Efficient Recovery of Carbon Dioxide from Flue Gases of Coal-Fired Power Plants by Cyclic Fixed-Bed Operations over K₂CO₃-on-Carbon

Abstract

An efficient chemical absorption method capable of cyclic fixed-bed operations under moist conditions for the recovery of carbon dioxide from flue gases has been proposed employing K2CO3-on-carbon. Carbon dioxide was chemically absorbed by the reaction K2CO3 + CO2 + H2O ⇄ 2KHCO3 to form potassium hydrogencarbonate. Moisture, usually contained as high as 8−17% in flue gases, badly affects the capacity of conventional adsorbents such as zeolites, but the present technology has no concern with moisture; water is rather necessary in principle as shown in the equation above. Deliquescent potassium carbonate should be supported on an appropriate porous material to adapt for fixed-bed operations. After breakthrough of carbon dioxide, the entrapped carbon dioxide was released by the decomposition of hydrogencarbonate to shift the reaction in Eq.1 in reverse on flushing with steam, which could be condensed by cooling to afford carbon dioxide in high purity. Among various preparations of alkaline-earth carbonates (X2CO3, X = Li, Na, K) on porous materials, K2CO3-on-activated carbon revealed excellent properties for the present purpose. Preparation and characterization of K2CO3-on-carbon and illustrative fixed-bed operations under flue gas conditions in laboratory columns and a bench-scale plant are described.

Feasibility of CO2 adsorption by solid adsorbents: a review on low-temperature systems

“…Al 2 O 3 impregnated with calcined K 2 CO 3 (K 2 CO 3 /Al 2 O 3 ) in particular, appeared to have large surface area, high attrition strength and high mechanical strength Chen et al 2012;Zhao et al 2013). Alkali metal-based adsorbents used chemisorption to capture CO 2 therefore effort is needed for regeneration (Hayashi et al 1998). For regeneration, adsorbent with captured CO 2 is transported to calcination chamber where at moderate temperature of 120-210°C the bicarbonate decomposes and releases CO 2 /H 2 O mixture.…”

Adsorption of Carbon Dioxide on Aminosilane-modified Mesoporous Silica

“…Therefore, a new adsorbent which preferably adsorbs CO2 in the presence of water vapor is required to develop a simple and energy-efficient process by elimination of the dehumidification process. Hydrated potassium carbonate supported on active carbon can absorb CO2 from gas containing water vapor 4) . Solid sorbents in which amines are supported on high surface area supports are also promising as sorbents for CO2 separation 5), 6) .…”

Preparation of a Low-Cost K2CO3/Al2O3 Sorbent for CO2 Capture at Flue-Gas Operating Conditions

“…However, when CO 2 reacts with Na 2 CO 3 , the rate of global carbonation is rather slow (Zhao et al 2009). The CO 2 adsorption and regeneration using potassium-based sorbents with several supports such as activated carbon (Hirano et al 1995;Hayashi et al 1998;Shigemoto et al 2006), TiO 2 , SiO 2 , MgO, ZrO 2 , CaO and Al 2 O 3 were also reported in previous studies (Okunev et al 2000(Okunev et al , 2003Lee et al 2004;Liang et al 2004). Al 2 O 3 is one of the ideal materials used as a sorbent support.…”