CO2 Capture from the Atmosphere and Simultaneous Concentration Using Zeolites and Amine-Grafted SBA-15

• Published in: Environmental science & technology 2011-12, Vol.45 (23), p.10257-10264
• Main Authors: Stuckert, Amy Nicki, Yang, Ralph T.
• Format: Article
• Language: English
• Subjects: Amines - chemistry; Carbon Dioxide - chemistry; Energy and the Environment; Silicon Dioxide - chemistry; Zeolites - chemistry
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es202647a

CO2 capture from the atmosphere and concentration by cyclic adsorption–desorption processes are studied for the first time. New high microporosity materials, zeolite types Li-LSX and K-LSX, are compared to zeolite NaX and amine-grafted SBA-15 with low amine content. Breakthrough performance showed low silica type X (LSX) to have the most promise for application in dry conditions and capable of high space velocities of at least 63 000 h–1, with minimal spreading of the CO2 breakthrough curve. Amine-grafted silica was the only adsorbent able to operate in wet conditions, but at a lower space velocity of 1500 h–1, due to slower uptake rates. The results illustrate that the uptake rate is as important as the equilibrium adsorbed amount in determining the cyclic process performance. Li-LSX was found to have double the capacity of zeolite NaX at atmospheric conditions, also higher than all other reported zeolites. It is further demonstrated that by using a combined temperature and vacuum swing cycle, the CO2 concentration in the desorption product is >90% for all adsorbents in pellet form. This is the first report of such high CO2 product concentrations from a single cycle, using atmospheric air.