Research On The Synthesis,Isomerization And Hydrogenation Process Of Acid Anhydride Curing Agent Prepared By Cracking C5

Anhydride is an excellent epoxy resin hardener with high purity and transparency recognized in recent years.It is widely used in electronic packaging and aerospace fields because of its excellent properties such as waterproofing,antifouling,anticorrosion,brightening and gluing.MTHPA and its derivative MHHPA can easily realize the non-toxic and liquefied curing process.However,because the traditional Diels-Alder reaction faces the problems of strong heat release,easy polymerization and unstable product in the batch kettle reactor,the use of microreactor to develop the continuous process of enhanced mass and heat transfer has great advantages to increase the yield.In the development process of liquid MTHPA,the homogeneous catalysis of inorganic acid and base leads to the inevitable purification step.The vacuum distillation at high temperature has high energy consumption and the product is easy to coking.The development of fixed-bed heterogeneous continuous catalysis can greatly save the cost.The preparation of MHHPA is faced with the complex conditions of selective hydrogenation,in which the saturation of double bonds and the ring-opening of anhydride have decisive effects on the quality of the product.The hydrogenation products were analyzed by ¹H-NMR and the specific conditions of catalysts were discussed for the industrial production of MHHPA.To solve the above problems,in this paper,3/4-MTHPA was synthesized by microchannel reactor,in which the mixture of 3-MTHPA and 4-MTHPA was synthesized by D-A reaction with cracking C5,MA and TBC as raw materials.The effects of temperature,reaction time and raw material ratio on D-A reaction in the reactor were discussed.The diameter of 0.5～2.0 mm tube,flow rate（reaction residence time）and mixing ratio of C5 to MA were optimized in the microreactor.Verify the second-order kinetic model of the D-A reaction in the micro inverse interior.Comsol was used for CFD calculation to verify that the strong mass and heat transfer efficiency of the microreactor enhanced the stability of D-A reaction.In this paper,qualitative and quantitative analysis of the synthesized 3/4-MTHPA was carried out by GC and ¹H-NMR,and the conversion efficiency of two different reactors was compared to determine the advantages of continuous flow microchemistry.The 3-4-MTHPA isomerization reaction was studied and the continuous isomerization process was designed.Heterogeneous isomerization catalysts were prepared usingγ-Al₂O₃,Ti-Si molecular sieve,ZSM-5,BETA-30,etc.,and alkaline substances such as K and Na and acidic substances such as P and S as active centers.The X/Al₂O₃ catalysts were characterized by XRD,BET,TEM and other testing methods.The structure and stability of catalyst were determined.Reaction conditions such as reaction temperature,time,catalyst load and dosage were optimized.The optimal reaction conditions for basic catalyst K/Al₂O₃were determined as 150℃,3 h,15%load and 3%dosage,and the optimal reaction conditions for acid catalyst P/Al₂O₃ were 165℃,3 h,10%load and 2%dosage.The continuous isomerization of first base and then acid was achieved by using the catalyst in a fixed bed reactor.The freezing point test showed that the freezing point of 3/4 MTHPA after isomerization decreased to-15℃.Colorless and transparent MHHPA was prepared by hydrogenation of 3/4-MTHPA.Using 3/4-MTHPA as raw material,palladium series and nickel series as catalysts,palladium series had high activity and good catalytic effect.The optimal reaction condition of palladium carbon was tetrahydrofuran as solvent,40℃,1.5 h,1 MPa,2%dosage.The nickel system had poor activity and high reaction conditions of 120℃,2.5 h,2.0 MPa,3.5%.¹H-NMR results showed that the conversion and selectivity of MTHPA catalyzed by palladium carbon was 100%.The conversion and selectivity of MTHPA catalyzed by skeleton nickel were 100%and 99.34%respectively.The obtained MHHPA was colorless,transparent and had a freezing point-15℃.