Desulfurization Of Waste Tire Pyrolysis Oil With The Study Of Adsorption Desulfurization Reaction Mechanism

In order to realize the recovery and utilization of waste tire,it was converted into pyrolysis oil,pyrolysis gas and pyrolysis char with through fast pyrolysis technology.The pyrolysis char was used for the desulfurization of pyrolysis oil.In the pyrolysis experiment,waste tire powder was pyrolyzed in the temperature range of 450～650℃.The highest pyrolysis oil yield was obtained at 500℃,reaching 50.47%.The low heating value of waste tire pyrolysis oil reached 38.6 MJ/Kg due to it contained the high content of aromatic compounds.The low heating value of pyrolysis oil is similar to that of industrial liquid fuel,which indicates that waste tires pyrolysis oil has potential as alternative fuels for liquid fuel.In order to improve the quality of tire,many sulfur-containing additives were used in the production process of tire,which resulted in the high sulfur content in the pyrolysis oil.These organic sulfur compounds limit the application of pyrolysis oil.In order to reduce the sulfur content in the pyrolysis oil,pyrolysis char of waste tire was used to produce activated carbon to adsorb the sulfur-compound in this study.KOH was used as activating agent in the production of waste tire activated carbon.Pyrolysis char was activated at 750℃ for 1 h.The specific surface area of activated carbon reached 680 m2/g.In order to optimize the operation conditions of desulfurization process,the influence of desulfurization temperature,desulfurization time and adsorbent usage on the desulfurization rate were investigated.The optimum desulfurization effect of activated carbon was obtained when the desulfurization temperature fixed at 20℃ for 12 h.In order to improve the desulfurization ability,the waste tire activated carbon was modified by loading metal ions and nitric acid pretreatment.In this study,Ag+showed the better effect on improving the desulfuization rate of waste tire activated carbon,compared with the other metal ions.The adsorption capacity of the raw activated carbon was unsatisfactory,only 15.33%of organic sulfur was removed.After modification,the desulfurization ability of activated carbon was improved significantly,and the desulfurization rate reached highest value of 71.4%.In 1 mL pyrolysis oil,the optimum adsorbent(Ag-Zn/AC)usage was considered to be 0.1 g.Furthermore,the reaction mechanism between the modified activated carbon and organic sulfur during the desulfurization process was investigated by using Ag+ and aibenzothiophene as model compounds.The reaction process of Ag+ with dibenzothiophene was monitored by in situ infrared.The reaction products were analyzed by1H NMR,ICP-OES and elemental analysis.The results show that the coordination reaction between Ag+and dibenzothiophene occurs in solution with coordination number of 1.The in situ infrared spectra show that there are two reaction sites on the dibenzothiophene molecule,namely S atom and benzene ring.Therefore,it can be concluded that there are two kinds of complexes may be produced during the process,which were Ag(Ds)NO3 and Ag(DC6H6)NO3.