Selective separation of CO2 and CH4 for biogas upgrading on zeolite NaKA and SAPO-56. (15th January 2016)

• Record Type: Journal Article
• Authors: Bacsik, Zoltán; Cheung, Ocean; Vasiliev, Petr; Hedin, Niklas
• Is Part Of: Applied energy. Volume 162(2016)
• Page Start: 613
• Page End: 621
• Publication Date: 2016-01-15
• Subjects: Carbon dioxide/methane separation -- Biogas upgrading -- CO2 adsorption -- CH4 adsorption -- Zeolite NaKA -- SAPO-56; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2015.10.109
• Languages: English
• ISSNs: 0306-2619

Abstract

Graphical abstract: Highlights: Commercial and potential adsorbents were investigated for separation of CO2 and CH4 . Zeolite |Na12− x K x |-LTA (1.8 ⩽ x ⩽ 3.2) has good CO2 but almost no CH4 uptake. SAPO-56 has a high CO2 working capacity and high CO2 /CH4 selectivity. Abstract: Several commercial and potential adsorbents were investigated for the separation of CO2 from CH4, which is relevant for the upgrading of raw biogas. The main focus of the paper was on the working capacities and selectivities of the adsorbents for a generic vacuum swing adsorption (VSA) process. Zeolites 4A and 13X had good estimated CO2 -over-CH4 selectivities and reasonably high working capacities for the removal of CO2 . A variant of zeolite A – |Na12 − x K x |-LTA (with 1.8 ⩽ x ⩽ 3.2), had at least the same working capacity as zeolite 4A but with a significantly improved selectivity. Hence, the environmentally important "CH4 slip" can be minimized with this |Na12 − x K x |-LTA sorbent. If a high working capacity for CO2 removal is the most important characteristic for a VSA process, then silicoaluminum phosphate, specifically SAPO-56, appeared to be the best candidate among the studied sorbents. In addition, SAPO-56 had a substantially high estimated CO2 -over-CH4 selectivity with a value between ∼20 and 30.