CO{sub 2} Capture by Sub-ambient Membrane Operation

MIL-101(Cr) Polymeric Fiber Adsorbents for Sub-Ambient Post-Combustion CO2 Capture

“…One recently considered approach to post-combustion CO 2 capture focuses on extensive pretreatment of the gas stream, including pressurization, dehydration, and cooling to sub-ambient conditions, to improve the sorption–desorption performance of the adsorbent material. Hasse et al explored this area widely for membrane applications, and more recently, this work has been extended to pressure swing adsorptive separations as well. − Interestingly, while this pretreatment results in high capital costs of required pretreatment unit operations, in some cases where the materials are selected to take the most advantage of the increased sorption capacity, this cost can be offset by improved separation unit performance, resulting in costs between $35 and $80 per tonne of CO 2 captured. − While this trade-off appears counterintuitive, as compression to 12–20 bar combined with cooling to 253–223 K will lead to costly capital equipment, the reduction in required adsorbent mass or membrane area has shown in multiple independent studies to shift the system cost. While these conditions may seem unconventional, the elevated pressure condition enables the sub-ambient operating temperature.…”

“…The sorbent loading was confirmed to match expectations using thermogravimetric analysis and N 2 physisorption. Fibers were determined to have very high (>4 mmol CO 2 /g fiber ) adsorption capacity at 243 K and 2 bar CO 2 , which is the feed condition for the sub-ambient post-combustion capture processes previously described in the literature. − Fixed bed breakthrough experiments were used to assess the performance of the fiber sorbents before use in a proof-of-concept single-bed pressure swing adsorption system.…”