Chlorine purification towers can use structured packing in the upper separation section to improve vapor-liquid contact and remove less-volatile bromine-containing impurities from purified chlorine. The same separation causes heavy contaminants, including nitrogen trichloride, to become enriched in the descending liquid. Because NCl₃ is an unstable chlorine impurity, the lower tower must be designed around controlled liquid inventory as well as normal mass-transfer performance. Published BASF technology combines upper structured packing with a smaller lower tower section specifically to reduce retained liquid chlorine and NCl₃ inventory. Packing selection should therefore consider reflux distribution, pressure drop, drainage, approved metallurgy and the plant's process-safety basis rather than treating the tower as a conventional chlorine scrubber or ordinary distillation column.

Formaldehyde-water-methanol distillation cannot always be predicted from a conventional structured-packing HETP alone because dissolved formaldehyde participates in reversible liquid-phase reactions. Formaldehyde forms methylene glycol and poly(oxymethylene) glycols with water and hemiformal species with methanol, so the concentration of volatile free formaldehyde changes with temperature and composition. BASF laboratory experiments used 3.5 m of Montz A3-500 structured packing, while pilot-scale studies used 2 m of Sulzer BX wire-gauze packing. These studies showed that equilibrium-stage models using normal packing-efficiency data matched only part of the experimental behavior and that reaction kinetics can need explicit treatment. Formaldehyde packing design should therefore combine validated reactive VLE modeling, real hydraulic data and liquid-distribution analysis rather than treating catalogue HETP as a universal bed-height predictor.

Ammonia recovery from biogas digestate is strongly affected by dissolved CO₂ because carbonate chemistry controls liquid pH and the equilibrium between ammonium and volatile ammonia. Removing part of the CO₂ before the ammonia stripper can raise pH naturally and reduce caustic demand, but excessive CO₂ removal can waste energy and increase ammonia loss. Recent recovery systems therefore combine a CO₂ degasser, structured-packed ammonia stripper and structured-packed ammonia quencher to produce both purified wastewater and concentrated aqueous ammonia. Structured packing is effective only when suspended solids and carbonate precipitation are controlled; dirty digestate may require screening, filtration or a more open contacting technology. Packing selection should therefore follow CO₂ chemistry, pH, solids content, gas composition and recovery targets—not surface area alone.

Crude glycerol from biodiesel production can contain water, methanol, inorganic salts, soaps, fatty material and non-glycerol organic matter. Although vacuum distillation remains a major route to high-purity glycerin, untreated salt-laden feed should not automatically be sent through fine structured packing. Industrial refining schemes commonly separate salts and heavy residue through pretreatment, decantation, filtration or wiped-/thin-film evaporation before using low-pressure-drop packed rectification for the cleaner glycerol separation. Structured packing is valuable because it provides high stage efficiency with limited pressure drop and thermal history, but excessive solids reaching the bed can increase ΔP, raise lower-column temperature and accelerate glycerol degradation. The key design decision is therefore where in the purification train the stream becomes clean enough for structured packing to operate reliably.

Ethylene carbonate purification has an unusual thermal constraint: EC has a high normal boiling point of about 246°C but a melting point near 36.4°C. Vacuum distillation is therefore used to reduce thermal exposure, and structured packing can help by providing efficient separation with low pressure drop and relatively low liquid residence time. However, high-purity battery-grade EC does not necessarily need to be produced entirely by distillation. Published processes use vacuum rectification to obtain approximately 99.5–99.8% EC and then employ controlled crystallization and sweating to exceed 99.99% while removing glycol, halogenated-alcohol and oligomer impurities. Structured packing should therefore be optimized to deliver the correct crystallizer feed quality—not automatically to chase the final product purity by adding more stages and reflux.