The use of an industrial by-product as a sorbent to remove CO2 and H2S from biogas.

Abstract: Raw biogas, produced by anaerobic digestion of organic matter, is a methane-rich combustible gas. The CH₄ content can be upgraded to reach the natural gas composition for vehicle fuel use (bio-CNG) or injection into the gas grid. This upgrading is performed by CO₂ removal and pollutants treatment (H₂S, water, etc.). The accelerated carbonation on BOF slag, a by-product from the steel industry containing calcium and iron oxides, was studied as a solution. The purpose of this work was to study the potential of slags to remove simultaneously CO₂ with CaO (carbonation) and H₂S with Fe₂O₃ (sulfuration) under atmospheric conditions. Firstly, batch experiments have confirmed the reactivity among CO₂, H₂S and slag. Removal capacities of 63 and 140 were estimated. The effect of the amount of water in the mix biogas/slag was studied on treatment performances, and an optimal L/S range between 0.05 and 0.2 L_water/kg_BOF was found. Secondly a field scale column experiment has been performed to treat the biogas of a pilot digester. This test under dynamic conditions using a BOF slags filter has given promising results (73 ). [ABSTRACT FROM AUTHOR]