Patent ID: 8211692

Claim:
A process for converting a feed gas comprising a mixture of at least one of CO or a mixture of CO 2 and H 2 under anaerobic conditions using a bioreactor containing microorganisms to produce a liquid product wherein a liquid permeable membrane partitions the microorganisms from a liquid phase, retains the microorganisms in direct contact with the gas phase to produce the liquid product and delivers the liquid product to a liquid phase on the side of the substrate opposite the gas phase and the anaerobic conditions include the feed gas having an oxygen concentration of less than 1000 ppm and the liquid phase having a redox potential in the range of less than −200 mV, said process comprising: a) passing the feed gas to a gaseous phase for contact with a gas contacting side of a membrane that retains microorganisms in a plurality of bio-pores defined by a biolayer and having effective diameters of at least 1 μm over at least a portion of the pore length for retaining the microorganisms therein as the biolayer and a porous surface on the gas contacting side that presents open ends of the bio-pores to the feed gas; b) passing a liquid phase over a liquid contacting side of the substrate comprising a hydration layer that controls the flow of product containing liquid from bio-layer; c) maintaining sufficient positive pressure on the gas contacting side relative to the liquid contacting side to establish a first differential pressure such that there is a higher pressure on the gas contacting side than the liquid contacting side to transport the feed gas and the liquid products in co-directional flow from the gas contacting side to the liquid contacting side for a limited period of time; and, d) periodically subjecting the bio-layer to a laving cycle by reducing the first differential pressure such that liquid from the liquid contacting side laves into the biolayer, the laved liquid remains within the biopores during the laving cycle and the pressure on the liquid contacting side does not exceed the pressure on the gas contacting side.