Method for purifying 1,5-pentanediamine and 1,5-pentanediamine
Provided is a method for purifying 1,5-pentanediamine comprising: providing 1,5-pentanediamine to be purified and treating the 1,5-pentanediamine to be purified by a reduction reaction to obtain purified 1,5-pentanediamine. Meanwhile, further provided is 1,5-pentanediamine prepared by the method. The purification method has a concise process and a simple operation, and is suitable for industrial production, and can significantly improve the quality of 1,5-pentanediamine.
1. A method for purifying 1,5-pentanediamine, comprising:
providing a mixture containing 1,5-pentanediamine to be purified and 2,3,4,5-tetrahydropyridine; and
treating said mixture by use of a reduction reaction to reduce said 2,3,4,5-tetrahydropyridine to piperidine thereby obtaining a first purified 1,5-pentanediamine composition,
wherein the reduction reaction comprises an electrochemical reduction or a reduction with use of a reducing agent,
wherein the reducing agent comprises hydrogen gas, (i) the pressure of the hydrogen gas is 0.5 MPa, and the temperature of the reduction reaction is from 100 to 110° C., or (ii) the pressure of the hydrogen gas is 10 MPa, the temperature of the reduction reaction is from 40 to 60° C., and the reduction reaction process comprises:
charging the nickel-based supported catalyst in a stainless steel reactor having an inner diameter of 20 mm and a length of 720 mm, wherein the reactor comprises quartz sands with a particle size of 20 to 40 mesh as a support layer in the lower part of the reactor and a small amount of 20 to 40 mesh quartz sands in the upper part of the reactor to adjust the liquid distribution; and
after the catalyst was activated, mixing the 1,5-pentanediamine to be purified with the hydrogen gas and passing resultant mixture through the catalyst bed from top to bottom.
2. The method according to claim 1 , wherein the content of 2,3,4,5-tetrahydropyridine impurity in the first purified 1,5-pentanediamine composition is less than 0.05 wt %.
3. The method according to claim 1 , wherein the content of 2,3,4,5-tetrahydropyridine impurity in the first purified 1,5-pentanediamine composition is less than 0.03 wt %.
4. The method according to claim 1 , further comprising a distillation step to remove the piperidine from the first purified 1,5-pentanediamine composition to obtain a second purified 1,5-pentanediamine composition, so that the content of piperidine in the second purified 1,5-pentanediamine composition is less than 0.05 wt %, based on the weight of 1,5-pentanediamine in the mixture.
5. The method according to claim 4 , wherein the content of piperidine in the second purified 1,5-pentanediamine composition is less than 0.03 wt %.