Process for preparing acrylic acid purified by crystallization from hydroxypropionic acid and apparatus therefore
First Claim
1. A process for the preparation of acrylic acid wherein the acrylic acid is made from a fluid F1 containing a hydroxyproprionic acid wherein said fluid F1 is obtained by a process comprising the process steps of i) preparation of hydroxypropionic acid from carbohydrates to give an aqueous phase containing hydroxypropionic acid and solids including microorganisms, and ii) separating off of the solids from said aqueous phase, wherein the process comprises the process steps:
- (a1) provision of said fluid F1 containing a hydroxypropionic acid;
wherein said fluid F1 is aqueous, and has a composition comprising(C1-1) from about 5 to about 20 wt. % of hydroxypropionic acid, salts thereof, or mixtures thereof,(C1-2) from about 0.1 to about 5 wt. % of inorganic salts,(C1-3) from about 0.1 to about 30 wt. % of organic compounds which differ from hydroxypropionic acid,(C1-4) from 0 to about 50 wt. % of solids, and(C1-5) from about 20 to about 90 wt. % of water,wherein the sum of components (C1-1) to (C1-5) is 100 wt. %;
(a2) dehydration of said hydroxypropionic acid to give a fluid F2 containing acrylic acid wherein the dehydration comprises a reactive distillation and the dehydration is carried out in a CO2 atmosphere, or an inorganic acid, or both; and
(a3) purification of said fluid F2 containing acrylic acid by crystallization to give a purified acrylic acid phase wherein said purified acrylic acid phase comprises acrylic acid having a purity of at least 70 wt. %.
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Abstract
The invention relates to a process for the preparation of acrylic acid and a process for the preparation of polyacrylic acid comprising the process steps: (a1) preparation of 3-hydroxypropionic acid from a biological material to give a fluid, in particular aqueous, phase containing 3-hydroxypropionic acid; (a2) dehydration of the 3-hydroxypropionic acid to give a fluid, in particular aqueous, solution containing acrylic acid; (a3) purification of the solution containing acrylic acid by a suspension crystallization or a layer crystallization to give a purified phase; and corresponding devices for carrying out these processes, and acrylic acid and polyacrylates. The invention is distinguished in that acrylic acid and polyacrylates can thereby be prepared efficiently, inexpensively, and sustainably with simple means and with a high purity on the basis of regenerable raw materials.
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Citations
13 Claims
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1. A process for the preparation of acrylic acid wherein the acrylic acid is made from a fluid F1 containing a hydroxyproprionic acid wherein said fluid F1 is obtained by a process comprising the process steps of i) preparation of hydroxypropionic acid from carbohydrates to give an aqueous phase containing hydroxypropionic acid and solids including microorganisms, and ii) separating off of the solids from said aqueous phase, wherein the process comprises the process steps:
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(a1) provision of said fluid F1 containing a hydroxypropionic acid; wherein said fluid F1 is aqueous, and has a composition comprising (C1-1) from about 5 to about 20 wt. % of hydroxypropionic acid, salts thereof, or mixtures thereof, (C1-2) from about 0.1 to about 5 wt. % of inorganic salts, (C1-3) from about 0.1 to about 30 wt. % of organic compounds which differ from hydroxypropionic acid, (C1-4) from 0 to about 50 wt. % of solids, and (C1-5) from about 20 to about 90 wt. % of water, wherein the sum of components (C1-1) to (C1-5) is 100 wt. %; (a2) dehydration of said hydroxypropionic acid to give a fluid F2 containing acrylic acid wherein the dehydration comprises a reactive distillation and the dehydration is carried out in a CO2 atmosphere, or an inorganic acid, or both; and (a3) purification of said fluid F2 containing acrylic acid by crystallization to give a purified acrylic acid phase wherein said purified acrylic acid phase comprises acrylic acid having a purity of at least 70 wt. %. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification