Patent ID: 7923227

Claim:
A process for converting a feed gas containing at least one of CO or a mixture of CO2 and H2 to a liquid product under anaerobic conditions and delivering the liquid product to a fermentation liquid, said process comprising: a) passing a feed gas into gas phase contact with a biofilm comprising immobilized microorganisms that produce liquid products from the feed gas; b) retaining the biofilm on a biofilm exclusion surface of a gas contacting side of a hydrophilic membrane wherein the biofilm exclusion surface is the outer surface of the gas contacting side and the biofilm exclusion surface inhibiting penetration of the biofilm into pores; b) passing a fermentation liquid comprising water and nutrients across a porous surface of a liquid contacting side of the membrane; c) permeating fermentation liquid from the liquid contacting side through the membrane and into contact with the biofilm; d) flowing fermentation liquid containing liquid products from the biofilm through the membrane and to the liquid contacting side of the membrane; (e) collecting fermentation liquid containing liquid products from the liquid contacting side of the membrane to recover liquid products from the process; wherein the feed gas is synthesis gas having an oxygen concentration of less than 1000 ppm, the liquid supply chamber retains a liquid having a redox potential in the range of less than −200 mV, the biofilm comprises microorganisms that produce ethanol and a liquid recovery chamber retains an ethanol containing liquid; and, wherein the feed gas passes serially through multiple assemblies of hollow fiber membranes, at least one feed gas chamber supplies feed gas for each hollow fiber membrane assembly and CO2 is removed from the gas as it passes between assemblies through the system.