)from simulated sulfur oil and distillate oil was discussed.In this study,the 12 kinds of waste biomass such as sawdust,corn stalks,pine leaves,Washingtonia filifera,Eupatorium adenophorum,packing paper,sugar cane,coconut shell,oil cake,rape rod,cotton stalk and lignin were as raw materials for prepared a series of biochars in high temperature under the chemical activation of KOH?ZnCl2 and H3PO4 to adsorb S-containing compounds of DBT simulated oil and real diesel.The results showed that the activation temperature of KOH was the highest with the best adsorption effect,and DBT adsorption capacity of biochars were more that 70%but the lowest char yield;we firstly found that the higher lignin content in biomass,the higher char yield and the better desulfurization effect;the effect of pure lignin was better than above-mentioned biomass in sulfur adsorption,and less ash,largest proportion of carbon.And then the two components of cellulose and lignin were separated.According to structure and thermogravimetric analysis,it concluded that the decomposition temperature of lignin was higher than that of cellulose,and stronger thermal stability.Therefore,the following tests were conducted with lignin as biochar source.The study was carried out innovative improvement in activator.Potassium hydrogen phthalate was first-time used as chemical activator to modified lignin into lignin-based biochar,which was applied for adsorption desulfurization.Fourier transform infrared spectroscopy(FT-IR)and Boehm titration were used to qualitatively and quantitatively analyze the changes of oxygen polar groups on the carbon surface,respectively.Scanning electron microscopy(SEM)/transmission electron microscopy(TEM)and pore structure determination(BET-NLDFT)were employed to characterize the pore structure properties of biochar from two aspects of macroscopic and microscopic views.The whole process of lignin pyrolysis was evaluated by thermogravimetric analysis(TG/DTG).The results showed that when the addition amount of KHP to lignin was 2 times(ie.LC-2),the lignin-based biochar could be activated at 800OC for lh,the most acidic and carbonyl groups were 1.07mmol/g and 0.s3mmol/g on the carbon surface,respectively.The largest surface area was 912m2/g and the total pore volume was 0.365cm3/g,among which the micropore proportion(pore size<2nm)was 60.3%,followed by LC-3 and LC-1.The whole data indicated that LC-2 should be the best adsorbent,the next adsorption experiments could be verified the fact.A series of contrast and optimizing experiments of DBT adsorption were carried out and focused on the preparation conditions of impregnation ratio,activation temperature,impregnation time,and ADS conditions of adsorption time,carbon/oil ratio,initial sulfur content.And these LCs applied to the real distillate oil,and compared with the selectivity and adaptability in the complex environment.The isothermal adsorption curves were charted based on the Langmuir and Freundlich models and the primary form of adsorption was analyzed.Under the optimum adsorption condition(m(KHP):m(lignin)=2:1,impregnation time 12h,activation temperature 800?,adsorption time 4h,carbon/oil ratio=0.1g/10mL,initial DBT content 500pg S/g),the maximum desulfurization rate reached 98.8%and the highest adsorption capacity achieved 41.7mg·S/g.The removal of distillate oil from complex sulfur environment was less than that of simulated oil,but the removal efficiency of light diesel oil riched in DBT was better than that of straight-run gasoline and FCC gasoline,and the selectivity for DBT adsorption is preferable than that of T and BT.The adsorption process was better fitted to the Langmuir isothern equation,which indicated that the adsorption process was more likely to be adsorbed on the monolayer,the larger specific surface area and better polar groups could provide more adsorption sites and stronger adsorbing force for better adsorption ability. |
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