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In recent years, a great deal of interest has been shown for high-temperature adsorption of CO 2 on hydrotalcitelike compounds (HTlcs). Numerous efforts have been undertaken to enhance the CO 2 capture property of HTlcs, including alkali-metal impregnation, use of support materials, and modification of chemical composition. The present work demonstrates the applicability of coal-derived graphitic material (CGM) as an effective support for neat as well as K 2 CO 3 -promoted Mg−Al HTlc, enhancing the CO 2 adsorption capacity. Both surface area and basic site density affect the adsorption capacity. The K 2 CO 3promoted CGM-supported Mg−Al HTlc exhibited a fresh adsorption capacity of 1.10 mmol g −1 at 300 °C under a total pressure of 1 bar. After the initial drop, it maintained an average working capacity of 0.42 mmol g −1 during nine cycles of adsorption− desorption in the temperature range of 300−400 °C. The Yoon−Nelson kinetic model fit well with the experimental data.

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Layered double hydroxides (LDH)-derived mixed metal oxides (MMO) are considered as promising solid sorbents for CO2 capture in the temperature range of 350–500 °C. Accordingly, they find potential applications in the sorption enhanced water–gas shift process and in removal of CO2 from hot flue gas/syngas. Numerous strategies have been explored to improve the CO2 capture property of LDH-derived MMO under the conditions of intended applications. These strategies include novel sorbents by replacement of cations and intercalation of organic anions on Mg–Al LDH, development of LDH-based hybrid/composite materials, optimization of synthesis conditions to control particle size, and method development for different types of alkali impregnation. The present work involves synthesis of a Mg–Al LDH/multiwalled carbon nanotubes (MWNTs) composite and explores its applicability for CO2 capture under dry conditions. Additionally, K2CO3 is impregnated onto the composite to study the effect of alkali promotion. The K2CO3-promoted Mg–Al LDH/MWNT composite exhibited a fresh adsorption capacity of 1.12 mmol g–1 at 300 °C under a total pressure of 1 bar. The enhanced CO2 sorption capacity of composites in comparison with their pristine counterparts can be attributed to improved particle dispersion. Further, the K2CO3-promoted Mg–Al LDH/MWNT composite shows an average working capacity of 0.81 mmol g–1 over 10 cycles in the temperature range of 300–400 °C. The deactivation model provides excellent predictions of the experimental CO2 breakthrough curves obtained with various sorbents. The values of model parameters are comparable with those reported in the literature.

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