Separation of the methanol, formaldehyde, and water tricomponent system
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Methanol contains 20% formaldehyde and 10% water. Is there any way to remove the water, without having to separate methanol and formaldehyde?
If conditions permit, increase the processing capacity of the water separation tower. However, I’m not sure if you only want to separate methanol, formaldehyde, and water; in that case, distillation can be used based on their different relative volatilities to achieve separation
Only 10% of the water cannot be completely separated through ordinary distillation; you can add a dehydrating agent so that methanol, water, and the dehydrating agent can utilize the principle of triple azeotropy to remove the water.
Distillation is generally used. However, the three may form an azeotrope.
Upon inquiry, the normal boiling point of water is 100 degrees, that of methanol is 78.25 degrees, and that of formaldehyde is 10.55 degrees. It can be seen that distillation can be used to obtain high-purity methanol and formaldehyde at the top of the tower, while water is obtained at the bottom; separation should not be difficult
Based on their different boiling points, methanol and formaldehyde have lower boiling points than water; by controlling the temperature properly, separation is not difficult
The three will form an azeotrope, and an azeotrope-forming agent must be added for dehydration. Lipid azeotropes can be considered
Do we need to add an azeotrope? If necessary, which specific azeotrope should be added?
1. Direct distillation is also an option, but it results in a large amount of distillate at the top of the tower, leading to higher energy consumption； 2. Best solution (I carried out a similar project in 2004, but without formaldehyde): Use an azeotropic distillation approach, with a water scavenger to remove water from the top of the tower. Pure benzene and water are azeotropic, so a choice can be made. 3. There is formaldehyde here; I’m not sure if the methods mentioned above will work. 4. Desiccants can also be used to absorb moisture: they require less energy, but they can easily contaminate the material. Calcium chloride can be used as a desiccant.