Process For Conversion of Biogas to Liquid Fuels

Abstract

Biogases such as natural gas and other gases capable of being biologically derived by digestion of organic matter are converted to a clean-burning hydrocarbon liquid fuel in a process wherein a biogas is fed to a reaction vessel where the biogas contacts a liquid petroleum fraction and a transition metal catalyst immersed in the liquid, vaporized product gas is drawn from a vapor space above the liquid level, condensed, and fed to a product vessel where condensate is separated from uncondensed gas and drawn off as the liquid product fuel. Uncondensed gas can be recycled to the reaction vessel.

1 . A process for producing liquid fuel from a biogas, said method comprising:
 (a) passing said biogas through a liquid petroleum fraction at a temperature of about 80° C. or above but below boiling, while contacting said biogas and said liquid petroleum fraction with a transition metal to produce a gaseous effluent; and   (b) condensing said effluent to liquid form.   
     
     
         2 . The process of  claim 1  wherein said transition metal is a metal with an atomic number from 23 to 79. 
     
     
         3 . The process of  claim 1  wherein said transition metal is a metal with an atomic number from 24 to 74. 
     
     
         4 . The process of  claim 1  wherein step (a) is performed while contacting said biogas and said liquid petroleum fraction with a plurality of transition metals in metallic form. 
     
     
         5 . The process of  claim 4  wherein said transition metals comprise cobalt, nickel, and tungsten. 
     
     
         6 . The process of  claim 4  wherein said transition metals comprise cobalt, nickel, tungsten, and iron. 
     
     
         7 . The process of  claim 1  wherein said liquid petroleum fraction is a member selected from the group consisting of mineral oil, diesel oil, naphtha, kerosene, gas oil, and gasoline. 
     
     
         8 . The process of  claim 1  wherein step (a) is performed at a temperature of from about 100° C. to about 250° C. 
     
     
         9 . The process of  claim 1  wherein step (a) is performed at a pressure of from about 1 atmosphere to about 2 atmospheres. 
     
     
         10 . The process of  claim 1  wherein said biogas is a member selected from the group consisting of hydrogen, carbon monoxide, methane, and mixtures thereof. 
     
     
         11 . The process of  claim 1  wherein said biogas is natural gas. 
     
     
         12 . The process of  claim 1  wherein:
 step (a) comprises feeding biogas to a reaction vessel partially filled with said liquid petroleum fraction to a first externally controlled liquid level to cause said biogas to bubble through said liquid petroleum fraction and through a metallic grid of said transition metal immersed in said liquid; and 
 step (b) comprises performing the following steps continuously and simultaneously with step (a):
 (i) drawing said effluent from a head space in said reaction vessel above said liquid level through a condenser to convert said gaseous reaction product mixture to liquid condensate and uncondensed gas; 
 (ii) passing said liquid condensate and uncondensed gas into a product vessel having a second externally controlled liquid level, to separate said liquid condensate from said uncondensed gas; and 
 (iii) drawing said liquid condensate so separated from said product vessel, as said liquid fuel, while recycling said uncondensed gas from said product vessel to said reaction vessel by directing said uncondensed gas below said first liquid level and through said first metallic grid. 
 
 
     
     
         13 . The process of  claim 12  wherein said metallic grid in said reaction vessel is defined as a first metallic grid, said process further comprising passing said gaseous reaction product mixture through a second metallic grid of at least one transition metal prior to said condenser. 
     
     
         14 . The process of  claim 13  wherein said second metallic grid is external to said reaction vessel and said product vessel. 
     
     
         15 . The process of  claim 12  further comprising passing said uncondensed gas through a fixed bed of inert packing material to recover entrained liquid therein prior to recycling said uncondensed gas to said reaction vessel. 
     
     
         16 . The process of  claim 13  wherein said at least one catalytic transition metal constituting said first metallic grid and said at least one catalytic transition metal constituting said second metallic grid are both pluralities of metals comprising cobalt, nickel, and tungsten. 
     
     
         17 . The process of  claim 1  wherein:
 said a reaction vessel is equipped with a first liquid level control means to define minimum and maximum liquid levels, heating means for heating liquid, an inlet gas distributor, a metallic grid of said transition metal, and a vaporized product outlet port, said inlet gas distributor and said first metallic grid positioned below said minimum liquid level, and said vaporized product outlet port positioned above said maximum liquid level; 
 said condenser is arranged to receive said vaporized product emerging from said vaporized product outlet port; and 
 said product vessel is equipped with a second liquid level control means to define minimum and maximum liquid levels.