Stabilization of NaNO 3 -Promoted Magnesium Oxide for High-Temperature CO 2 Capture

• Published in: Environmental science & technology 2018-10, Vol.52 (20), p.11952, Article acs.est.8b04145
• Main Authors: Triviño, Monica Louise T, Hiremath, Vishwanath, Seo, Jeong Gil
• Format: Article
• Language: English
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.8b04145

NaNO -promoted MgO sorbents are known to achieve enhanced CO sorption uptake but fail to maintain their capacity after multiple sorption-regeneration cycles. In this study, commercially available hydrotalcites (Pural Mg30, Pural Mg70, and synthetic hydrotalcite) were used as stabilizers for NaNO -impregnated MgO (MgONaNO ) sorbents to improve their cyclic stability. Results show that the Mg30-stabilized MgONaNO attained higher and stable overall CO sorption performance as compared to bare MgONaNO after multiple sorption cycles. XRD analyses reveal that the hydrotalcites act as templates for MgCO by restricting the formation of large and nonuniform product crystallites. Furthermore, CO -TPD results show that the hydrotalcites cause a change in the basic sites of the sorbent, which may be attributed to its high interaction with both MgO and NaNO . This interaction becomes stronger as cycles proceed due to the structural rearrangements occurring, thus contributing to the stable behavior of the sorbents. However, these characteristics were not found on MgONaNO and the α-Al O -stabilized samples, thus proving the unique ability of hydrotalcites. From these results, we then derived the formation scheme of MgCO on the hydrotalcite-stabilized sorbents. This study presents a simple yet effective method of improving the stability of molten salt-promoted sorbents with promising potential for industrial use.