For most industrial and fuel uses, the ethanol must be purified. Fractional distillation can concentrate ethanol to 96% volume; the mixture of 96% ethanol and 4% water is an azeotrope with a boiling point of 78.2 °C, and cannot be further purified by distillation. Therefore, 95% ethanol in water is a fairly common solvent. The remaining 5% water must be removed by molecular sieves in either the gas or liquid phase.

Typically in large scale ethanol dehydration, the ethanol is vaporized and cycled with a PSA (Pressure Swing Adsorption) to remove water. Liquid phase molecular sieve dehydration is an effective method for removing moisture. In these types of systems, thermal regeneration is typically employed. The combination of heat, water, hydrocarbon and oxygen makes this a very severe environment for molecular sieves. SEPCOR provides molecular sieve 3A adsorbents that are rugged, of high crush strength, and low reactivity for ethanol dehydration.