Study On Adsorption Desulfurization Of Methyl Tert-butyl Ether

Methyl tert-butyl ether?MTBE?is an important gasoline additive in China.It is mainly prepared by etherification of methanol and isobutylene.However,the mass fraction of sulfide in MTBE is generally high,which seriously affects the gasoline reconciliation and product upgrades.Methods to reduce the sulfide content in MTBE mainly are:MTBE distillation desulfurization and raw material refining,but these methods still have some problems.The removal of sulfide from MTBE by adsorption method has the advantages of mild operating conditions and low energy consumption,but the requirements for selectivity of adsorbents is high.In this paper,the preparation process and the modification of the active component of adsorbent are optimized,the desulfurization performance of the adsorbent is also investigated.The adsorbent carrier is prepared by kneading based on a commercial ZSM-5zeolite as raw materials.The adsorbent is characterized by XRD,BET and NH₃-TPD.With reagent grade of methyl tert butyl ether as the raw material,the preparation conditions of adsorbent carrier are investigated by static adsorption desulfurization at normal temperature and atmospheric pressure.The experimental results show that,the ZSM-5 zeolite with Si/Al ratio of 40 is mixed with pseudo boehmite and activated carbon powder in the mass ratio of 4:3:3 to form a mixture,then the mixture is kneaded,extruded,dried and calcination to prepare the adsorbent carrier,the best calcination temperature is 550?.The adsorbent is modified by equal volume impregnation or kneading method.The adsorbent is characterized by XRD,BET and NH3-TPD.With reagent grade of methyl tert butyl ether as the raw material,the study on the effect of modified components of adsorbent is investigated by static adsorption desulfurization at normal temperature and atmospheric pressure.The experimental results show that,the adsorbent additing of 3w%AgNO₃ by the equal volume impregnation method has better desulfurization performance.Using the prepared adsorbent,with reagent grade of methyl tert butyl ether as the raw material,the study on the process conditions of removing dimethyl disulfideis by adsorption is investigated in the fixed bed dynamic adsorption desulfurization experiment at normal temperature and atmospheric pressure.The experimental results show that,due to the competitive adsorption effect,the water and methanol in the raw materials decrease the ability of the adsorbent to remove dimethyl disulfide.The smaller the space velocity is,the longer the contact time between the adsorbent and the raw material is,the better the desulfurization effect is.When the space velocity of liquid is1 h^-1,the adsorption capacity of the adsorbent is 1.43%.Under the condition of this process,the desulfurization experiment of industrial methyl tert-butyl ether is carried out.The penetration time is 7 h and the sulfur content is 0.33%.Finally,the adsorption isotherm model is fitted.The results showe that the adsorption of dimethyl disulfide adsorbed on the adsorbent is in accordance with the Freundich model.The first order kinetic model is used to fit the adsorption of dimethyl disulfide adsorbed on the adsorbent.