Solutions to yellowing of dimethylethanolamine products and high moisture content
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I would like to ask the experts here: The dimethylethanolamine (DMEA) product we produced recently turned dark yellow after a few days. Meanwhile, the moisture level remained around 9 ppm, and it was not possible to reduce it below 5 ppm. I don’t know how to solve this; I earnestly ask for your advice.
I’m sorry, there was a mistake above; it’s not 9 ppm, it’s 900 ppm. The requirement is below 500 ppm
Is there a place where water is leaking in? What process is used? Is distillation employed?
It uses a distillation process. Using EO and dimethylamine as raw materials, the problem of yellowing is quite troublesome; it took a long time to figure out what was causing it. It was originally a pure color, but it turned yellow after a few days. Water should not enter the device; it’s just that this product has very high requirements, demanding an moisture content of less than 0.05%, which is also quite troublesome.
Could you briefly describe what the structure of your distillation tower is like? Intermittent?
Continuous, you know. Is it a distillation issue or a reaction issue?
Is this requirement for solvents used in the electronics and panel industries? Amines tend to yellow over time, which is a normal phenomenon. It is recommended that you store them under nitrogen protection, and avoid using transparent components such as glass tube level gauges that are exposed to light. Water is difficult to remove; it is recommended to use a molecular sieve to remove water before distillation
I have conducted similar experiments on a pilot scale here; the color doesn’t turn yellow, but the product has too high a moisture content, so it never meets the requirements :(
I would like to ask how to prevent discoloration?
Azeotropic, bro! It’s just a dream to expect to achieve 100 ppm moisture levels in electronic-grade reagents