| 摘要 |
The invention relates to a method whereby an initial FCC C5 fraction is used to obtain a final, purified, isoprene-enriched C5 fraction which can be used for the selective polymerisation of isoprene, and a method of obtaining a homopolymer of isoprene from a polymerisation medium comprising isoprene and at least one methyl butene, such as the aforementioned purified, isoprene-enriched FCC C5 fraction. The method of obtaining the final fraction from the initial C5 fraction comprises the following steps: a dehydrogenation reaction which is applied to an intermediate C5 fraction, said fraction comprising methyl butenes and originating from the initial fraction, and which produces the final fraction; and purification of the final fraction thus obtained in order to obtain the final, purified fraction which is virtually free of disubstituted alkynes, terminal alkynes and cyclopentadiene. Moreover, the mass fraction of methyl butenes in the intermediate fraction is < 30 %. According to the invention, the method of obtaining a hompolymer of isoprene consists in reacting a catalytic system based on a conjugated diene, a rare earth salt of a suspended organic phosphoric acid, an alkylation agent, the molar ratio (alkylation agent/salt) varying between 1 and 5, and a halogen donor, in the presence of isoprene and at least one methyl butene at a mass ratio (methyl butene(s)/isoprene) of >/= 50 %,
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