Biochars as Potential Adsorbers of CH4, CO2 and H2S.

Methane gas, as one of the major biogases, is a potential source of renewable energy for power production. Biochar can be readily used to purify biogas contaminants such as H₂S and CO₂. This study assessed the adsorption of CH₄, H₂S, and CO₂ onto four different types of biochars. The adsorption dynamics of biochars were investigated in a fixed-bed column, by determining the breakthrough curves and adsorption capacities of biochars. The physicochemical properties of biochars were considered to justify the adsorption performance. The results showed that CH₄ was not adsorbed well by the subjected biochars whereas CO₂ and H₂S were successfully captured. The H₂S and CO₂ breakthrough capacity were related to both the surface adsorption and chemical reaction. The adsorption capacity was in the following order: perilla > soybean stover > Korean oak > Japanese oak biochars. The simultaneous adsorption also leads to a competition of sorption sites. Biochars are a promising material for the biogas purification industry. [ABSTRACT FROM AUTHOR]