Comparison of Various Alkaline Solutions for H 2 S/CO 2 ‐Selective Absorption Applied to Biogas Purification

Biogas is a common renewable energy resource. A very important stage of biogas upgrading, studied in the present work, is its purification from H 2 S traces. The selective absorption of H 2 S and CO 2 into oxido‐alkaline solutions containing hydrogen peroxide and into amine solutions was compared by performing absorption test runs in a cables‐bundle scrubber at 293.15 K and atmospheric pressure. The absorption rate and selectivity for H 2 S over CO 2 were determined for various solute partial pressures, different alkaline absorbents and hydrogen peroxide concentrations in the scrubbing liquid, and different pH values. Higher H 2 S‐selective absorption performances with oxido‐alkaline solutions than with amine solutions could be observed provided that the solution is at a low pH value (9.5) and contains a sufficient hydrogen peroxide concentration.