Cracking DCPD Using Hydrogen As Eluent Gas To Produce Ultra-high Purity DCPD

The high purity and ultra-high purity dicyclopentadiene (DCPD) is an important raw to produce high quality unsaturated polyester resins, hydrocarbon resins, ethylene-propylenen diene rubbers and polydicyclopentadiene. In this paper, cracking-rectification-dimerization process is selected for producing ultra-high purity CPD and ultra-high purity DCPD products (purity higher than 99.0%).The process of cracking crude DCPD in the presence of H2 is investigated on a continuous fixed bed reactor. Conditions including cracking temperature, reaction time and H2 to DCPD ratios are studied. The optimal reaction conditions are cracking temperature 320℃, reaction time 4 s and H2 to DCPD ratio of 30 to 50. At these condition, the DCPD conversion reaches 98.0%, while the yield of cyclopentadiene (CPD) is 99.0%. Comparing to the use of N2 or steam as eluent gas, this process is easy and depolymerization temperature is about 30℃lower than using N2. After the crude CPD being obtained, the distillation is adopted to obtain the ultra-high purity CPD products (99.3%), while the yield is 79.0%. Then, The ultra-high purity CPD dimerization process is carried out in an autoclave reactor after distillation process. Factors including the temperature, pressure and reaction time are investigated. The optimal reaction conditions are dimerization temperature 70℃, pressure 1.5 Mpa(psig) and reaction time 1 h. At these conditions, the CPD conversion reaches 92.02%, while the selectivity of CPD is 99.41%. Ultra-high purity DCPD products (99.08%) are obtainned after further separation by the vacuum distillation. The intensification of CPD dimerization by ultrasound irradiation was studied in order to enhance the conversion and the selectivity of CPD dimerization. Kinetic results show that the introduction of ultrasound irradiation could lower the activation energies of the reaction, and also lower the activation energies of the oligomerization of CPD and IP, but not the same degree. The enlarged activation energy difference of the two reactions is the driving force to produce more DCPD in the presence of ultrasound irradiation, and also to improve the conversion of CPD dimerization.