Integrated process for filtering constituents from a gas stream

Abstract

The invention provides a process for producing a fermentable gas stream from a gas source that contains one or more constituent which may be harmful to the fermentation process. To produce the fermentable gas stream, the gas stream is passed through a specifically ordered series of removal modules. The removal modules remove and/or convert various constituents found in the gas stream which may have harmful effects on downstream removal modules and/or inhibitory effects on downstream gas fermenting microorganisms. At least a portion of the fermentable gas stream is preferably capable of being passed to a bioreactor, which contains gas fermenting microorganisms, without inhibiting the fermentation process.

1 . A process for removing constituents from an input gas stream, comprising removing, from the input gas stream, particulates, tar, and or at least one component comprising chloride, dimethyl ether, and or acetaldehyde from the input gas stream, contacting the input gas stream with a catalyst to produce a fermentable gas stream, wherein the fermentable gas stream comprises less than 100 ppm oxygen, less than 1 ppm acetylene, and less than 1 ppm hydrogen cyanide, and wherein the catalyst comprises reduced metal copper supported on alumina, silica, titania, ceria, lanthana, carbon, silica-alumina, or zeolites. 
     
     
         2 . The process of  claim 1 , further comprising passing at least a portion of the fermentable gas stream to a bioreactor, wherein the bioreactor contains a culture comprising a fermentation broth and one or more microorganisms. 
     
     
         3 . The process of  claim 2  wherein at least one microorganism is a carboxydotrophic bacterium. 
     
     
         4 . The process of  claim 3  wherein the carboxydotrophic bacterium may be selected from  Moorella, Clostridium, Ruminococcus, Acetobacterium, Eubacterium, Butyribacterium, Oxobacter, Methanosarcina, Desulfotomaculum , or any combination thereof. 
     
     
         5 . The process of  claim 1  wherein the microorganism is  Clostridium autoethanogenum.    
     
     
         6 . The process of  claim 1 , wherein at least a portion of the input gas stream is a synthesis gas and/or a producer gas. 
     
     
         7 . The process of  claim 1 , wherein the process further comprises measuring the level of constituents in the input gas stream and/or the fermentable gas stream. 
     
     
         8 . The process of  claim 1 , wherein the input gas stream comprises CO, CO 2 , H 2 , or any combination thereof. 
     
     
         9 . The process of  claim 1 , wherein the input gas stream comprises oxygen up to 7000 ppm, acetylene up to 700 ppm, and hydrogen cyanide up to 60 ppm. 
     
     
         10 . The process of  claim 1 , wherein the input gas stream comprises oxygen up to 10000 ppm, acetylene up to 1500 ppm, and hydrogen cyanide up to 500 ppm. 
     
     
         11 . The process of  claim 1 , wherein the input gas stream comprises carbon monoxide and the process consumes less than 10 percent of the carbon monoxide in the input gas stream. 
     
     
         12 . The process of  claim 1 , wherein the process is carried out at a pressure of at least 138 kPag, or at least 345 kPag, or at least 690 kPag. 
     
     
         13 . The process of  claim 1 , wherein the catalyst is copper (I) or sulfided copper (I) supported on alumina. 
     
     
         14 . The process of  claim 1 , wherein the catalyst is copper (II) or sulfided copper (II) supported on alumina. 
     
     
         15 . The process of  claim 1  wherein the catalyst was reduced in an environment of about 1 volume % hydrogen in nitrogen at about 120° C. 
     
     
         16 . The process of  claim 1  wherein the input gas stream comprises mercury, the fermentable gas stream comprises less mercury than the input gas stream, and the copper is sulfided. 
     
     
         17 . The process of  claim 2  further comprising, removing from the bioreactor, a product stream and a post-fermentation gaseous substrate and wherein at least a portion of the input gas comprises at least portion of the post-fermentation gaseous substrate. 
     
     
         18 . The process of  claim 2  wherein gas fermentation in the bioreactor produces a product selected from ethanol, acetate, butanol, butyrate, 2,3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate, isoprene, fatty acids, 2-butanol, 1,2-propanediol, 1-propanol, chorismate-derived products, 3-hydroxybutyrate, or 1,3-butanediol. 
     
     
         19 . The process of  claim 18  wherein the product is separated from the culture using a technique selected from fractional distillation, vacuum distillation, evaporation, pervaporation, gas stripping, phase separation, or liquid-liquid extraction. 
     
     
         20 . The process of  claim 1  wherein the process is operated in a continuous mode.