Analysis Of Cracking C₅ Fraction And Reaction Kinetics Of Dienes/Maleic Anhydride

Cracking C₅ fraction is the by-product of the cracked petroleum. Cracking C₅ comprises more than twenty components in which isoprene(IP), cyclopentadiene(CPD) and piperylene(PIP) are three most important components. C₅ fraction can be utilized directly without being separated, but benefit is less. In order to utilize the primary components isoprene, cyclopentadiene and piperylene efficiently, the appropriate method for separation should be selected to gain pure monomer.On the background of the separation of C₅ fraction, in order to apply the separation technology of C₅ fraction to industrial production conveniently, the method for analysis of whole C₅ fraction and the method for analysis of trace cyclopentadiene contained in isoprene by GC were established. On other hand, the reaction kinetics of CPD, IP and maleic anhydride(MAH) were also studied. The main contents and results of the paper are as follows:1. Packed column 5MNMP and capillary column SE-30 were applied to analysis of whole C₅ fraction. Applicability in the analysis of C₅ fraction of the two columns was compared. Because of lower column temperature, longer analysis period being needed and dicyclopentadiene not being detected, the packed column is not very appropriate to industrialization. Because of good repeatability, reliable results and short analysis period, the components being fully separated once, SE-30 capillary column satisfy the analysis requirement of quality control and production process control of cracking C₅. SE-30 column also can be applied to other chemicals concerned in C₅ fraction separation process. For example, it can be used to analysis of extractant dimethyl formamide and MAH.2. A method for analysis of trace cyclopentadiene impurity in isoprene by GC using splitless injection and capillary column SE-30 was established. The optimum operation conditions were found as follows: injection temperature 140°C; column temperature 30°C; volumes of sample 1.0μL; splitless period 0.5min⁰.6min. The results showed that the minimum detectable limit for the concentration ofcyclopentadiene in isoprene by this method was about O.lmg/kg. The average relative standard deviation for an isoprene sample with about lmg/kg cyclopentadiene impurity is 4.1% and the maximum deviation is 6.0%. The time for one run is about 8min. The method meets the identification of polymerization grade isoprene.3. Reaction kinetics of CPD-MAH, IP-MAH and CPD-IP-MAH were studied. The reaction rate constants of different systems were gained. The optimum reaction temperature for removal of CPD from IP is 20 °C. The selectivity of CPD-MAH is higher than IP-MAH. In the range of temperature 0³0°C, the reaction rate constants of CPD-MAH is 2-3 order of magnitude times higher than those of IP-MAH. So the reaction rate constants can be applied to the reaction of removing minim cyclopentadiene impurity from isoprene.To sum up, the capillary column SE-30 satisfy the analysis requirement of quality control and production process control of cracking C5. It has good industry future that the MAH is applied to removing minim cyclopentadiene impurity from isoprene.