Acidity and alkalinity issues with pure methanol
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Should the acidity or alkalinity of pure methanol be controlled? In our plant, the pH value in the pre-treatment tower is kept around 10; methanol is acidic, with a pH value of around 0.000. When methanol becomes alkaline, the pH value is adjusted. I think keeping the pH value too high can cause corrosion to the equipment. Let’s discuss this and hear what Gao Jian has to say
For methanol, a slightly alkaline pH is generally sufficient for optimal prognosis; if the alkalinity level is too high, esters will decompose, producing organic acids, which makes pure methanol acidic. Prognostically, a higher alkalinity of methanol can cause alkaline corrosion of the equipment.
For refined methanol, it is sufficient for the pH level to meet national standards; however, it is best to adjust the pH of the pre-treated methanol to between 7 and 9. This not only facilitates the decomposition of amine compounds in the crude methanol but also prevents acid corrosion.
Because of the non-volatility of basic substances, the alkalinity at the bottom of the pressure tower and the atmospheric pressure tower remains relatively high. It’s better to try to keep it under control!
Our process parameters are set to adjust the pH value of methanol to 7–9, which not only promotes the decomposition of amine compounds in crude methanol but also prevents acid corrosion.
How is the acidity and alkalinity of methanol adjusted? Thank you!