Methanol distillation
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Why does an excess of alkali solution result in the product’s acid value exceeding the standard?
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Adding alkali is intended to neutralize certain organic impurities through a reaction, converting them into salts; however, these salts can be acidic, which results in elevated levels of free acid
Too much alkali causes the breakdown of lipids, leading to excessive acidity.
Acidity control depends crucially on the control in the pre-tower, as well as on whether light components are removed completely. Adding alkali is not only intended to adjust the pH but also to prevent equipment corrosion. The recovery of fusel oil from atmospheric pressure columns also has a certain impact on acidity.
If too much alkali is used, theoretically, at the temperature of the pressure reactor, some lipids will hydrolyze, producing acids that lead to an increase in the acid value of the product. However, in practice, I once raised the pH to 12, but the acid value of the pressure tower remained fine. The acid value is poor; it actually has little to do with excessive addition of alkali – it’s caused by inadequate pretreatment in the tower.
What could be the reasons for a high acid value in an atmospheric pressure tower?
What could be the reasons for a high acid value in an atmospheric pressure tower?