Cyclic process for producing taurine

Abstract

There is disclosed a process for producing taurine from ammonium isethionate 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 reacted with ammonium isethionate 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.

Claims

1. A process for producing taurine from alkali taurinate or a mixture of alkali taurinate, alkali ditaurinate, and alkali tritaurinate, comprising: (a) adding ammonium isethionate to a solution of alkali taurinate or a mixture of alkali taurinate, alkali ditaurinate, and alkali tritaurinate to yield alkali isethionate and ammonium taurinate; (b) decomposing ammonium taurinate by heating and removing ammonia to yield taurine; (c) separating taurine by means of solid-liquid separation.

2. The process according to claim 1, wherein a mixture of alkali taurinate, alkali ditaurinate, and alkali tritaurinate is produced by an ammonolysis reaction of alkali isethionate.

3. The process according to claim 1, wherein the alkali metals are lithium, sodium, or potassium.

Description

DESCRIPTION OF THE DRAWING

(1) FIG. 1 illustrates one embodiment of a flowchart for producing taurine from ammonium isethionate.

EXAMPLES

(2) The following examples illustrate the practice of this invention but are not intended to limit its scope.

Example 1

(3) To a 2-L autoclave are added 1200 mL of 24% ammonia solution, 296 g of sodium isethionate, and 2 g of sodium hydroxide. The solution is heated to 260° C. for 2 hours under autogenous pressure. After cooling, 286.2 g of ammonium isethionate is added and ammonia is removed by boiling to bring the pH of the solution to pH 6.5. After heating to remove excess ammonia, concentrating and cooling to room temperature, a suspension of crystalline taurine is obtained. Taurine is recovered by filtration and dried to 189.3 g. Taurine is recovered in a yield of 75.7%.

Example 2

(4) To the mother liquor of Example 1 is added 340 g of gaseous ammonia and total volume is adjusted to 1500 mL with deionized water, followed by addition of 12.4 g of sodium hydroxide. The solution is placed in a 2-L autoclave and is subjected to ammonolysis reaction and treatment with ammonium isethionate as described in Example 1.

(5) Taurine, 241.2 g after drying, is obtained in a yield of 96.2% on the basis of ammonium isethionate used.

Examples 3 to 8

(6) The mother liquor after isolation of taurine, after being saturated with ammonia, is repeatedly subjected to the ammonolysis reaction in the presence of 15 g of sodium hydroxide 5 times for an overall yield of taurine of 96.4% on the basis of ammonium isethionate used.

(7) It will be understood that the foregoing examples, drawing, and explanation are for illustrative purposes only and that various modifications of the present invention will be self-evident to those skilled in the art. Such modifications are to be included within the spirit and purview of this application and the scope of the appended claims.