Method for purifying methacrylic acid
View Patent ↗The present invention relates to a process for purifying methacrylic acid, wherein the reaction mixture obtained by a reaction of methacrylamide with water is cooled by mixing with an aqueous medium and then passed into a phase separator. The present invention further describes a system for performing the process according to the invention.
1. A process for purifying methacrylic acid, wherein the reaction mixture obtained by a reaction of methacrylamide with water is cooled when mixing with an aqueous medium and then passed into a phase separator.
2. The process according to claim 1 , wherein the aqueous medium is obtained by separating the reaction mixture obtained in the reaction.
3. The process according to claim 2 , wherein the aqueous medium is discharged from the phase separator.
4. The process according to claim 1 , wherein the aqueous medium has a temperature in a range of 20° C. to 80° C.
5. The process according to claim 1 , wherein the reaction mixture is introduced from a first phase separator into a second phase separator.
6. The process according to claim 5 , wherein discharge of the inorganic phase present in the second phase separator is controlled.
7. The process according to claim 6 , wherein the discharge of the inorganic phase is controlled by a pressure differential measurement and/or a capacitive measurement.
8. The process according to claim 5 , wherein a discharge stream is passed through a screen such that relatively coarse particles are retained.
9. The process according to claim 8 , wherein the relatively coarse particles are mechanically comminuted.
10. The process according to claim 1 , wherein a the volume ratio of the reaction mixture obtained in the reaction relative to aqueous medium is within a range of 2:1 to 1:5.
11. The process according to claim 1 , wherein the reaction is effected at a temperature from 90° C. to 150° C.
12. The process according to claim 1 , wherein the reaction is effected at a pressure of 1.5 bar to 6 bar.
13. The process according to claim 1 , wherein the reaction is carried out in a tubular reactor flowing through from bottom upward.
14. The process according to claim 1 , wherein the reaction is catalyzed with acid.
15. The process according to claim 1 , wherein the reaction mixture comprises at least one stabilizer.
16. The process according to claim 1 , wherein a mixture is employed comprising:
10 to 40% by weight of methacrylamide;
20 to 50% by weight of water;
30 to 65% by weight of sulphuric acid; and
0 to 5% by weight of additional additives.
17. The Process according to claim 1 , wherein the pH of the reaction mixture employed is from 1 to 2.
18. The Process according to claim 1 , wherein residence time is from 10 minutes to 2 hours.
19. The Process according to claim 1 , wherein an organic phase separated from the reaction mixture is purified by a two-stage distillation, comprising a first still and a second still.
20. The Process according to claim 19 , wherein a bottom portion of the second still is evaporated with a circulation evaporator and introduced into the second still.