(Meth)acrylic acid production process
The invention relates to the production of (meth)acrylic acid, and to implementation of a step of condensing water contained in a recycled gas effluent and/or in the air feed in a (meth)acrylic acid production process, which further includes a process for purifying a reaction mixture comprising (meth)acrylic acid without using azeotropic solvent and based on the use of two distillation columns.
1. A process for production of (meth)acrylic acid, comprising at least the following steps:
i) subjecting at least one (meth)acrylic acid precursor to gas-phase oxidation in the presence of an air feed so as to form a gas reaction mixture comprising (meth)acrylic acid;
ii) cooling the gas reaction mixture;
iii) subjecting the gas reaction mixture to dehydration without using azeotropic solvent in a dehydration column, resulting in a first top gas stream and in a first bottom stream;
iv) at least partly subjecting the first top gas stream distilled at the top of the dehydration column to condensation in a top condenser to form condensate, the condensate being returned to the dehydration column in reflux form to absorb acrylic acid, and at least partly returning gas effluent to the oxidation reaction, and subjecting a remainder to thermal and/or catalytic oxidation;
v) at least partly subjecting the first bottom stream from the bottom of the dehydration column to distillation in a finishing column, resulting in a second top stream, and in a second bottom stream containing heavy compounds;
vi) recovering (meth)acrylic acid stream by drawing off (meth)acrylic acid from a side of the finishing column;
and further applying a water condensation step to at least one of two streams selected from the group consisting of: the air feed for the oxidation reaction of step i), and the gas effluent at an outlet of the top condenser of step iv) which is recycled to the oxidation reaction.
2. The process according to claim 1 , wherein the water condensation step is carried out using a single condenser for the two streams or using a condenser for each of the two streams.
3. The process according to claim 1 , wherein the water condensation step is carried out at a temperature ranging from 15° C. to the temperature of the condenser at the top of the dehydration column.
4. The process according to claim 1 wherein the step of condensing the water for the recycled gas effluent is carried out at a temperature of between 40° C. and 60° C.
5. The process according to claim 1 wherein the step of condensing the water for the air feed is carried out at a temperature of between 15° C. and 25° C.
6. The process according to claim 1 wherein the condensed water from the air feed is at least partly recycled to water cooling towers.
7. The process according to claim 1 wherein the condensed water is partly used to prepare aqueous solutions of polymerization inhibitors.
8. The process according to claim 1 wherein the condensed water is partly flushed and sent to the treatment of wastewater, or subjected to a thermal oxidation treatment.
9. The process according to claim 1 wherein the (meth)acrylic acid precursor is acrolein, obtained by oxidation of propylene or by oxydehydrogenation of propane.
10. The process according to claim 1 wherein the (meth)acrylic acid precursor is methacrolein obtained by oxidation of isobutylene and/or of tert-butanol or from oxydehydrogenation of butane and/or isobutane.
11. The process according to claim 1 wherein the (meth)acrylic acid precursor is derived from glycerol, from 3-hydroxypropionic acid or from 2-hydroxypropanoic acid.
12. The process according to claim 1 wherein the (meth)acrylic acid is acrylic acid and the acrylic acid precursor is acrolein obtained by catalytic oxidation of propylene.