Patent ID: 8211679
Filing Date: 2012-07-03
Classification: C12P,Y02E

Abstract:
1. A process for producing ethanol comprising: a) contacting a feed gas containing at least one of carbon monoxide or a mixture of carbon dioxide and hydrogen with a microorganism in a bioreactor to metabolize said feed gas and produce an ethanol effluent comprising dilute ethanol having an ethanol concentration of from 1 to 6 wt %; b) separating the ethanol effluent into a broth fraction and a dilute ethanol stream; c) passing the dilute ethanol stream to a stripping column and recovering an ethanol depleted bottoms stream and an overhead vapor stream enriched in ethanol from the stripping column; d) passing at least a portion of the ethanol depleted bottoms stream and at least a portion of the broth fraction to the bioreactor; e) compressing the overhead vapor stream to at least 2 atmospheres to produce a compressed vapor; f) contacting at least a portion of the compressed vapor stream in a first vapor permeation unit with a membrane to produce a retentate having at least 70 wt % ethanol and a first permeate stream; g) returning at least a portion of the first permeate stream to the stripping column; h) contacting the retentate in a second vapor permeation unit with a membrane to produce a dehydrated ethanol stream having at least 99.0 wt % alcohol and a second permeate stream; i) returning at least a portion of the second permeate stream to the stripping column; and, j) recovering at least a portion of the dehydrated ethanol stream as an ethanol product.