Carbon capture in fermentation using blended gaseous substrate
View Patent ↗The disclosure relates to methods of capturing carbon by microbial fermentation of a gaseous substrate comprising CO. The methods include converting CO to one or more products including alcohols and/or acids and optionally capturing CO 2 to improve overall carbon capture. In certain aspects, the disclosure relates to processes for producing alcohols, particularly ethanol, from industrial waste streams, particularly steel mill off-gas.
1. A process for producing at least one product by microbial fermentation of a blended gaseous substrate comprising CO and H 2 , the process comprising:
a) passing a waste stream comprising CO from a steel manufacturing process and a synthesis gas stream comprising CO and H 2 to a blending zone operated at conditions to blend the streams and produce a blended gaseous substrate having a CO:H 2 molar ratio from about 20:1 to about 1:2; and
b) passing the blended gaseous substrate from the blending zone to a bioreactor comprising a culture of at least one microorganism selected from the group consisting of Clostridium, Moorella and Carboxydothermus , the bioreactor operated at conditions to ferment the gaseous substrate to a product selected from the group consisting of alcohols, acids and mixtures thereof.
2. The process of claim 1 where the product is selected from the group consisting of ethanol, acetate and mixtures thereof.
3. The process of claim 1 where the at least one Clostridium microorganism is selected from the group consisting of Clostridium autoethanogenum, Clostridium ljungdahli, Clostridium ragsdalei, Clostridium drakei, Clostridium carboxydivorans and Clostridium scatologenes.
4. A process for producing at least one product by microbial fermentation of a blended gaseous substrate comprising CO and H 2 , the process comprising:
a) passing a waste stream comprising CO from a steel decarburization process and a waste stream from a steel coke oven comprising H 2 to a blending zone operated at conditions to blend the streams and produce a blended gaseous substrate having a CO:H 2 molar ratio from about 20:1 to about 1:2; and
b) passing the blended gaseous substrate from the blending zone to a bioreactor comprising a culture of at least one microorganism selected from the group consisting of Clostridium, Moorella and Carboxydothermus , the bioreactor operated at conditions to ferment the gaseous substrate to a product selected from the group consisting of alcohols, acids and mixtures thereof.
5. The process of claim 4 where the steel coke oven waste stream comprises about 55% H 2 by volume.
6. The process of claim 4 where the product is selected from the group consisting of ethanol, acetate and mixtures thereof.
7. The process of claim 4 where the at least one Clostridium microorganism is selected from the group consisting of Clostridium autoethanogenum, Clostridium ljungdahli, Clostridium ragsdalei, Clostridium drakei, Clostridium carboxydivorans and Clostridium scatologenes.