P=1 013 bar
Reactive distillation lines with one feed
The highest boiling point in the system is that of acetic acid, while the lowest boiling point is displayed by the MeOH-MeAc azeotrope (Fig. 2.4). The RD line diagram makes it possible to determine the product regions of RD for infinite reflux. Analogously to conventional distillation, the top and bottom products have to lie on an RD line and on the balance line. It can be seen that the desired products, namely MeAc and water, do not lie in the product region.
But by analogy with extractive distillation, it can be expected that a second feed point would drastically widen the product region at a finite reflux ratio and thus also increase the conversion. Between the two feed points, the column profile is perpendicular to the distillation lines (Fig. 2.5). Since this effect is based on the finite nature of the reflux ratio employed, we can expect product purity and conversion to first increase with an increase in the reflux ratio and then slowly decrease again. The limiting value that is established for an infinite reflux ratio is determined by the azeotrope concentration in the methyl acetate/methanol system.
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