Adsorption technology for upgrading biogas to biomethane

Biogas upgrading to biomethane mainly involves the separation of CO2 from the biogas stream, which should be previously purified by elimination of H2S, H2O, and, if present, other impurities. This operation improves its properties as a fuel and broadens its potential applications; it can be carried out by different processes, such as absorption, membrane separation, adsorption, and others. This chapter focuses on the adsorption technology, starting with the introduction of the theoretical aspects related to the thermodynamics and kinetics of this phenomenon. Subsequently, the different regeneration techniques for a cyclic utilization of the adsorbents are presented, together with a brief analysis of the scientific literature on this subject. Finally, the ruling physical-chemical and textural parameters together with key performance indicators of adsorbent materials for an efficient biogas upgrading by adsorption are critically analyzed for their proficient use in cyclic operations.