Formic acid binary azeotropes

Methyl Vinyl Ketone. Methyl vinyl ketone [78-94-4] (3-buten-2-one) is a colorless Hquid with a pungent odor. It is stable only below 0°C, and readily polymerizes on standing at room temperature. It can be inhibited for storage and transportation by a mixture of acetic or formic acid and hydroquinone or catechol (266). This ketone is completely soluble in water, and forms a binary azeotrope with water (85 MVK 15 H2O vol %) at 75.8°C. 

Formic acid can be dehydrated with propyl formate as entrainer. Small contents of formic acid and water in acetic acid can be entrained away with chloroform which forms binary azeotropes with water and formic acid but no other azeotropes in this system. 

The next mixture contains formic acid (11.9 %), acetic acid (31.4%) and water (56.7%). The difference of freezing points of water and acids is too close (9 and 16 °C respectively), so that the separation by crystallisation is not feasible. If distillation is applied, one can separate two binary mixtures, formic acid/water and acetic acid/water. The separation of these mixtures is known, and it can be solved by standard techniques. Figure 7.23 shows the final sequencing that will consists from a flash, a distillation column, and a special device of extractive azeotropic distillation. 

Diagram of the four distillation areas of the ternary system water-formic acid-acetic acid, having a binary and a ternary azeotrope, and position of composition R [39]... 

As shown in Figure 8.44, the predicted ternary phase equihbria at 1 atm show three homogeneous azeotropes. T vo are binary (water/formic acid and water/acetic acid) and... 

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