CYCLIC PROCESS FOR PRODUCING ALKALI TAURINATE
There is disclosed a cyclic process for producing alkali taurinate from a solution comprising alkali tritaurinate and isethionate by the ammonolysis in the presence of one or more catalysts. The ammonolysis reaction is catalyzed by alkali salts of hydroxide, sulfate, sulfite, phosphate, or carbonate. Taurine or alkali taurinate is prepared in a yield from 90% to quantitative from alkali isethionate.
1 . A cyclic process for producing alkali taurinate, comprising:
(a) adding an excess of ammonia and at least one catalyst to a solution comprising alkali tritaurinate and alkali isethionate;
(b) subjecting the solution comprising alkali tritaurinate and alkali isethionate to an ammonolysis reaction; and
(c) removing excess ammonia to obtain a solution comprising alkali taurinate.
2 . The cyclic process according to claim 1 , further comprising the steps of:
(d) neutralizing the strongly basic solution comprising alkali taurinate with an acid to form a neutralized solution containing a crystalline suspension of taurine, wherein the neutralized solution has a pH of 5-9;
(e) separating the taurine from the neutralized solution; and
(f) mixing the neutralized solution of step (e) with alkali isethionate and returning the solution to step (a) for further ammonolysis.
3 . The process according to claim 1 , wherein the solution comprising alkali tritaurinate and alkali isethionate is prepared by mixing alkali isethionate and a solution comprising alkali tritaurinate.
4 . The process according to claim 1 , wherein the solution comprising alkali tritaurinate is the neutralized solution after separating taurine in the production of taurine by a prior ammonolysis reaction of alkali isethionate.
5 . The process according to claim 1 , wherein the solution comprising alkali tritaurinate is prepared from triethanolamine.
6 . The process according to claim 1 , wherein the at least one catalyst is selected from the group of alkali salts of hydroxide, carbonate, sulfate, sulfite, phosphate, nitrate, and carboxylate.
7 . The process according to claim 1 , wherein the at least one catalyst is alkali salt of hydroxide.
8 . The process according to claim 1 , wherein the at least one catalyst is sodium hydroxide.
9 . The process according to claim 1 , wherein the at least one catalyst is present in a weight ratio of about 0.01 to about 1.0 compared to the weight of the alkali isethionate.
10 . The process according to claim 1 , wherein alkali tritaurinate is converted to trialkali tritaurinate by adding sufficient amount of alkali hydroxide.
11 . The process according to claim 2 , wherein the acid is selected from hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and organic carboxylic acids.
12 . The process according to claim 2 , wherein the acid is sulfuric acid.
13 . The process according to claim 1 , wherein the yield of taurine from alkali isethionate is from at least 88% to quantitative.
14 . The process according to claim 1 , wherein the alkali is lithium, sodium, or potassium.