Integrated processes for anaerobic conversion of hydrogen and carbon oxides to alcohol

A continuous process for the anaerobic bioconversion of a gas substrate comprising carbon monoxide, hydrogen and carbon dioxide in an aqueous menstruum containing microorganisms suitable for converting said substrate to an alcohol that comprises:

• a. steam reforming hydrocarbonaceous feedstock to provide a syngas having an electron to carbon ratio greater than about 7:1, said steam reforming being performed in a steam reformer having at least one gas reforming section and at least one hotbox section;
• b. continuously introducing into a bioreactor assembly, said syngas and biogas, said biogas comprising at least about 20 or 25 mole percent carbon dioxide and at least about 40 mole percent methane, said biogas having an electron to carbon ratio not greater than about 0.1:1 to provide an overall gas substrate having an electron to carbon ratio in the range of about 5.2:1 to 6.8:1;
• c. continuously contacting said syngas and said biogas with said aqueous menstruum to bioconvert substrate gas to alcohol and providing an alcohol-containing menstruum and a substrate depleted gas phase, said contacting being in a bioreactor assembly containing said menstruum;
• d. continuously withdrawing substrate depleted gas phase from said aqueous menstruum, said depleted gas phase having a lower mole ratio of carbon dioxide to methane than that of the overall gas substrate;
• e. passing at least a portion of the depleted gas phase to the steam reformer of step (a);
• and
• f. continuously or intermittently withdrawing a portion of said menstruum for recovery of said alcohol, said withdrawal being sufficient to maintain the alcohol in said menstruum below a concentration that unduly adversely affects the microorganisms.

A continuous process for the anaerobic bioconversion of a gas substrate comprising carbon monoxide, hydrogen and carbon dioxide in an aqueous menstruum containing microorganisms suitable for converting said substrate to an alcohol, the process comprising:

• a. continuously introducing into a bioreactor assembly containing aqueous menstruum a gas substrate having an electron to carbon ratio greater than about 5.2:1;
• b. continuously contacting said syngas with said aqueous menstruum to bioconvert gas substrate to alcohol and providing an alcohol-containing menstruum and a substrate depleted gas phase;
• c. continuously withdrawing substrate depleted gas phase from said aqueous menstruum;
• d. passing at least an aliquot portion of the substrate depleted gas phase to the hot box section of the steam reformer;
• and
• e. continuously or intermittently withdrawing a portion of said menstruum for recovery of said alcohol, said withdrawal being sufficient to maintain the alcohol in said menstruum below a concentration that unduly adversely affects the microorganisms.

In a continuous process for the anaerobic bioconversion of a gas substrate comprising carbon monoxide, hydrogen and carbon dioxide in an aqueous menstruum containing microorganisms suitable for converting said substrate to alcohol comprising continuously introducing said gas substrate into a bioreactor assembly containing said aqueous menstruum to bioconvert gas substrate to alcohol and providing an alcohol-containing menstruum and a depleted gas phase;

• continuously withdrawing depleted gas phase from said aqueous menstruum;
• continuously or intermittently withdrawing a portion of said menstruum for recovery of said alcohol, said withdrawal being sufficient to maintain the alcohol in said menstruum below a concentration that unduly adversely affects the microorganisms, wherein:
• a. the gas substrate as introduced into the bioreactor assembly has a ratio of electrons to carbon atoms in the range of about 5.2:1 to 6.8:1;
• b. the bioreactor assembly comprises at least two bioreactor stages in gas flow sequence wherein at least the last bioreactor stage in gas flow sequence is characterized as having a substantially uniform aqueous menstruum and a substantially non-uniform composition of the gas bubbles between the inlet portion and the outlet portion;
• and
• c. a carbon monoxide-containing gas having a ratio of electrons to carbon atoms less than about 6.5:1 is introduced into the last bioreactor stage in an amount sufficient to provide a ratio of electrons to carbon atoms in the admixed gases in the range of about 5.2:1 to 7.5:1.

