Process for production of (meth)acrylic acid with high boiling fraction work-up by means of crystallization
View Patent ↗A process for production of (meth)acrylic acid is disclosed. The process includes synthesizing and distillatively working-up a crude (meth)acrylic acid phase to obtain a (meth)acrylic acid phase and a dimer phase including (meth)acrylic acid dimers and/or (meth)acrylic acid oligomers. At least a part of the (meth)acrylic acid dimers and/or of the (meth)acrylic acid oligomers from the dimer phase is split to obtain a (meth)acrylic acid including a low-boiling phase and a high-boiling phase including less (meth)acrylic acid than the low-boiling phase. At least a part of the (meth)acrylic acid from the low-boiling phase is separated by forming of one or more crystals to obtain a pure (meth)acrylic acid and a residue. Also disclosed is a device for production of (meth)acrylic acid, a process for production of a polymer as well as chemical products based on or including (meth)acrylic acid or a polymer as well as the use of (meth)acrylic acid or polymers in chemical products.
1. A process for production of (meth)acrylic acid, comprising the steps of:
a) synthesizing a crude (meth)acrylic acid phase wherein crude (meth)acrylic acid comprises from about 1 to about 80 wt % of (meth)acrylic acid;
wherein said synthesizing a crude (meth)acrylic acid phase is selected from the group consisting of gas phase oxidation, dehydration of an organic molecule having at least one OH-group wherein the organic molecule is selected from the group consisting of glycerine, lactic acid and β-hydroxypropionic acid, optionally followed by an oxidation, and liquid phase oxidation
b) distillatively working-up the crude (meth)acrylic acid phase to obtain:
a (meth)acrylic acid phase, and
a dimer phase comprising (meth)acrylic acid dimers or (meth)acrylic acid oligomers or both;
c) splitting at least a part of the (meth)acrylic acid dimers or of the (meth)acrylic acid oligomers or both from the dimer phase to obtain:
a (meth)acrylic acid-comprising a low boiling phase, and
a high boiling phase comprising less (meth)acrylic acid than the low boiling phase; wherein said high boiling phase is discarded;
d) separating at least a part of the (meth)acrylic acid from the low boiling phase by forming one or more crystals to obtain:
a pure (meth)acrylic acid, and
a residue.
2. A process according to claim 1 , wherein at least a part of the low boiler phase in step d) is provided as fluid film over a cold source.
3. A process according to claim 2 , wherein at least a part of the fluid film comprises a falling film.
4. A process according to claim 2 , wherein the cold source comprises an at least partially planar form.
5. A process according to claim 1 , wherein at least a part of the crystals are subjected to a sweating.
6. A process according to claim 5 , wherein the crystals are melted after the sweating.
7. A process according to claim 1 , wherein the distillative work-up according to step b) occurs in at least two distillation steps following each other.
8. A process according to claim 1 , wherein the splitting according to step c) occurs thermally.
9. A process according to claim 8 , wherein the splitting according to step c) occurs under a pressure which is different from the ambient pressure.
10. A process according to claim 1 , further comprising the step of e) crystallizing the residue of step d) into
a (meth)acrylic acid-rich phase, and
an impurity phase.
11. A process according to claim 10 , wherein the (meth)acrylic acid-rich phase is at least partially supplied to process step d).