Acetonitrile recovery often involves much more than removing water. Industrial crude ACN may contain HCN, acrylonitrile and other organics, while ACN and water form a pressure-sensitive minimum-boiling azeotrope. Modern recovery processes can use water-assisted impurity removal, pressure-swing distillation and intermediate side-draw product recovery, with structured packing used in multiple columns to provide high stage density and low pressure drop. Packing selection should be based on the exact feed source, pressure level, internal reflux, impurity targets and product withdrawal location rather than ACN purity alone.

Formic acid and water form a maximum-boiling azeotrope containing about 77.6 wt% formic acid at atmospheric pressure, so conventional single-pressure distillation cannot directly produce essentially anhydrous formic acid simply by adding more packing. Industrial purification may use pressure-swing, extraction, amine-based separation or other processes before final vacuum purification. Structured packing becomes especially valuable in deep-vacuum sections because low pressure drop preserves low bottom pressure, while highly corrosive service may require fluoropolymer packing and specialty vessel materials. A recent CO₂-to-formic-acid process used a Zr702 purification column with PTFE structured packing at about 35 mbar.

Phthalic anhydride purification removes lower-boiling impurities such as maleic anhydride and benzoic-acid-related components and separates PA from higher-boiling compounds such as phthalide and heavy residues. Industrial PA purification has used structured packing under vacuum, where low pressure drop helps reduce required boiling temperature. The application is unusual because PA melts at about 131°C, so liquid distribution, drainage, insulation and avoidance of cold spots are critical to prevent crystallization inside packing and other tower internals. Packing selection should therefore balance stage efficiency, vacuum pressure drop, heavy-end tolerance and temperature uniformity rather than HETP alone.

Dimethyl carbonate and methanol form an azeotropic system that limits conventional distillation, so industrial DMC purification commonly requires extractive distillation or another azeotrope-breaking process. Structured packing has been directly applied in DMC water-removal, extractive and final rectification columns because it provides high separation efficiency with relatively low pressure drop. Packing selection should account for extractant circulation, water removal, methanol recycle, DMC recovery, liquid distribution and the hydraulic trade-off between high surface area and solvent-loaded capacity.

Structured packing can be used in epichlorohydrin purification columns to separate water and light impurities from ECH while rejecting dichlorohydrins and heavier components. A high-purity design can withdraw finished ECH as a liquid side stream rather than directly from the overhead, allowing water and lighter impurities to continue concentrating above the product withdrawal point. Low-pressure-drop structured packing also supports vacuum operation and lower tower temperatures. Packing grade, side-draw elevation, collectors, redistribution and corrosion-resistant materials should therefore be designed as one complete purification system.