Selective separation of carbon dioxide from biogas mixture using mesoporous ceria and zirconium hydroxide

Biogas is considered to be one of the potential and viable renewable energy resources. However, the presence of CO2 in biogas increases the cost of its transportation. Therefore, the removal of CO2 is of utmost essential to ensure the economic viability of the bio-gas utilisation technology. Among the various routes, pressure swing adsorption (PSA) may be considered more economically viable when adsorbent selectivity is high and heat of adsorption is low. In this work, we have synthesized mesoporous cerium oxide (CeO2) and zirconium hydroxide (Zr(OH)(4)) which possess approximately two orders of magnitude higher selectivity for the removal of CO2 from biogas mixture compared to commercial zeolite (Na-Zeolite Y) and commercial granular activated carbon. In addition, the methane slip in CeO2 (0.16%) was five times lower than Zr(OH)(4) (0.62%) and two orders of magnitude lower than activated carbon (18%). The high selectivity and low methane slip of ceria can be attributed to the large number of heterogeneous sites available for selective adsorption of CO2. Based on our results on CO2 selectivity and methane loss, we conclude that CeO2 could be a potential adsorbent for biogas purification using PSA.