Removing Undesirable Vocs from Biogases Using the Electrochemical Swing Adsorption onto Activated Carbon Fiber Cloths

Introduction The development of alternative and renewable energies is one of the crucial opportunities exhibited by governments to remediate the diminishing resources of the fossil feedstock. Biogases collected from landfill, digester and wastewater plants constitute a large and disposable supply to produce a rich methane stream, though these resources remain mostly unused. The biogas should be upgraded into a methane-rich stream. Indeed, biogases are complex gaseous mixtures, which consist in a mixture of methane (CH4) and carbon dioxide (CO2), but also low amounts of hydrogen sulfide (H2S) and traces of volatile organic compounds (VOCs). On the challenge is then to find a reliable and sustainable process for the removal of the VOCs. Adsorption onto activated carbons is likely to be one of the most promising technologies. Indeed, adsorption is mostly unselective and is able to remove a large variety of VOCs. Several forms of adsorbents are available. Amongst these carbon materials, activated carbon fiber cloths (ACFCs) have been compared to granular activated carbons, focusing onto the VOCs in biogases. Between granular and fiber cloth materials, the adsorption capacities of the latter were shown to be at least equal but, often, larger than the granular activated carbons [1]. In addition, the electrothermal swing adsorption is achievable with activated carbon fiber cloths (ACFCs) and, if conducted intelligently, this regeneration reduces the energetic costs of the process.