Process for producing taurine
There is disclosed a process for producing taurine in a molar yield of at least 80% from alkali isethionate, alkali ditaurinate, or alkali tritaurinate by adding excess ammonia and at least of equal molar amount of an alkali hydroxide to a solution comprised of alkali ditaurinate, alkali tritaurinate, or their mixture and subjecting the solution to an ammonolysis to yield a solution comprised of alkali taurinate.
1. A process for producing taurine in a molar yield of at least 80% on the basis of alkali isethionate in more than one vessel, comprising:
(a) adding alkali hydroxide and excess ammonia to a solution comprised of alkali isethionate and alkali ditaurinate; wherein the molar amount of alkali hydroxide is at least equal to the molar amount of total taurinates comprising alkali ditaurinate in the solution; and wherein the alkali is lithium, sodium, potassium, or a mixture thereof;
(b) subjecting the solution of step (a) to an ammonolysis;
(c) removing excess ammonia from the solution of step (b) to obtain a solution comprising alkali taurinate; and
(d) converting the alkali taurinate of step (c) to taurine.
2. The process according to claim 1 , wherein the solution comprised of alkali isethionate and alkali ditaurinate is comprised of the mother liquor solution produced from alkali isethionate in a process comprising the steps of:
(1) adding excess ammonia to a solution comprised of alkali isethionate; wherein the alkali is lithium, sodium, potassium, or a mixture thereof;
(2) subjecting the solution of step (1) to an ammonolysis;
(3) removing excess ammonia from the solution of step (2) to obtain a solution comprising alkali taurinate;
(4) converting the alkali taurinate of step (3) to taurine; and
(5) isolating the taurine of step (4) to form a mother liquor solution.
3. The process according to claim 2 , wherein the mother liquor solution is comprised of alkali ditaurinate, alkali isethionate, and alkali tritaurinate.
4. The process according to claim 2 , wherein the mother liquor solution is comprised of alkali isethionate and alkali ditaurinate.
5. The process according to claim 1 , wherein the alkali taurinate is converted to taurine by reacting with an acid.
6. The process according to claim 5 , wherein the acid is selected from the group consisting of sulfuric acid, hydrochloric acid, hydrobromic acid, nitric acid, phosphoric acid, and organic carboxylic acid.
7. The process according to claim 1 , wherein the alkali taurinate is converted to taurine by reacting with an ion exchange resin.
8. The process according to claim 1 , wherein the alkali hydroxide is added to the solution comprised of alkali isethionate and alkali ditaurinate to a pH of at least 10.
9. The process according to claim 1 , wherein the excess ammonia is recovered for reuse.
10. The process according to claim 1 , wherein the alkali hydroxide is added to the solution comprised of alkali isethionate and alkali ditaurinate to a pH of at least 9.
11. The process according to claim 2 , wherein the mother liquor solution is comprised of alkali ditaurinate.
12. The process according to claim 2 , wherein the mother liquor solution is comprised of alkali tritaurinate.
13. The process according to claim 2 , wherein the mother liquor solution is comprised of unreacted alkali isethionate.
14. The process according to claim 1 , wherein the solution comprised of alkali isethionate and alkali ditaurinate is the mother liquor solution produced from alkali isethionate in a process comprising the steps of:
(1) adding excess ammonia to a solution comprised of alkali isethionate; wherein the alkali is lithium, sodium, potassium, or a mixture thereof;
(2) subjecting the solution of step (1) to an ammonolysis;
(3) removing excess ammonia from the solution of step (2) to obtain a solution comprising alkali taurinate;
(4) converting the alkali taurinate of step (3) to taurine; and
(5) isolating the taurine of step (4) to form a mother liquor solution.
15. The process according to claim 14 , wherein the mother liquor solution is comprised of unreacted alkali isethionate.
16. The process according to claim 14 , wherein the mother liquor solution is comprised of alkali ditaurinate.
17. The process according to claim 14 , wherein the mother liquor solution is comprised of alkali isethionate and alkali ditaurinate.
18. The process according to claim 14 , wherein the mother liquor solution is comprised of alkali tritaurinate.
19. The process according to claim 1 , wherein the taurinates are selected from the group consisting of taurine, sodium ditaurinate, sodium tritaurinate, and a mixture thereof.