Ethylidene Norbornene Production

The process under analysis comprises four major sections: (1) Thermal Cracking; (2) Diels-Alder Reaction; (3) VNB Purification; and (4) Isomerization.

(1) Thermal Cracking. Fresh and recycled dicyclopentadiene (DCPD) streams are mixed and fed to a stirred tank reactor filled with diphenylether. Upon contact with the reaction medium, the DCPD quickly reaches the high temperature required to trigger the dimer's thermal cracking and produces cyclopentadiene (CPD). The reactor has a reflux condenser coupled to its top exit, which ensures that only the evaporated CPD produced leaves to proceed to the Diels-Alder reaction step, while via a side exit the reactors liquid medium is continuously fed to a distillation column responsible for removing the tetrahydroindene (THI) by-product.

(2) Diels-Alder Reaction. The CPD produced is then fed to a tubular reactor along with butadiene to react and produce 5-vinyl-2-norbornene (VNB) as well as the by-products 4-vinylcyclohexene (VCH), THI, DCPD, and oligomers. The reactor's outlet stream is fed to a distillation column where the unreacted reactants are recovered as distillate and recycled to the reactor along with the solvent (toluene), while the products come out as the bottom stream and proceed to purification downstream.

(3) VNB Purification. The reaction products go through three distillation columns. The first one is responsible for removing VCH. In the second column, the main reaction product, VNB, is separated from the heavy impurities and sent to the isomerization reactor downstream. In the third column, the produced DCPD and THI are separated from the oligomers and recycled to the thermal cracking reactor.

(4) Isomerzation. The purified VNB is then fed to a tubular fixed bed reactor packed with catalyst where it is converted into the target product, 5-Ethylidene-2-Norbornene (ENB).