Syngas Cleaning
Crude syngas from the biomass gasifier contains impurities such as solid ash with metal oxides, carbonates, silicas, and tars; therefore it is necessary to clean the syngas before many applications, including the metal-catalyzed or microorganism-based biocatalyzed conversions to ethanol. Biomass syngas cleaning is an active research
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Table 11.3 Common biomass syngas impurities and their highest reported concentrations.
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area and has been reviewed in recent literature [1,19]. The amount of impurities in the biomass-derived syngas totally depends on the factors like reactor design, operating conditions and type of biomass used in the reactor. However, it is interesting to see the maximum concentrations reported for different impurities before the purification, and Table 11.3 summarizes these maximum concentrations reported for common impurities.
The gas cleaning can basically be divided into two types: dry hot gas cleaning and wet gas cleaning. In addition to these, tar treatment can also be considered as a part of the syngas cleaning process.