Aqueous miscible organic-layered double hydroxides with improved CO2 adsorption capacity

• Published in: Adsorption : journal of the International Adsorption Society 2020-10, Vol.26 (7), p.1127-1135
• Main Authors: Zhu, Xuancan, Chen, Chunping, Shi, Yixiang, O’Hare, Dermot, Cai, Ningsheng
• Format: Article
• Language: English
• Subjects: Acetone; Adsorbents; Alkali metals; Carbon dioxide; Carbon sequestration; Chemistry; Chemistry and Materials Science; Commercialization; Engineering Thermodynamics; Ethanol; Heat and Mass Transfer; High temperature; Hydrogen bonding; Hydroxides; Impregnation; Industrial Chemistry/Chemical Engineering; Miscibility; Morphology; Potassium carbonate; Solvents; Surfaces and Interfaces; Thin Films; Work capacity
• ISSN: 0929-5607; 1572-8757
• DOI: 10.1007/s10450-020-00209-4

Potassium-promoted layered double hydroxide (LDH)-derived materials are suitable elevated temperature CO 2 adsorbents for pre-combustion CO 2 capture. A challenge for the commercialization of LDHs as efficient CO 2 adsorbents is their low capacities ( ca. 0.5–0.6 mmol/g@400 °C) due to their hydrogen-bonded stacked structure. In this study, the aqueous miscible organic solvent treatment (AMOST) was used to exfoliate Mg 3 Al–CO 3 LDH into nanosheets with a flower-like morphology, resulting in high surface areas of 287 and 212 m 2 /g for CC1 (washed with ethanol) and CC2 (washed with acetone), respectively. The exfoliated LDH structure exposed more interlayered CO 2 active sites and promoters for alkali metal modification. Six impregnation solvents, water, acetone, ethanediol, ethanol, DMAC, and methanol were screened to optimize the CO 2 uptake of 20 wt% K 2 CO 3 -promoted CC1. K 2 CO 3 /CC1(ed) using ethanediol as the impregnation solvent reached a CO 2 working capacity of 1.46 mmol/g at 400 °C in the first cycle and 1.23 mmol/g after 10 cycles, twice the capacity of the commercial K 2 CO 3 /MG70. Material characterization indicated that the unexpectedly high performance of K 2 CO 3 /CC1(ed) could be attributed to the uniform K + dispersion on the surface of K 2 CO 3 /CC1(ed) rather than bulk phase formation and the release of the residual solvent during calcination that could generate more paths for CO 2 diffusion.