Acetic acid dehydration tower: How to consider the issue of azeotrope hydrolysis in actual operations?
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For the dehydration of acetic acid, esters (such as isopropyl acetate and n-butyl acetate) are generally used as heterogeneous azeotrope formers; in practice, it seems that the esters hydrolyze into alcohols. Normally, esters and water are immiscible at the top of the tower, allowing phase separation to ensure stable operation of the tower; however, the alcohols produced cause esters and water to become miscible, preventing phase separation. Is this process equivalent to reactive distillation taking place in a dehydration tower? However, when using Aspen for simulation, equilibrium constants cannot be applied (they are too large, resulting in an excessive amount of alcohol, which is not realistic). But this isn’t a catalytic reaction either – there is no kinetics at all. How should this be handled? Thank you all! !
Can we try to control the pH and temperature of the system? Reduce the hydrolysis of esters under alkaline conditions.
:Lol, is ester always used for the dehydration of industrial acetic acid? I thought toluene was being used. . . . .
:Well, in that case you can only lower the temperature of the system by using vacuum; there’s no other solution. I’m not sure what the separation efficiency will be under vacuum conditions
Well, n-butyl acetate and n-propyl acetate are commonly used in the PTA industry； Isopropyl acetate is widely used in the PVA industry. I’m not sure whether toluene is acceptable in terms of safety and toxicity considerations