Nanoporous Materials as H2S Adsorbents for Biogas Purification: a Review

Biogas is one of the most promising renewable sources of energy. However, it is also a gas mixture containing acidic gases, such as H2S, useless for energetic purposes, environmentally harmful and damaging for energy conversion devices. This review focuses on nanoporous materials as adsorbents of H2S for biogas purification processes. Cation-exchanged zeolites and impregnated activated carbons have been thoroughly studied since many years for this application, providing good results, in particular for what concerns activated carbons, despite having a limited regenerability. Amino-functionalized ordered mesoporous silicas produced very interesting results, both in terms of adsorption performances and regeneration capacity, but they are largely untested in large-scale "real-life" applications, and deserve further investigations, in particular for H2S and CO2 discrimination. On the contrary, despite reporting very good results, there are only few papers dealing with H2S adsorption on nanoporous metal organic frameworks.