Cyclic process for producing taurine
There is disclosed a process for producing taurine by the ammonolysis of alkali isethionate in the presence of alkali ditaurinate or alkali tritaurinate, or their mixture, to inhibit the formation of byproducts and to continuously convert the byproducts of the ammonolysis reaction to alkali taurinate. Alkali taurinate is neutralized with isethionic acid to obtain taurine and to regenerate alkali isethionate. The production yield is increased to from 90% to nearly quantitative. The ammonolysis reaction is catalyzed by alkali salts of hydroxide, sulfate, sulfite, phosphate, or carbonate.
1. A cyclic process for producing taurine from alkali isethionate, comprising:
(a) adding one or a combination of two or more catalysts to an ammonia solution of a mixture of alkali isethionate, alkali ditaurinate, and alkali tritaurinate, and subjecting the solution of to ammonolysis reaction to yield a mixture of alkali taurinate, alkali ditaurinate, and alkali tritaurinate;
(b) removing excess ammonia and neutralizing with isethionic acid to obtain a crystalline suspension of taurine in a solution of alkali isethionate, alkali ditaurinate, and alkali tritaurinate;
(c) separating taurine by means of solid-liquid separation; and
(d) returning the mother liquor of (c) to step (a) for further ammonolysis.
2. The process according to claim 1 , wherein one or a combination of two or more catalysts for the ammonolysis reaction is selected from alkali salts of hydroxide, carbonate, sulfate, sulfite, phosphate, nitrate, or carboxylate.
3. The process according to claim 1 , wherein the production yield of taurine is greater than 85%.
4. The process according to claim 1 , wherein the production yield of taurine is greater than 90%.
5. The process according to claim 1 , wherein the production yield of taurine is greater than 95%, to nearly quantitative.
6. The process according to claim 1 , wherein the alkali metals are lithium, sodium, or potassium.