About a strange distillation
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In conventional packed tower distillation, those with higher boiling points should always be located at the bottom of the tower, while those with lower boiling points are at the top. The more thorough the reflux, the higher the efficiency of the tower, and the higher the proportion of light components at the top of the tower. There is a strange phenomenon at present: when an aqueous solution of propionoxime at 20% concentration is fed into the tower at a boiling point of 100 degrees, with 4m BX500 packing used in both the stripping section and the rectification section, the propionoxime content in the overhead distillate is around 29%. A reflux ratio of 1:1 can increase the propionoxime concentration in the overhead distillate to 40%, but increasing the reflux further does not raise the overhead concentration any more. Propanethioxime has a boiling point of 136 degrees and a melting point of 60 degrees; it sublimes easily and is considered a high-molecular-weight component ； The boiling point of water is 100 degrees; it is a light component. Have you come across similar distillation processes?
Has an azeotrope formed? It is recommended to clarify the physical properties first.
The reconstituted fraction should be at the bottom of the tower. It’s estimated that there is water inside, causing vapor distillation.
It seems an azeotrope has formed; consider trying to avoid the azeotrope temperature
The physical properties of the material are very important; it is necessary to understand them in order to carry out distillation or make improvements and optimizations
1. Check if it is azeotropic with water. 2. Is the tower at atmospheric pressure? The saturated vapor pressure curves of substances vary under different pressures, with both the heavy components and the light components being defined relative to a certain pressure.
The azeotrope temperature is generally much lower than their respective boiling points, but the top temperature of the tower is currently around 98 degrees. Additionally, in azeotropic distillation, the composition at the top of the column should not change with the reflux ratio. I don’t understand vapor distillation; could someone give a brief explanation?
What is the composition at the bottom of the tower? Can a sample be taken for analysis?
At the bottom of the tower, there is still propyl oxime and water; the content of propyl oxime is generally around 6%, and the temperature at the bottom of the tower remains steady at 100–101 degrees
I checked online and it seems that propionoxime is azeotropic with water