pH value of methanol distillation – in confusion
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Some time ago, we encountered a problem: the acid value measured in our methanol distillation unit was high. So we reduced the amount of alkali added, and the acid value dropped… I’m confused – why? Don’t addition and subtraction reduce the acid value? I humbly ask Master Hai for his guidance
The analysis might be incorrect; moreover, the analysis reflects the instantaneous process conditions
Has there been no change in the feed entering the methanol distillation tower? Has the acidity of the feed entering the tower decreased?
I personally think that too much alkali will cause a saponification reaction in the pressure tower. Adding alkali is primarily intended to neutralize the acidic components in crude methanol; if too much is added, methyl formate and ethyl formate will undergo saponification reactions under alkaline conditions in the pressure tower, resulting in the release of formic acid and an increase in acidity.
Agree with the view above; methyl formate compounds hydrolyze to produce acids in alkaline environments, with a typical pH range of 8–9
Commonly known as anti-alkali; when the alkaline solution is exposed to high temperatures, it reacts with something I can’t remember, resulting in acidic substances – this happens when there is too much alkali
Ask the person who made this decision and you’ll get an answer – why it’s necessary to reduce the amount of alkali added when the acidity level is high; you already have the answer
I really didn’t know that before; I only knew that adding too much alkali would increase the acid value. It’s all based on experience. So, it turns out that methyl formate is this kind of substance~