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US 4,232,182 AGranted
Process for purifying isoprene
AssigneeNone recorded
InventorsAlexandr G. Liakumovich, Boris I. Pantukh, Tatyana M. Lesteva
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AssigneeNone recorded
InventorsAlexandr G. Liakumovich, Boris I. Pantukh, Tatyana M. Lesteva
Estimating the term…
A process for purifying isoprene produced by catalytic decomposition of dimethyldioxane from carbonyl compounds and cyclopentadiene which involves passing isoprene at a temperature of 40.degree. to 70.degree. C. through a bed of a solid product such as an anion exchange resin or alkali (the latter may be used with or without an inert carrier), followed by subjecting the isoprene to close fractionation performed with at least 50 theoretical plates and at a reflux ratio of at least 3. The process of the present invention enables practically complete purification of isoprene from carbonyl compounds and cyclopentadiene. The purified isoprene, when used as a monomer in the production of stereospecific isoprene rubber, results in high-quality products; and reduces by a factor of 2-3 the Ziegler catalyst consumption in the isoprene rubber synthesis.
A process for purifying isoprene produced by catalytic decomposition of dimethyldioxane from carbonyl compounds and cyclopentadiene which consists of the steps of passing isoprene at a temperature of from 40.degree. to 70.degree. C. through a bed of a solid product selected from the group consisting of an anion exchange resin and alkali, and subjecting said isoprene to close fractionation on at least 50 theoretical plates and at a reflux ratio of at least 3 recycling 20 to 80 wt.% of said purified isoprene following close fractionation for admixture with the starting isoprene to be purified.
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With five carbon atoms: isoprene
Purification; Separation; Use of additives: processes comprising at least two steps in series
Purification; Separation; Use of additives: by distillation
Purification; Separation; Use of additives: by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with…
Term ended 4 Nov 1997 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to processes for purifying isoprene produced by catalytic decomposition of dimethyldioxane from carbonyl compounds and cyclopentadiene. The isoprene thus purified is used as a monomer in the production of stereospecific isoprene rubber.
2. Description of the Prior Art
For a better understanding of the present invention, the following examples illustrating the process of isoprene purification are given hereinbelow.
Isoprene produced by catalytic decomposition of dimethyldioxane and containing 0.2 wt.% of carbonyl compounds and 0.05 wt.% of cyclopentadiene was heated to 60.degree. C. and passed at the space velocity of 1 hr..sup.-1 through a vertical cylindrical reactor filled with solid potassium hydroxide having a particle size of 5 to 30 mm. Isoprene discharged from the reactor contained 0.0005 wt.% of carbonyl compounds and 0.0004 wt.% of cyclopentadiene. From the reactor the isoprene was delivered into a close-fractionation column having 50 theoretical plates, the reflux ratio being equal to 3. Purified isoprene was discharged from the column top. The content of carbonyl compounds in the purified isoprene was 0.00005 wt.% and that of cyclopentadiene was 0.00005 wt.%.
Isoprene produced by catalytic decomposition of dimethyldioxane and containing 0.15 wt.% of carbonyl compounds and 0.1 wt.% of cyclopentadiene was heated to 50.degree. C. and passed at the space velocity of 1.5 hr..sup.-1 through a vertical cylindric reactor filled with a finely divided anion exchange resin (reaction product of chloromethylated copolymer of styrene and divinylbenzene with trimethylamine) having a particle size of 1-3 mm. The content of the carbonyl compounds in the isoprene discharged from the reactor was 0.0003 wt.%, and the cyclopentadiene content in the discharged isoprene was 0.0005 wt.%. From the reactor the isoprene was delivered into a close-fractionation column having 55 theoretical plates and a reflux ratio of 4. Purified isoprene was discharged from the column 20 wt.% of the purified isoprene was continuously recycled for mixing with the starting isoprene fed into the the anion exchange resin filled reactor. In the isoprene thus purified there were practically no microimpurities (carbonyl compounds and cyclopentadiene).