Method for purifying light acrylates
AssigneeArkema France
InventorsKevin COULET, Serge TRETJAK
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Abstract
The present invention relates to the production of light (meth)acrylic esters, such as methyl or ethyl (meth)acrylate, by direct esterification of (meth)acrylic acid by the corresponding light alcohol. A subject matter of the invention is more particularly a process for the recovery/purification of C1-C2 alkyl acrylate comprising steps of evaporation and of partial condensation making it possible to remove a fraction rich in alkyl alkoxypropionate byproduct, which cannot be upgraded by a cracking process and which is very difficult to remove whether this is when it is pure, because it is close in boiling point to that of acrylic acid, or when it is in the form of an azeotrope with water, because it is close in boiling point to that of the acrylic ester.
Claims18
A process for the recovery and/or purification of C1-C2 alkyl acrylate from a reaction mixture resulting from esterification of acrylic acid with an alcohol chosen from methanol and ethanol carried out in the presence of polymerization inhibitor(s), said process comprising the following steps:
- azeotropic distillation of said reaction mixture in a first distillation column, resulting in the separation:
- at the top of the first distillation column, of a top stream comprising the C1-C2 alkyl acrylate, unreacted alcohol and water;
- at the bottom of the first distillation column, of a bottom fraction comprising unreacted acrylic acid and heavy products,
- treatment of the top stream from the first distillation column by liquid/liquid extraction, generating an aqueous phase comprising alcohol and an organic phase rich in alkyl acrylate;
- treatment of said organic phase rich in alkyl acrylate in a fourth distillation column to separate:
- at the top of the fourth distillation column, purified alkyl acrylate and,
- at the bottom of the fourth distillation column, heavy products and the polymerization inhibitors, and
- continuous treatment of the bottom stream of the fourth distillation column, by evaporation, and at least two successive condensations of a gas phase resulting from the evaporation, to obtain:
- an alkyl acrylate stream;
- an alkyl alkoxypropionate stream, and
- a residue containing the polymerization inhibitors.
Dependencies are inferred from the claim text.