CO₂ Adsorption at Elevated Pressure and Temperature on Mg–Al Layered Double Hydroxide

Abstract

CO 2 adsorption at elevated pressure was studied in a Mg−Al (Mg/Al = 3) layered double hydroxide (LDH). The double-layered structure was prepared via a coprecipitation method. The sample's structure and microstructure evolutions were characterized using X-ray diffraction, scanning electron microscopy, N 2 adsorption, and thermogravimetric and calorimetric analyses. The CO 2 adsorption experiments were performed between 5 and 4350 kPa at different temperatures (30−350 °C). Elevated pressure experiments showed that this material was able to adsorb different quantities of CO 2 depending on the thermal evolution of its structure and microstructure. The highest CO 2 adsorption (5.7 mmol/g) was produced at 300 °C before the layered structure had completely collapsed. At these specific conditions the interlayer space was reduced from 7.78 to 4.39 Å. This interlayer change was attributed to the onset of LDH structural collapse. However, at this temperature the adsorption process must be favored over the adsorption−desorption equilibrium, allowing the maximum CO 2 capture.

Regenerable magnesium-based sorbent for high-pressure and moderate-temperature CO2 capture: Physicochemical structures and capture performances

“…5(B)-(D)). These qualitatively illustrate that the chemical sorption of CO 2 is certain to occur during CO 2 capture, which has been also proved by some Literatures [1,2,14,15]. Consequently, it is concluded that the carbonation reaction of Mg(OH) 2 is certain to occur under the investigated capture conditions.…”

“…A variety of solid sorbents for CO 2 capture have been studied and reported in Literatures. According to the CO 2 adsorption mechanisms, these solid sorbents can be classified into two types: physisorbents (microporous and mesoporous inorganic and organic materials such as zeolites [3], silica gel [4], activated carbon [5], and metal-organic frameworks (MOFs) [6]) and chemisorbents (Ca-based materials such as CaO [7], alkali metal-based materials such as NaOH [8], K 2 CO 3 [9] and Na 2 CO 3 [10], and Mg-based materials such as Mg(OH) 2 [1,2], MgO [11][12][13], hydrotalcite [14,15], and alkali metal-promoted hydrotalcite [16][17][18][19]). Usually, these physisorbents and chemisorbents for CO 2 capture are separately used in the pressure/temperature swing adsorption (PSA/TSA) system at relatively low temperatures (even near ambient temperature) and the TSA system at different temperatures [20].…”

“…van Dijk et al [14] investigated the CO 2 and H 2 S co-capture behaviors of the hydrotalcite-based sorbent (a similar sorbent), and considered that the sorbent could simultaneously eliminate CO 2 and H 2 S from the syngas. Ramirez-Moreno et al [15] made some investigations on the microstructure evolutions of the Mg-Al layered double hydroxide sorbent (a similar sorbent), and found that the double-layered structure of the sorbent was completely destroyed and no crystalline phase was detected at 325°C. In order to further understand the adsorption/regeneration processes and CO 2 capture performances of this kind of sorbent, there still needed some additional investigations and/or descriptions.…”

A Review of Layered Double Hydroxides as Intermediate-temperature CO2 Adsorbents

“…Research Progress and Trends of LDH Adsorption on CO 2 Although LHD has many advantages in the adsorption of CO 2 , there were still a lot of problems to be overcome in practical applications. In order to improve the adsorption capacity of LDH, the scholars have studied the conditions of synthesis, modification and compounding.…”

“…Among various carbon dioxide capture and storage (CCS) technical options for CO 2 separation and capture, adsorption of CO 2 on solid adsorbents have been widely investigated. In recent years, layered double hydroxides (LDH) are the most promising candidates for the above applications, due to the characteristics of eco-friendly, cheap, easy to regenerate, wide range of process technology [2]. Especially, LDH as intermediate-temperature (200 ~ 400 ºC) CO 2 adsorbents have been extensively studied due to their optimal adsorption reaction temperature in the industrial flue gas temperature range.…”