Application Of Microreactor In Ring Opening Reaction Of The Cyclic Compounds

Microreactor,a microchannel reactor,is one with a micron-level fluid channel made by means of special micromachining techniques.Compared with the conventional reactors,microreactors exhibit better heat transfer and mass transfer due to their internal microstructures with extremely large specific surface area.Therefore,the microreactor has rapidly attracted much attention of experts in related fields.In this paper,the microreactor is applied to the ring-opening reaction of cyclic compounds such as alkylene oxide and organic carbonates.It aims to use the microreactor,with the advantages of fast heat transfer and mass transter,for improving the conversion rate and product selectivity.The thesis deals with:The coupling reaction of alkylene oxide and carbon dioxide is realized in high efficiency by microreactor,using a binary catalytic system composed of metal aluminum complex and quaternary ammonium salt.The effects of reaction temperature,carbon dioxide pressure,molar ratio of reactants and residence time were investigated by using epichlorohydrin(ECH)as the model substrate.The optimum reaction conditions were as follows: temperature 160 oC,pressure 2.0 MPa,ECH/CO2 molar ratio 1:2,reaction residence time 45.1 s.Under this condition,the conversion of ECH was greater than 99% and the selectivity of cyclic carbonate was more than 99%.Compared with the conventional reaction,the process has the advantages of short residence time,high conversion rate,small amount of carbon dioxide and stable production.Homogeneous catalyst mediated the esterification of cyclic carbonate and methand to prepare dimethyl carbonate usually suffers from low conversion,the poor selectivity and difficult sepration of catalyst from the reaction mixture.Aiming at these problems,a free-catalyst and green synthesis of dimethyl carbonate was developed by the use of microreactor.The optimum reaction conditions were as follows: the temperature was 250 oC,the molar ratio of propylene carbonate to methanol was 1: 8,and the reaction time was 13.2 min.Under these conditions,the conversion of propylene carbonate is 41% and the selectivity of dimethyl carbonate is up to 95%.Compared with the conventional methods used in industrial production,this process has the advantages of high product selectivity,low methanol consumption and no need to separate the catalyst.