Method for separating and recycling acetaldehyde
A technology for separation and recovery of acetaldehyde, applied in the direction of organic chemistry, etc., can solve problems affecting the yield and quality of glyoxal, reducing fluidity, and coloring of products, so as to save energy and auxiliary materials, improve quality, and reduce The effect of production costs
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Embodiment 1
[0022] Example 1 Preheating of liquid to be treated→air stripping
[0023] Place the 500mL three-necked bottle in a constant temperature water bath and install a stirrer. figure 1 for
[0024] Add the solution to be treated (referring to the mixed aqueous solution of acetaldehyde, glyoxal, nitric acid and acetic acid in the process of preparing glyoxal by acetaldehyde nitric acid oxidation) into the three-necked bottle, and when the temperature reaches 30-40°C, start stirring, and at the same time Continuously feed nitrogen into the bottle at a gas flow rate of 15L / min;
[0025] After 2.8 hours, the content of acetaldehyde in the feed liquid decreased from 4.38% to 0.23%, and the main amount of acetaldehyde was discharged with nitrogen, collectively called the mixed gas A1 of nitrogen and acetaldehyde.
Embodiment 2
[0026] Example 2 Preheating of liquid to be treated→air stripping
[0027] The inner diameter of the packed tower is 20mm, the packing height is 800mm, and the packing is a glass silk ring. In the process, the mixed aqueous solution of acetaldehyde, glyoxal, nitric acid and acetic acid) is continuously added from the top of the tower.
[0028] The electric heating belt voltage is 40V, the temperature in the middle of the tower is 40°C, the liquid volume at the top of the tower is 60mL / min, and the gas volume is 15L / min.
[0029] The composition of feed liquid entering the tower is 3.94% of acetaldehyde, 10.06% of glyoxal, 3.55% of nitric acid and 5.83% of acetic acid.
[0030] The feed liquid from the tower kettle consists of 0.27% acetaldehyde, 11.09% glyoxal, 3.50% nitric acid, and 6.46% acetic acid; the main amount of acetaldehyde is discharged with nitrogen, which is collectively called the mixed gas A2 of nitrogen and acetaldehyde.
Embodiment 3
[0031] Example 3 Absorption—Absorb the mixed gas A2 obtained by stripping with a solvent
[0032] The inner diameter of the packed tower is 20mm, the packing height is 1800mm, the packing is glass fiber ring, and the tower is vacuum jacketed.
[0033] The mixed gas A2 of nitrogen and acetaldehyde is continuously fed into the bottom of the tower. The gas is absorbed by primary water spraying, and the flow rate of the absorbed water is controlled by a micro rotor flowmeter. The absorbed water is cooled to below 10°C by the refrigerator, and continuously sprayed into the tower , to obtain dilute acetaldehyde solution B1, the concentration is 5.92%, the acidity of dilute acetaldehyde (calculated as acetic acid, the same below) is 0.09%; the content of acetaldehyde in the exhaust tail gas is 0.08%.
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