Alkali Carbonate Molten Salt Coated Calcium Oxide with Highly Improved Carbon Dioxide Capture Capacity

Abstract

CO2 reduction is crucial if the effects of this gas on global warming are to be alleviated. We report for the first time an alkali carbonate molten salt promoted CaO‐based CO2 sorbent with CO2 capture performance superior to that of neat CaO. The influences of chemical composition, loading, and melting temperature of the (Li–Na–K)2CO3 molten salts and of the calcination and adsorption temperatures on CO2 capture were evaluated systematically. The microstructural and morphological evolution of the samples during CO2 adsorption was studied by X‐ray diffraction, scanning electron microscopy, and Fourier‐transform infrared spectroscopy analyses. The (Li–K)2CO3 molten salt coating was found not only to promote CO2 uptake but also to facilitate CO2 desorption from CaO. In particular, at low temperatures of 500 and 600 °C, the CO2 capture capacity increased significantly from 1.19 and 3.26 mmol g−1 to 6.93 and 10.38 mmol g−1, respectively. The melting point of the molten salts was also a crucial factor in the improvement of CO2 uptake. Kinetic studies based on fractal‐like models indicated that the rate coefficients for (Li–K)2CO3/CaO were approximately 3.3 to 3.8 times larger than those for neat CaO. The coating of alkali carbonate molten salts is believed to prevent the formation of a rigid CaCO3 layer on the surface of the CaO particles and to provide continuous delivery of CO32− to promote CO2 capture. During the CO2 adsorption/desorption cycling tests, (Li–K)2CO3/CaO resulted in a stable and reversible CO2 uptake of 6.0–6.3 mmol g−1, which is much higher than that of neat CaO (2.0 mmol g−1).

Molten salts-modified MgO-based adsorbents for intermediate-temperature CO2 capture: A review

“…sorption enhanced water gas shift (SEWGS) at intermediate temperatures (20 0-40 0 °C) [9][10][11] . Typically, solid adsorbents show potential application for CO 2 capture in terms of a wide range of operating temperatures, low cost and high uptake capacity [7,12] .…”

Solid‐Waste‐Derived Carbon Dioxide‐Capturing Materials

“…[184][185][186] In addition to the high capturec apacity (17.86 mmol g À1 ), the main advantages of CaO-based CO 2 sorbents are environmental friendliness, nontoxicity,s uitability for use in pre-and postcombustion processes, easy use in fluidized-bed reactors, and the possibility for using spent sorbents for cementp roduction. [184][185][186] In addition to the high capturec apacity (17.86 mmol g À1 ), the main advantages of CaO-based CO 2 sorbents are environmental friendliness, nontoxicity,s uitability for use in pre-and postcombustion processes, easy use in fluidized-bed reactors, and the possibility for using spent sorbents for cementp roduction.…”

“…The utilization of calcium oxide (CaO)-baseds orbents in CO 2 captureh as attracted tremendous attention,o wing to as eries of advantages over other sorbents. [184][185][186] In addition to the high capturec apacity (17.86 mmol g À1 ), the main advantages of CaO-based CO 2 sorbents are environmental friendliness, nontoxicity,s uitability for use in pre-and postcombustion processes, easy use in fluidized-bed reactors, and the possibility for using spent sorbents for cementp roduction. [187][188][189] However,t he main problems of CaO-based sorbents are low reversibility and easy sintering during the sorption/desorptionp rocess.…”

A facile Solvent/Nonsolvent Preparation of Sintering‐Resistant MgO/CaO Composites for High‐Temperature CO2 Capture

“…[8] Another extensively studied technology for CO 2 capture is calcium looping, which is based on the reversible carbonation and calcination of CaO (CaO + CO 2 ↔CaCO 3 ). [9] CaO is promising for CO 2 capture because it possesses high stoichiometric CO 2 uptake capacity (17.86 mmol g À 1 ), [10] fast reaction kinetics, and low price. [11] Moreover, the calcium looping process has been demonstrated in pilot scale facilities, e. g. La Pereda 1.7 MW th pilot plant.…”