High-Performance CO₂ Adsorbent from Interlayer Potassium-Promoted Stearate-Pillared Hydrotalcite Precursors

Abstract

Stearate-pillared layered double hydroxide (LDH) promoted by K 2 CO 3 as a precursor for pre-combustion of a CO 2 adsorbent is presented for the first time. This novel precursor is synthesized from commercial hydrotalcite, one kind of LDH, undergoing acid-aid anionic exchange and wet impregnation processes. The pillared stearate expands the gallery height from 0.28 nm for carbonate-intercalated LDH (almost the diameter of the K ion, 0.276 nm) to a much spatial 3.4 nm for stearate-intercalated LDH, proven by characteristic diffraction peaks in powder X-ray diffraction (PXRD). Transmission electron microscopy (TEM) micrographs and energy-dispersive X-ray spectroscopy (EDX) provide a vivid layout of K and its on-spot composition, respectively, deducing that a well-dispersed K ion promotion exists inside brucite-like layers. Experimental results carried out by a thermogravimetric analyzer (TGA) show striking CO 2 capacity up to 1.93 mmol g −1 at 300°C, 1.7 times higher than that of a conventional K 2 CO 3 -promoted hydrotalcite adsorbent (1.11 mmol g −1 ), and fast adsorption kinetics for this precursor.

Layered double oxide/activated carbon-based composite adsorbent for elevated temperature H 2 /CO 2 separation

“…The syngas must be cooled before entering the separation equipment and has to be heated up after exiting, which leads to heat waste and an increase in the complexity of the system. Elevated temperature pressure swing adsorption (ET-PSA) based on a solid adsorbent takes advantage of the fact that the adsorption performance of the adsorbent improves with the increase in the CO 2 partial pressure at elevated temperature [5]. Previously published research shows that when using elevated temperature H 2 /CO 2 separation technology, the IGCC system efficiency can be 0.6e3.4% higher than that of the low temperature wet H 2 /CO 2 separation method [4].…”

“…The studies of hydrotalcite mainly concentrate on the following four aspects: replacing cations [22e24], replacing/ intercalating anions [5,25], modifying alkalis [26] and coating hydrotalcite on new carriers [27,28]. There are two challenges in current studies of hydrotalcite as a CO 2 absorbent.…”

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

“…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].…”

Experimental Characterization and Mechanistic Simulation of CO2 Adsorption/Desorption Processes for Potassium Promoted Hydrotalcites Sorbent

“…Among carbon capture and storage (CCS) technologies, the elevated temperature pressure swing adsorption (PSA) without cooling the syngas down to ambient temperature is a promising technology for pre-combustion CO2 capture in integrated gasification combined cycle (IGCC) power plant. Potassium promoted hydrotalcite-like compounds (K-HTlc) is widely studied as CO2 adsorbent at elevated temperature (200-400 o C) for its relatively rapid adsorption kinetics and cycle stability [1][2][3][4][5] .…”