Preparation method of 3-mercaptopropionic acid

A preparation method of 3-mercaptopropionic acid, wherein the preparation method consists of the following steps:

• (1) Sulfuration:
• mixing sodium acrylate with sodium hydrosulfide, dissolving the mixture with water, and reacting;
• (2) Decomposition:
• adding sodium sulfide and sulfur powder and further reacting;
• (3) Acidification:
• after completion of the above reactions, cooling, crystallizing, and acidifying with an acid to obtain a solution of 3-mercaptopropionic acid;
• and
• (4) Extracting the obtained solution of 3-mercaptopropionic acid, and then distilling under reduced pressure to obtain 3-mercaptopropionic acid;
• wherein, the sodium acrylate has a mass percentage of sodium acrylate of >99%;
• the sodium hydrosulfide has a mass percentage of sodium hydrosulfide of 70%;
• the sodium sulfide has a mass percentage of sodium sulfide of 60%;
• and the sulfur powder has a mass percentage of sulfur powder of 99%;
• wherein
• in Step (1), the reaction temperature is in the range of 40-80° C.;
• the reaction pressure is in the range of 0.01-1.5 MPa;
• and the reaction time is in the range of 0.5-20 h;
• in Step (2), the reaction temperature of the decomposition reaction is in the range of 100-150° C.;
• the reaction pressure of the decomposition reaction is in the range of 0.01-1.5 MPa;
• and the reaction time of the decomposition reaction is in the range of 0.5-20 h;
• in Step (3), when acidifying with the acid, the acidifying temperature is in the range of 0-100° C., and the acidifying time is in the range of 0.5-5 h;
• in Step (1), a molar ratio of the sodium hydrosulfide to the sodium acrylate is in the range of 0.1-10:1;
• in Step (2), a molar ratio of the sodium sulfide to the sodium acrylate is in the range of 0.1-10:1;
• in Step (2), a molar ratio of the sulfur powder to the sodium acrylate is in the range of 0.01-1:1;
• and
• in Step (3), a molar ratio of the acid to the sodium acrylate is in the range of 0.1-5:1.