An integrated process for making alcohol from a combined gas substrate of 1) CO2 rich gas form an anaerobic fermentation of carbohydrates and 2) a syngas gas substrate comprising carbon monoxide, hydrogen and carbon dioxide, the process comprising:

• a. a carbohydrate to alcohol process comprising:
• i. bioconverting under fermentation conditions including the presence of biocatalyst a carbohydrate-containing aqueous broth to provide an alcohol-containing broth which broth contains biocatalyst and carbon dioxide gas;
• ii. removing carbon dioxide gas from the alcohol-containing broth;
• iii. separating by distillation alcohol from said alcohol-containing broth and providing a whole stillage containing water, unconverted carbohydrates and biocatalyst;
• iv. separating the whole stillage by centrifugation to provide a thin stillage and distillers grains;
• v. evaporating water from the thin stillage to provide a concentrate containing unconverted carbohydrates, and
• b. a syngas to alcohol process comprising:
• i. continuously introducing said gas substrate into a bioreactor assembly containing said aqueous menstruum to bioconvert gas substrate to alcohol and providing an alcohol-containing menstruum and a depleted gas phase;
• ii. continuously withdrawing depleted gas phase from said aqueous menstruum;
• iii. continuously or intermittently withdrawing a portion of said menstruum for recovery of said alcohol,
• iv. separating the withdrawn portion of said menstruum by distillation to provide alcohol and an aqueous stillage,
• wherein at least a portion of the separated carbon dioxide from step (a)(ii) is used as a portion of the gas substrate in step (b)(i) to provide a gas substrate having an electron to carbon atom ratio of between about 5.2:1 and 6.8:1.

A continuous, integrated process for the anaerobic bioconversion of a gas substrate comprising carbon monoxide, hydrogen and carbon dioxide in an aqueous menstruum containing microorganisms suitable for converting said substrate to alcohol that comprise:

• a. continuously reforming hydrocarbonaceous feedstock at elevated temperature and pressure to provide a syngas containing hydrogen, carbon monoxide, carbon dioxide and water vapor, said reforming comprising heat exchange between the syngas and the hydrocarbonaceous feedstock;
• b. continuously generating steam from the syngas to provide a first cooled syngas, said first cooled syngas saturated with water vapor;
• c. continuously passing the first cooled syngas to a distillation reboiler to provide a second cooled syngas having a temperature of 100° C. and 110° C. degrees;
• d. continuously contacting said second cooled syngas with said aqueous menstruum to bioconvert gas substrate to alcohol and providing an alcohol-containing menstruum and a syngas depleted gas phase;
• e. continuously withdrawing substrate depleted gas phase from said aqueous menstruum;
• f. continuously or intermittently withdrawing a portion of said menstruum for recovery of said alcohol, said withdrawal being sufficient to maintain the alcohol in said menstruum below a concentration that unduly adversely affects the microorganisms;
• and
• g. continuously recovering alcohol from said withdrawn menstruum in a distillation column, said distillation column using heat provided by step (c)

A continuous process for the production of alcohol from a combination of renewable and non-renewable gas streams the process comprising:

• a.) combining a non-renewable gas with a renewable gas to produce a combined substrate comprising hydrogen, carbon monoxide, and carbon dioxide in which between about 20 to 70 percent of the carbon is from renewable carbon, the balance of the gas stream is made from non-renewable carbon, and the e/C ratio is in a range from 5.5:1 to 6.4:1.
• b.) contacting the substrate with a menstruum containing a biocatalyst in the form of microorganisms in an anaerobic fermentation zone and obtaining at least 85 mole percent conversion of the hydrogen, carbon monoxide, and carbon dioxide of the substrate;
• c.) continuously withdrawing a depleted gas phase from said aqueous menstruum;
• d.) continuously or intermittently withdrawing a portion of the menstruum from the fermentation zone and recovering an alcohol product from the fermentation zone.

A continuous process for the anaerobic bioconversion of a gas substrate comprising carbon monoxide, hydrogen, and carbon dioxide in an aqueous menstruum containing microorganisms suitable for converting the substrate to an alcohol, the process comprising:

• a. continuously passing the substrate and the menstruum through a one or more membrane modules arranged within at least one bioreactor of a bioreactor assembly;
• c. maintaining a desired e/C ratio in each of the modules and, if necessary to maintain the desired e/C in a module, adding at least one of carbon monoxide, carbon dioxide or hydrogen to the substrate gas inflow of that module;
• d. maintaining a desired alcohol concentration in each of the modules and withdrawing menstruum from one or modules and/or adding menstruum to one or more modules;
• e. continuously withdrawing a substrate depleted gas phase from at least one of the modules;
• f. continuously or intermittently collecting a portion of said menstruum from one or more of the modules for recovery of alcohol therefrom, said withdrawal being sufficient to maintain the alcohol in said menstruum below a concentration that unduly adversely affects the microorganisms;
• and,
• g. recovering alcohol from the collected menstruum.