Syngas Fermentation: Cleaning of Syngas as a Critical Stage in Fermentation Performance

Abstract

The fermentation of syngas is an attractive technology that can be integrated with gasification of lignocellulosic biomass. The coupling of these two technologies allows for treating a great variety of raw materials. Lignin usually hinders microbial fermentations; thus, the thermal decomposition of the whole material into small molecules allows for the production of fuels and other types of molecules using syngas as substrate, a process performed at mild conditions. Syngas contains mainly hydrogen, carbon monoxide, and carbon dioxide in varying proportions. These gases have a low volumetric energy density, resulting in a more interesting conversion into higher energy density molecules. Syngas can be transformed by microorganisms, thus avoiding the use of expensive catalysts, which may be subject to poisoning. However, the fermentation is not free of suffering from inhibitory problems. The presence of trace components in syngas may cause a decrease in fermentation yields or cause a complete cessation of bacteria growth. The presence of tar and hydrogen cyanide are just examples of this fermentation’s challenges. Syngas cleaning impairs significant restrictions in technology deployment. The technology may seem promising, but it is still far from large-scale application due to several aspects that still need to find a practical solution.

Ammonia Can be Currently Considered as one of the Best Green Energy Ally

“…Therefore, other technologies would need to get into play as it would be biomass gasification of forestry material and lignocellulosic wastes [39]. However, gasification technology has to overcome several challenges regarding syngas cleaning, tar production and char quality along with inefficiencies caused by biomass transport logistics and energy densification [40,41].…”

Integrated Biorefinery for a Next-Generation Methanization Process Focusing on Volatile Fatty Acid Valorization: A Critical Review

“…For instance, a recent study demonstrated the feasibility of using syngas generated by the gasification of biogenic residues as a substrate for fermentation to produce short- and medium-chain alcohols using the acetogenic bacterium Clostridium carboxidivorans [ 105 ]. Syngas production (mainly derived from lignocellulosic biomass) and fermentation for microbial conversion of gaseous substrates to various products have been well reviewed in the literature [ 106 , 107 , 108 ].…”

Ammonia Can Be Currently Considered One of the Best Green Energy Allies

“…Therefore, other technologies would need to come into play as it would be biomass gasification of forestry material and lignocellulosic wastes [40]. However, gasification technology has to overcome several challenges regarding syngas cleaning, tar production, and char quality along with inefficiencies caused by biomass transport logistics and energy densification [41,42].…”