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

Abstract

Biogas is considered to be one of the potential and viable renewable energy resources. However, the presence of CO sub(2) in biogas increases the cost of its transportation. Therefore, the removal of CO sub(2) 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 (CeO sub(2)) and zirconium hydroxide (Zr(OH) sub(4)) which possess approximately two orders of magnitude higher selectivity for the removal of CO sub(2) from biogas mixture compared to commercial zeolite (Na-Zeolite Y) and commercial granular activated carbon. In addition, the methane slip in CeO sub(2) (0.16 percent) was five times lower than Zr(OH) sub(4) (0.62 percent) and two orders of magnitude lower than activated carbon (18 percent). The high selectivity and low methane slip of ceria can be attributed to the large number of heterogeneous sites available for selective adsorption of CO sub(2). Based on our results on CO sub(2) selectivity and methane loss, we conclude that CeO sub(2) could be a potential adsorbent for biogas purification using PSA.