Optimizing the efficiency of anhydrous ethanol purification via regenerable molecular sieve

In response to the global energy development trend and greenhouse effects, bio-energy applications are gradually being taken seriously. Gasohol is an alternative fuel that consists of anhydrous ethanol (purity 99.3 wt% or higher) blended with gasoline, which produces less air pollution than standard car fuels. A system was constructed for bio-ethanol production from molasses feedstock. The molasses was fermented and then distilled using a distillation tower, producing up to 90 wt% ethanol concentration. This sample was further concentrated using 3A-type molecular sieves to adsorb water from the ethanol samples until saturated. The sieves were then regenerated for reuse via continuous heating by high-temperature nitrogen. The response surface methodology was applied to determine an optimized operational model for regeneration of molecular sieves. The results indicate that the cost of molecular sieve regeneration (unit energy yield was 0.283 L/kW h) which can stand comparison with other purify methods. The optimal parameters were at a temperature of 193 °C and a heating time of 7 h. 40 min. The results also demonstrated that a yield of 60 L anhydrous ethanol required energy consumption of 212.1 kW h.