Membrane Technology & Research

Ethanol Dehydration

Ethanol forms an azeotrope with water at 95 wt% ethanol and 5 wt% water. As a consequence, simple distillation can easily dehydrate wet ethanol to about 90% ethanol. However, removing the remaining water requires another technique, most commonly extractive distillation with an entrainer or molecular siev based temperature and pressure swing adsorption. These processes are complex and energy intensive. Membrane vapor permeation with robust zeolitic membranes is a simple, low cost and compact alternative.

Plant Membrane Area  (m2)

Feed Flow Rate (gallons/day)

Water Removal Needed  




8 → 0.5



10→ 0.4



10→ 0.5

Photographs of compact zeolite membrane plants processing 1,000 to 3,000 gallons per day of wet ethanol.


Membrane Technology and Research, Inc. 39630 Eureka Drive, Newark, CA 94560 • (650) 328-2228