Preparation Of Norbornene And Vinyl Norbornene By Supercritical State In Microchannel Reactor

Norbornene(NB)can be polymerized to form cycloolefin copolymer(COC).COC has the characteristics of high glass transition temperature and high optical clarity,and is widely used in optical and electronic fields.Vinyl norbornene(VNB)is the third monomer of ethylidene propylene rubber,ethylidene norbornene(ENB)intermediate.EPDM rubber is widely used in industrial applications for its excellent weather resistance and ozone resistance.The preparation ofNB and VNB from dicyclopentadiene(DCPD),ethylene or 1,3-butadiene(BD)by Diels-Alder reaction is aconventional synthetic route.In order to improve the selectivity of reaction,this work utilized the supercritical state to entensify the D-A reaction in a microreactor.In the system of synthesizing NB from ethylene and cyclopentadiene(CPD),by adjusting the reaction temperature and the reaction pressure,two molecules(ethylene,CPD)participating in the main reaction were kept in the same phase,and two molecules involved in the side reaction(CPD and DCPD or NB)were located in different phases.As a result,it was possible to enhance the main reaction while suppressing the side reaction.The effect of E/CPD molar ratio was also studied.When E/CPD=14,25MPa,290?,NB synthesis has the best effect,its conversion rate is 99.49%,and the selectivity reaches 99.30%.That is,when CPD and E are in the supercritical phase,the highest liquid NB is synthesized.In the system of BD and CPD synthesis of VNB,the temperature variation near the supercritical point of BD and CPD were investigated.The supercritical carbon dioxide was used as a solvent,mainly to investigate the effect of CO2/BD molar ratio and reaction pressure on the reaction system.When the BD supercritical temperature was exceeded,the amount of thermal decomposition of DCPD into CPD was small,and there was no generation of by-products such as TCPD,VNB,THI,and VOMN.When crossing the CPD supercritical temperature,VCH,OMF,VOMN,and TCPD have a downward trend,indicating that the phase transition of CPD from the liquid phase into the supercritical phase has a great influence on the reaction system.The addition of scCO2 reduced the conversion and selectivity of BD,and the reaction efficiency became worse by the increase in the amount of CO2 added.An increase in pressure accelerated the reaction process of BD and DCPD.While the conversion rate of both reactants increased,the intensification of side reactions also led to the selective decline of DCPD.Finally,the kinetics of BD dimerization was studied in detail in the microreactor,and the corresponding kinetic parameters were obtained by fitting experimental data.The dimerization of butadiene produced 4-hydroxy-cyclohexene(VCH)and 1,5-cyclooctadiene(COD),in which COD was formed only under high temperature conditions.The reaction pressure was found to have a significant effect on the kinetics of butadiene dimerization.