Method and device for separation and purification of glycollic acid through rectification and crystallization coupling technology and application
A glycolic acid and crystallization technology, applied in the field of glycolic acid separation and purification, can solve the problems of inability to effectively adjust process parameters, poor glycolic acid separation and purification effect, and complicated production process of glycolic acid, and achieve good separation and purification effect and high work efficiency. , the effect of low cost
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Embodiment 1
[0046] A method for separation and purification of bio-based glycolic acid rectification crystallization coupling technology, the steps are as follows
[0047] Using tungsten / nickel catalyst for one-step hydrothermal conversion of cellulose at 200°C and initial hydrogen pressure of 6MPa to obtain ethylene glycol, and using Pt / AC catalyst for one-step hydrothermal conversion of ethylene glycol at 80°C and initial oxygen pressure of 2MPa Thermal conversion to obtain crude glycolic acid;
[0048] Concentrating the obtained crude glycolic acid by rectification under reduced pressure, wherein the decompression temperature is 50°C, the absolute pressure is 0.5MPa during decompression, and the crude glycolic acid is concentrated to 70wt%;
[0049] The obtained concentrated solution was cooled and crystallized, the cooling rate was 0.5°C / min, the crystallization temperature was -20°C, the stirring speed was 800r / min, and the amount of glycolic acid seed crystals added accounted for 2%...
Embodiment 2-10
[0052] According to the separation and purification method of glycolic acid in Example 1, adjust the temperature and pressure of the vacuum distillation adopted, and all the other parameters are the same, separate and purify glycolic acid, and record the yield and purity of glycolic acid, as shown in Table 1.
[0053] Table 1
[0054] T，℃ P, MPa Yield, % purity,% Example 1 40 0.05 56.7 91.5 Example 2 40 0.1 70.5 93.9 Example 3 40 0.2 81.4 92.7 Example 4 40 0.5 60.6 95.8 Example 5 40 1.0 66.9 96.8 Example 6 30 0.1 59.9 93.4 Example 7 50 0.1 72.3 95.8 Example 8 60 0.1 76.9 96.5 Example 9 70 0.1 78.5 98.7 Example 10 80 0.1 89.4 99.1
Embodiment 11-20
[0056] According to the separation and purification method of glycolic acid in Example 1, adjust the cooling rate, crystallization temperature and rotating speed of the cooling crystallization adopted, and the remaining parameters are the same, separate and purify glycolic acid, and record the yield and purity of glycolic acid, as shown in Table 2 .
[0057] Table 2
[0058] t, °C / min T，℃ R, r / min Yield, % purity,% Example 11 0.5 -5 500 56.8 93.5 Example 12 0.5 -5 500 69.4 96.7 Example 13 0.5 -5 500 68.9 94.9 Example 14 1 -5 500 75.9 95.6 Example 15 1 -5 500 78.4 97.2 Example 16 1 -20 800 84.2 98.3 Example 17 5 -20 800 85.5 96.1 Example 18 5 -20 800 87.3 93.6 Example 19 5 -20 800 89.1 94.7 Example 20 10 -20 800 88.4 95.2
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