Layered Double Hydroxides/Multiwalled Carbon Nanotubes-Based Composite for High-Temperature CO₂ Adsorption

Abstract

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.

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

“…Since the main active component of the layered double hydroxide (LDH)-based CO 2 adsorbent is also MgO [49][50][51][52] , much work has also been performed on the modification of MgO-based mixed oxides adsorbents derived from LDHs with molten salts, as listed in http://engine.scichina.com/doi/10.1016/j.jechem.2017.06.005 [53][54][55][56][57][58] . In 2013, Li et al .…”

“…Furthermore, Bhatta et al . [54] synthesized K 2 CO 3 promoted Mg-Al mixed oxides/multiwalled carbon nanotubes (MWCNTs) composite using the coprecipitation method. The adsorbent exhibited an average working capacity of 0.81 mmol/g over 10 cycles in the temperature range of 30 0-40 0 °C.…”

“…The adsorbent exhibited an average working capacity of 0.81 mmol/g over 10 cycles in the temperature range of 30 0-40 0 °C. The enhanced capacity can be attributed to better contact between gas and surface of active material due to improved particle dispersion [54] .…”

Carbon-layered double hydroxide nanocomposite for efficient removal of inorganic and organic based water contaminants – unravelling the adsorption mechanism

“…The porous carbon sample used for the preparation of C-LDH composite has BET surface area and pore volume of 752 m 2 /g and 1.155 cc/g, respectively. 26 During formation of C-LDH composite, the molecular species of LDH precursors could block partly 28 the interparticle mesopores of carbon particles, thereby decreasing the BET mesopore surface area and pore volume of the composite (Table 1). The pore diameter of the samples is in the range of 3.6-3.9 nm while the sample C4x-LDH shows bimodal pore size distribution at around 1.2 nm and 3.6 nm (inset of Fig.…”

A Review of the Application of Steel Slag in CO2 Fixation

“…It can be seen that the top five regions in the world's crude steel production were China, Europe, America, India, and Japan, respectively, which was accounting for 82.7 % of the total 2. While, the annual production of steel slags is 21 million tons in Europe, 14 million tons in Japan, and over a hundred million tons in China 4–6. Therefore, there are total 130–200 million tons steel slag production in the world every year 7.…”