The potency of monoethanolamine in biogas purification and upgrading

Abstract

Biogas has been exploited as one of the alternative sources of renewable energy having the potential to replace fossil fuels. It contains impurities when raw, as it consists of 50–70% methane (CH4), 30–50% carbon dioxide (CO2) and trace gases such as hydrogen sulfide (H2S). Chemical absorption is often a preferred purification technique in industrial applications because it has high efficiencies, removes H2S completely, operates at low pressures, and has higher reaction rates. The focus of this study is on amines as they are widely used worldwide to purify biogas. A continuous system was used where 1 L digester was used for biogas production which was bubbled through an absorbent in 500 mL gas washing bottle. The gas exiting the absorption column was analyzed using Gas Chromatography. The methane yield obtained in this study was higher because MEA is a good absorbent. The biomethane potential was found to be 0.40 m3 CH4/kg VS (volatile solids). An increase in concentration resulted in increased co2 absorption capacity and rate, an average of 76%, 78%, and 84% vol from an initial concentration of 52% vol were achieved for the respective concentrations. The CH4 content of the purified biogas improved with increasing temperature. The removal efficiency of carbon dioxide increased from 66% at room temperature to 77% at 40 °C. Temperature of the solvent increased the absorption capacity and carbon dioxide removal efficiency of the process.