Process for producing (meth)acrylic acid

1. A process for recovering (meth)acrylic acid without using azeotropic solvent, starting from a gaseous reaction mixture comprising (meth)acrylic acid obtained by gas-phase oxidation of a precursor of the (meth)acrylic acid, comprising at least the following steps:

i) subjecting the gaseous reaction mixture to dehydration without using azeotropic solvent in a dehydration column, resulting in a dehydration column overhead stream, at least a portion of which is condensed and sent back to the dehydration column in the form of reflux, and in a dehydration column bottom stream;

ii) subjecting the dehydration column bottom stream, at least in part, to a distillation at a pressure below atmospheric pressure in a finishing column, resulting in a finishing column overhead stream and in a finishing column bottom stream containing heavy compounds;

iii) recovering a (meth)acrylic acid stream by drawing off as a sidestream from the finishing column, and/or as bottoms from the finishing column;

subjecting the finishing column overhead gaseous stream, at least in part, to a dry vacuum pump condensation system such that the finishing column operates under vacuum, thereby eliminating or reducing generation of aqueous discharge and forming a condensate comprising light compounds that is recycled back to the dehydration column, and a final gaseous effluent.

2. The process according to claim 1 , wherein the dry vacuum pump condensation system comprises at least one condenser and one dry vacuum pump.

3. The process according to claim 1 wherein the dry vacuum pump condensation system additionally comprises a liquid separator, or one or more flame traps, or one or more filters, or sealing and insulating systems, or a dry booster pump or a combination of dry booster pumps.

4. The process according to claim 1 wherein at least one portion of the (meth)acrylic acid stream drawn off as a sidestream is subjected to a dry vacuum pump condensation system, identical to or different from that used for the finishing column overhead stream from the finishing column.

5. The process according to claim 1 wherein the precursor of the (meth)acrylic acid is acrolein, obtained by oxidation of propylene or by oxydehydrogenation of propane.

6. The process according to claim 1 wherein the precursor of the (meth)acrylic acid is methacrolein, obtained by oxidation of isobutylene and/or of tert-butanol or from oxydehydrogenation of butane and/or isobutane.

7. The process according to claim 1 wherein the precursor of the (meth)acrylic acid comprises carbon of renewable origin.

8. The process according to claim 7 wherein the precursor of the (meth)acrylic acid is derived from glycerol, 3-hydroxypropionic acid or 2-hydroxypropanoic acid.

9. The process according to claim 1 further comprising the step of purifying the (meth)acrylic acid stream recovered in step iii).

10. The process for producing (meth)acrylic acid comprising at least the following steps:

A) subjecting at least one (meth)acrylic acid precursor to gas-phase oxidation to form a gaseous reaction mixture comprising (meth)acrylic acid;

B) cooling the gaseous reaction mixture;

C) subjecting the cooled gaseous reaction mixture to the process for recovering (meth)acrylic acid as recited in claim 1 .

11. The process according to claim 10 , wherein the (meth)acrylic acid is acrylic acid and the acrylic acid precursor is acrolein obtained by catalytic oxidation of propylene.

12. A system for recovering (meth)acrylic acid without using azeotropic solvent according the process of claim 1 , comprising at least:

a) one dehydration column;

b) one finishing column fluidically connected to the bottom of said dehydration column;

c) at least one dry vacuum pump condensation system, fluidically connected to the top of said finishing column;

d) optionally one dry vacuum pump condensation system fluidically connected laterally to said finishing column.