(401b) Separation and Purification of Cyclopentadiene and Methyl Cyclopentadiene from Pyrolysis Carbon 9

Nowadays, along with the expansion of ethylene production, the efficient use of by-product of Pyrolysis C9 (Carbon 9) in ethylene production is an important subject to petroleum refining industry. Currently, C9 Distillate Fraction is mainly used as fuel and in making petroleum resin, which causes serious waste because in C9 Distillate Fraction, dicyclopentadiene and methyl cyclopentadiene, with high value-added dimer, cannot be efficiently recycled.

Nowadays, highly pure dicyclopentadiene and methyl ring dicyclopentadiene are mainly obtained from extraction of the Pyrolysis in C5. It's difficult to attain highly pure dicyclopentadiene and methyl ring dicyclopentadiene dimer because the components of the boiling point of C5 are fairly similar to those of the cyclopentadienyl and methyl ring cyclopentadienyl. At the same time, the price of Pyrolysis C9 is lower than that of pyrolysis C5. If the highly pure dicyclopentadiene and methyl ring dicyclopentadiene dimer are separated from Pyrolysis C9, it will meet the rising requirement of CPD, MCPD and their dimers and bring huge economic value.

In this paper, the author analyzes the highly different boiling points of the component in the C9 and cyclopentadiene and methyl cyclopentadiene monomer, and then obtains highly pure cyclopentadienyl and methyl cyclopentadiene by use of the depolymerization of dicyclopentadiene and methyl cyclopentadiene dimer though two consecutive reactive distillation columns. With C9 fraction as raw material, it first enter the depolymerization reaction distillation tower 1, DCPD in the distillation column continuous depolymerized and high-pure CPD obtained from the top of distillation tower, at the same time, the MCPD is enriched in tower kettle in the form of dimer. Then liquid from the tower 1 kettle enters the depolymerization reaction distillation column 2, DMCPD depolymerized in this tower and high-pure MCPD is obtained from the top of distillation tower 2. High-pure cyclopentadiene and methyl cyclopentadiene were obtained individually at the top of two reactive distillation columns. This method will provide a new direction of the comprehensive utilization of C9.

The calculation and designation of cyclopentadienyl and methyl dicyclopentadiene separation columns are based on the small scale experiments of the MCPD and CPD separated from Pyrolysis C9. On the basis of the small scale experiments, by verifying the process of cyclopentadienyl and methyl ring cyclopentadiene produced by depolymerization rectification, the author obtains optimum conditions, and ensures the process of industrialization and technological conditions. Eventually by adopting two reactive distillation columns, the author achieves high purifying products of dicyclopentadiene and methyl ring dicyclopentadiene dimer.

Experiments proved that it is feasible to use byproduct C9 fraction as the raw material to extract high-pure CPD and MCPD in the process of two depolymerized distillation columns. It has promising prospects for industrial development and great economic benefits. CPD>99% of cyclopentadienyl which is obtained from the top of depolymerization distillation column 1, converts into highly pure DCPD product after simple dimerization. And MCPD>97% of methyl cyclopentadienyl which is obtained from the top of depolymerization distillation column 2, converts into highly pure DMCPD product after simple dimerization. CPD yield reaches to 95%, and MCPD yield reaches to 92%.