Process for the production of (meth)acrylic acid and derivatives and polyers produced therefrom
A method of extracting (meth)acrylic acid from an aqueous reaction medium into an organic phase in contact therewith is described. The aqueous reaction medium is formed from at least one base catalyst and at least one dicarboxylic acid selected from maleic, fumaric, malic, itaconic, citraconic, mesaconic, and citramalic acid or mixtures thereof in aqueous solution and contains the base catalysed decarboxylation products of the base catalysed reaction. The method includes either the addition of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the aqueous reaction medium to enhance the solvent extraction of the (meth)acrylic acid into the organic solvent or maintaining the level of base catalyst to dicarboxylic acid and/or pre-cursor at a sub-stoichiometric level during the extraction process. The method extends to a process of producing (meth)acrylic acid, its esters and polymers and copolymers thereof.
1. A method of extracting (meth)acrylic acid from an aqueous reaction medium, the aqueous reaction medium being formed from at least one base catalyst and at least one dicarboxylic acid selected from maleic, fumaric, malic, itaconic, citraconic, mesaconic, and citramalic acid or mixtures thereof in aqueous solution and containing the base catalysed decarboxylation products thereof including (meth)acrylic acid and/or (meth)acrylate base salt, the method comprising the steps of introducing an organic solvent to the said aqueous reaction medium for solvent extraction of the (meth)acrylic acid into an organic phase wherein the method is characterised in that there is added an additional amount of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the said aqueous reaction medium to enhance the solvent extraction of the (meth)acrylic acid into the organic solvent.
2. A method according to claim 1 , wherein the concentration of (meth)acrylic acid in the aqueous phase extraction is at least 0.05 mol dm -3 .
3. A method according to claim 1 , wherein the molar level of base catalyst to the said at least one dicarboxylic acid and/or pre-cursor thereof is maintained at a sub-stoichiometric level in relation to the formation of the first acid salt thereof during the extraction process and the amount of dicarboxylic acid added is determined accordingly.
4. A method according to claim 1 , wherein the dicarboxylic acid and/or a pre-cursor thereof is selected from citric, itaconic, citramalic, citraconic and mesaconic acid or mixtures thereof, more preferably, citric, itaconic, citramalic and citraconic acid or mixtures thereof.
5. A method according to claim 1 , wherein the dicarboxylic acid is selected from maleic, fumaric, and malic acid or mixtures thereof, more preferably, malic acid or mixtures thereof.
6. A method of extracting (meth)acrylic acid from an aqueous reaction medium, the aqueous reaction medium being formed from at least one base catalyst and at least one dicarboxylic acid selected from fumaric, maleic, malic, itaconic, citraconic, mesaconic or citramalic acid or mixtures thereof in aqueous solution and containing the base catalysed decarboxylation products thereof including (meth)acrylic acid or (meth)acrylate base salt, the method comprising the steps of introducing an organic solvent to the aqueous reaction medium for solvent extraction of the (meth)acrylic acid into the organic phase characterised in that the level of base catalyst to the said at least one dicarboxylic acid and/or pre-cursor thereof is maintained at a sub-stoichiometric level in relation to the formation of the first acid salt thereof during the extraction process.
7. A method according to claim 1 , wherein in the case of the (meth)acrylic acid being methacrylic acid, the organic solvent is an external organic solvent with respect to the reaction medium.
8. A method according to claim 1 , wherein the dicarboxylic acid is selected from citramalic or itaconic acid.
9. A process for the production of (meth)acrylic acid comprising the steps of:
forming an aqueous medium of at least one base catalyst and at least one dicarboxylic acid selected from fumaric, maleic, malic, itaconic, citraconic, mesaconic or citramalic acid or mixtures thereof;
decarboxylating the at least one dicarboxylic acid in the presence of the at least one base catalyst under suitable conditions of temperature and pressure to produce (meth)acrylic acid and/or base salts thereof in the aqueous medium;
introducing an organic solvent to the said aqueous medium for solvent extraction of the (meth)acrylic acid into an organic phase;
characterised by the step of adding an additional amount of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the said aqueous medium to enhance the solvent extraction of the (meth)acrylic acid into the organic solvent.
10. A method or process according to claim 1 , wherein the organic solvents for (meth)acrylic acid extraction include hydrocarbon solvents or oxygenated solvents, particularly C 4 -C 20 hydrocarbon solvents.
11. A method or process according to claim 10 , wherein the solvents include toluene, benzene, ethylbenzene, xylene, trimethylbenzene, octane, heptane, hexane, pentane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclohexene, methylcyclohexane, methylethylketone, methyl methacrylate or mixtures thereof; or ionic liquids which are immiscible with water.
12. A method or process according to claim 10 , wherein the mixture of solvents for the extraction of MAA is a C 4 -C 20 hydrocarbon solvent and MMA.
13. A method of extracting (meth)acrylic acid from an aqueous reaction medium into an organic phase in contact therewith, the aqueous reaction medium being formed from at least one base catalyst and at least one dicarboxylic acid selected from fumaric, maleic, malic, itaconic, citraconic, mesaconic or citramalic acid or mixtures thereof in aqueous solution and containing the base catalysed decarboxylation products thereof including (meth)acrylic acid or (meth)acrylate base salt and the organic phase comprises a suitable organic solvent for the said (meth)acrylic acid characterised in that in the aqueous reaction medium the relative level of base catalyst to the said at least one dicarboxylic acid and/or pre-cursor thereof is maintained at a sub-stoichiometric level in relation to the formation of the first acid salt thereof during at least part of the extraction.
14. A method of extracting (meth)acrylic acid from an aqueous reaction medium, the aqueous reaction medium being formed from at least one base catalyst and at least one dicarboxylic acid selected from maleic, fumaric, malic, itaconic, citraconic, mesaconic or citramalic acid or mixtures thereof in aqueous solution and containing the base catalysed decarboxylation products thereof including (meth)acrylic acid and/or (meth)acrylate base salt, the method comprising the step of solvent extraction of the (meth)acrylic acid into an organic phase comprising an organic solvent in contact with the said aqueous reaction medium wherein the method is characterised in that there is added an additional amount of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the said aqueous reaction medium containing the said base catalysed decarboxylation products thereof to enhance the solvent extraction of the (meth)acrylic acid into the organic phase.
15. A method or process according to claim 1 , including the step of separating the organic phase from the aqueous phase after extraction followed by subsequent treatment of the organic phase to isolate the (meth)acrylic acid extracted in the extraction process from the organic solvent.
16. A method or process according to claim 1 , wherein the organic solvent is introduced to the aqueous medium before or after decarboxylation.
17. A method or process according to claim 1 , wherein the sub-stoichiometric level of base is maintained, after, if necessary, being implemented post reaction, during at least that part of the extraction process which is carried out after the decarboxylation step.
18. A method or process according to claim 1 , wherein the sub-stoichiometric level of base is maintained throughout the reaction and extraction.