Method for preparing polymerization-grade isoprene

Abstract

The invention discloses a method for preparing polymerization-grade isoprene. The method comprises the following steps: (1) feeding a light carbon-5 raw material of which cyclopentadiene is removed through pretreatment into a separation tower, performing extraction distillation, separating an extraction agent, removing light carbon-5 in the raw material, and recycling an extraction agent; (2) distilling the raw material rich in isoprene obtained in the step (1) so as to separate and remove recombinant component impurities, and collecting a chemical-grade isoprene product from a tower top; (3)continuously refining chemical-grade isoprene obtained in the step (2), and obtaining crude isoprene with components such as butyne-2, and crude isoprene with components such as valylene and cyclopentadiene from the tower top; and (4) performing light component removal on the crude isoprene obtained from the tower top in the step (3), and obtaining a polymerization-grade isoprene product from a side line. Compared with the prior art, the method disclosed by the invention has the advantages that the retention time of isoprene in the separation process is shortened, the loss of isoprene is reduced, meanwhile equipment investment and separation energy consumption are reduced, and remarkable economic benefits are made.

Description

technical field [0001] The present invention relates to a method for preparing polymer-grade isoprene, in particular to the use of the C5 fraction pretreated to remove cyclopentadiene from the by-product of petroleum cracking to produce ethylene as a raw material, using extractive distillation and solvent separation A method for isolating polymer grade isoprene is carried out simultaneously. Background technique [0002] The cracked carbon five (C5) fraction is a by-product in the process of cracking naphtha and other heavy hydrocarbons to produce ethylene, and its content is about 12% to 20% of the ethylene output. The C5 fraction is mainly composed of alkanes, monoolefins, diolefins and alkynes, among which isoprene (IP), piperylene (PD) and cyclopentadiene (CPD) are more abundant, accounting for about C5 fraction output 40% to 60% of that. Isoprene accounts for 15%-25% of the C5 fraction. It is widely used in the production of synthetic rubber, pharmaceutical and pestic...

AI Technical Summary

Problems solved by technology

But its biggest disadvantage is that the obtained product is an azeotrope of isoprene and n-pentane, and it is impossible to obtain isoprene with higher purity. Further purification and regeneration require higher trays and larger reflux than, economically uneconomical

[0008] It can be seen that in the prior art, the problems of energy consumption, isoprene yield and purity cannot be taken into account when preparing polymer grade isoprene by using the C5 fraction produced by the by-product of petroleum cracking to produce ethylene.

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