Elimination of H₂S Contained in Biogas by Metal-supported Active Carbon Adsorbents

Abstract

Metal-supported active carbon adsorbents were applied to remove the small amount of H₂S contained in biogas CH₄. H₂S adsorption experiments using column type-equipment demonstrated that copper-supported active carbon exhibited high H₂S adsorption ability. From the practical point of view, the width and the rate of the adsorption layer were estimated using copper-supported active carbons. Assuming that the metal ion was initially coordinated with oxygen atoms in H₂O molecules, the energy change in substituting a H₂O molecule by a H₂S molecule was calculated using a calculation program for the ab initio molecular orbital method (Gaussian 09). The results of these energy calculations suggest that Cu⁰ and Cu⁺ species have the highest adsorption affinity with H₂S among various metal and metal ions, in agreement with the present experimental results.