The Key Technologies Of Ethylene Glycol Ethyl Ether Synthesized By Ethylene Glycol With The Direct Method

Ethylene glycol ether is a widely used organic intermediate and solvent with good performance.The conventional synthetic method is from ethylene oxide as raw material.This thesis focused on the synthesis of ethylene glycol ethyl ether?EGEE?with ethylene glycol?EG?and ethanol?EtOH?as starting material.The reaction conditions were systematically investigated through chemical thermodynamic calculation,The catalysts were designed and prepared,and the reaction conditions of synthetic were optimized.The main work of this thesis were as follows:Part One: The equilibrium composition of the product system under different temperature,pressure and feed ratio were calculated by Aspen Plus.The obtained results showed that the yield of ethylene glycol monoethyl ether?EGMEE?increased firstly and then decreased as the temperature rising,however the ethylene glycol diethyl ether?EGDEE?decreased continuously.220? turned to be the best choice.High ratio of EtOH to EG was favorable to the generation of EGMEE,EGDEE and ether,and inhibited the transformation to diethylene glycol?DEG?and 1,4-dioxane.High reaction pressure was conducive to balance to generate low vapor pressure material direction,and is favorable to the formation of EGMEE and EGDEE.But little effect on the conversion and selectivity of this transformation was observed when the pressure more than 3 MPa.The thermodynamic equilibrium constants of the reactions were calculated through chemical thermodynamic method at different temperature under ideal gas state.The obtained reaction enthalpies??rH?were all negative,which indicated that low temperature was helpful for preparation of EGDEE.Part Two: The catalytic activity of different Lewis acid,Br?nsted acid,Lewis base and metal salts with acid and alkali sites was investigated by single factor method.The results showed that catalyst with higher acidity performed higher activity.Catalyst with both acidic and basic sites showed good selectivity for ethylene glycol ether.Among Lewis acid,the complex of BF3 gave the best catalytic performance,but poor selectivity.Overall,anhydrous AlCl3 proved to be the best Lewis acid catalyst.Under the conditions of n?EtOH?:n?EG?was 4:1,reaction time was 4 h,reaction temperature was 260?,reaction pressure 7 MPa and fixed catalyst is 4%?wt?,EGEE was obtained with highest yield.And the conversion of EG was 38.8% and the selectivity of EGMEE was 59.9%.Using compound catalyst of Al Cl3 and Na2HPO4 was helpful for the selectivity of EGEE,owing to the presence of both acidic and basic sites on the complex catalyst.Further study showed that satisfactory results could be obtained when the ratio of n?AlCl3?:n?Na2HPO4?was 1:3,giving that the conversion of EG was 25.1% and the selectivity of EGMEE could be up to 72.3%.Part Three: The catalytic activity of modified HZSM-5 catalysts prepared by different methods were studied.The results showed that the HZSM-5 with Si/Al ratio 25,modified by excessive impregnation method with 0.5 mol?L-1 ammonium sulfate aqueous solution,and calcined at 500? for 4 h,has the highest activity than other modified molecular sieves.The reaction temperature could be reduced to 180?.The morphology,structure and property of HZSM-5 molecular sieves were characterized by scanning electron microscope?SEM?,energy dispersive spectrometer?EDS??X-ray diffraction?XRD??BET?NH3-TPD and TG-DTG.The results showed that sulfur element was introduced on the surface of modified HZSM-5 molecular sieves,new super acidic sites and less specific surface area and average pore diameter were observed.Then the reaction conditions were optimized by the orthogonal experiment and single factor method.Based on the experiment,the optimal reaction condition was performed with 2% catalyst?wt?at 180? under 7 MPa pressure for 4 hours.The conversion of EG was 68.8%,the selectivity of EGEE was 92.4%,the yield of EGEE could reach 63.6%,close to the yield at 200?,with much less side reactions.The reaction of EG and EtOH on the catalyst is a first order reaction,the activation energy Ea is 77.42 kJ?mol-1 and the preexponential factor k0 is 1.844×107 s.Part Four: The morphology,structure,surface element,surface acidicity and changement of aperture size of modified HZSM-5 catalysts were characterized by XRD,NH3-TPD,FTIR,SEM,EDS,BET and TG-DTG.The results showed that the deactivation was mainly caused by catalyst pore blockage and loss of surface acidic sites which were result from carbon deposition.Delightedly,catalyst could be regenerated through calcinations at above 450? in the presence of oxygen by removal of the deposited carbon.Part Five: The catalytic activity of phosphotungstic acid,phosphomolybdic acid,silicotungstic acid and their salts in the transformation of EG to EGEE was investigated.These experiments showed that the catalyst derived from Cs_0.66Ag_0.33H₂PW₁₂O₄₀ gave the best catalytic performance after calcined at 300? for 4 h.And its structure was characterized by XRD,Zeta Plus and EDS.Classical Keggin structure was observed in Ag3PW12O40 and Cs2AgPW12O40.The average particle size of Cs_0.66Ag_0.33H₂PW₁₂O₄₀ prepared by neutralization precipitation was 68 nm,which showed goof redispersion.High to 560? was necessary to destroy the Keggin structure,that proved to be high thermal stable.Under the following conditions: n?EtOH?:n?EG?= 4:1,reaction temperature 200?,reaction pressure 7 MPa,reaction time 4 h,load of catalyst 0.8%,the conversion of EG?GC?reached 96.2%,selectivity of EGMEE and EGDEE?GC?reached 49.3% and 48.6% respectively,the total yield of EGEE?GC?was 94.1%,that is close to the equilibrium value calculated by thermodynamic method.The Cs_0.66Ag_0.33H₂PW₁₂O₄₀ nanoparticles formed with 60⁸0 mesh size after pressing,crushing and sieving when using gas phase SiO₂ as binder.The obtained catalyst showed high stability to water and ethanol.The best molding process was 25 MPa,and compression kept for 30 min.The catalyst could participate in reaction for 100 h in the fixed bed with no obvious loss in catalytic activity.