Method for purifying (meth)acrylic acid by oxidising a gaseous substrate
AssigneeArkema France
InventorsMichel Fauconet, Jean-Marie Destenay
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Abstract
The present invention relates to a method for purifying (meth)acrylic acid obtained by oxidizing propane, propylene, acrolein, isobutane, isobutene, ter-butyl alcohol, (meth)acrolein and mixtures thereof by sending the gaseous reaction mixture to the bottom of a countercurrent absorption column (C1) which is supplied at the top with at least one type of hydrophobic heavy solvent, sending the flow (2) from the bottom of column (C1) to a light component separation column (C2) and sending the flow from the base of column (C2), stream (4) to a separation device made up of three sections, exhaustion (S1), concentration (S2) and rectification (S3) respectively in order to extract pure (meth)acrylic acid.”
Claims25
A process for the purification of (meth)acrylic acid from reaction gases obtained by catalytic or redox oxidation of a gas selected from the group consisting of propane, propylene, acrolein, isobutane, isobutene, tertbutyl alcohol, (meth)acrolein and mixture thereof, via extraction in a countercurrent washing of the reaction gases in an extraction column (C1) with at least one heavy hydrophobic solvent fed to the top of the extraction column (C1) and said reaction gases fed to the bottom of said extraction column (C1), characterized in that:
- said extraction takes place in the presence of at least one polymerization inhibitor:
- a separation of the stream (2) obtained at the bottom of the extraction column (C1), which contains the heavy hydrophobic solvent, (meth)acrylic acid and the at least one polymerization inhibitor, is conducted in separation column (C2) whereby a top stream (3) comprising light impurities is sent to the bottom part of the absorption column (C1) and a bottom stream (4) comprising (meth)acrylic acid, heavy hydrophobic solvent and the at least one polymerization inhibitor is sent to the top of a first separation section (S1):
- a separation of stream (4) in first separation section (S1) forms a top gas stream and a bottom stream (9) containing the heavy hydrophobic solvent stripped of the lighter compounds, said stream being recycled as feed to extraction column (C1) directly or after removal of the heavy products contained in stream (9);
- said gas stream obtained at the top of the first section (S1), or a liquid stream generated by the condensation of said gas stream, being sent to the bottom of a second separation section (S2) suitable for concentrating the intermediate heavy compounds of which the boiling point is between that of the one heavy hydrophobic absorption solvent and that of (meth)acrylic acid, and suitable for obtaining a top gas stream and a bottom liquid stream that is sent to the top of the first section (S1):
- said gas stream obtained at the top of the second separation section (S2), or the liquid stream generated by condensation of said gas, being sent to the bottom part of a third separation section (S3) suitable for obtaining a top gas stream which is condensed and partly recycled to the top of said separation section (S3), the remainder being recovered as substantially pure (meth)acrylic acid stripped of the heavy impurities and a bottom liquid stream which is sent to the top of the second separation section (S2).
Dependencies are inferred from the claim text.