Surface modification of a low cost bentonite for post-combustion CO2 capture
Introduction
The increased CO2 emission into the earth's atmosphere has raised serious concerns regarding global warming [1], and considerable effort has been made over the last decade to develop carbon capture and storage (CCS) technologies to reduce the CO2 levels. Currently, the large-scale separation of CO2 by liquid phase amine-based absorption is in operation throughout the world. However, they suffer a number of drawbacks, including the requirement for a large amount of energy for solvent regeneration, solvent degradation in the presence of oxygen, and equipment corrosion [2]. Compared to absorption based on aqueous amine and ammonia, adsorption is considered to be more promising for capturing CO2 from flue gases, offering possible energy savings. Currently, both physical and chemical adsorption processes based on solid adsorbents, such as zeolites [3], [4], [5], [6], porous carbon [7], [8], [9], [10], [11], alumina [12], metal organic frameworks (MOFs) [13], [14], [15], [16], basic oxide and hydrotalcite materials [17], [18], [19], [20], [21] and functionalized nanoporous materials [22], [23], [24], [25], [26], [27], [28], [29], are being actively investigated.
Saving materials and energy has always been an important concern for industries. From this perspective, it is imperative to develop low cost and efficient solid materials for CO2 capture. In this study, a CO2 adsorbent based on a mineral bentonite was proposed. Bentonite has been investigated for a wide range of industrial applications owing to its specific physical and chemical properties, as well as its abundance in most continents of the world and low cost [30]. Bentonite has been studied as an adsorbent for contaminants such as heavy metals [31] or phenolic compounds [32] in waste water. Owning to its porous nature, bentonite can incorporate functionalities to form composite material for adsorption, catalysis and separations. Tomul, for example, reported adsorption and catalytic properties of bentonites pillared with iron (Fe), chromium (Cr) and iron/chromium pillars with different Fe/Cr molar ratios [33]. However, there have been only very few reports on the application of bentonite for CO2 capture. Venaruzzo et al. [34] reported CO2 adsorption by bentonite clay materials in both their natural state and after acid treatments and Azzouz et al. [35] examined CO2 capture by montmorillonite (a purified bentonite) intercalated with polyol dendrimers.
In this report, a bentonite was modified with PEI (polyethylenimine) using a physical impregnation method and the resulting hybrid material was examined as an adsorbent for CO2. Several groups have previously reported that PEI-modified mesoporous silicas are highly effective for CO2 capture [22], [23], [24]. Since these mesoporous silica materials must be prepared using pure chemicals in the presence of a costly surfactant template that needs to be removed by calcination afterward [36], [37], we seek to study bentonite as a support material for PEI to form a hybrid CO2 adsorbent; bentonite is easily available at low cost and does not require any particular pretreatment to use it as a support. Herein, after preparing and characterizing bentonites with different PEI loadings, their ability to capture CO2 under different operating conditions as well as their stability in cyclic CO2 adsorption–desorption runs were investigated.
Section snippets
Materials and PEI-impregnation on bentonite
The bentonite clay mineral was obtained from Xinyang, Henan province, PR China. Bentonite was pretreated at 150 °C in a vacuum before the N2 adsorption–desorption measurement and amine impregnation. Zeolite 13X, activated carbon (Darco G-60, 100 mesh) and ZIF-8 were purchased from Sigma–Aldrich for comparison as an adsorbent for CO2.
PEI was introduced to bentonite using the procedure reported by Xu et al. [22]. In a typical preparation, PEI (Aldrich, average molecular weight of 600 by GPC,
Characterization
Fig. 2 shows a scanning electron microscopy (SEM) image and EDX analysis results of the bentonite clay mineral. The chemical composition revealed atomic percentages of 73.93 (O), 20.6 (Si), 3.75 (Al), 1.21 (Mg), 0.35 (Ca) and 0.15 (Fe), indicating silica and alumina as the major constituents of bentonite, along with traces of iron, magnesium and calcium oxides [34]. Fig. 3 shows the XRD patterns of bentonite before and after PEI incorporation. The XRD pattern of bentonite revealed the
Conclusions
A low cost bentonite was modified by PEI (polyethylenimine) through a physical impregnation method. Bentonite in its natural state exhibited negligible CO2 uptake due to weak physical adsorption by surface. After surface modification by PEI, the CO2 uptake increased significantly, where CO2 was captured primarily by introduced amine species through a chemisorption process. Owing to smaller pore volume, the CO2 uptake of PEI-modified bentonite was lower than those usually achieved by
Acknowledgement
This work was supported by Plasma Research Center at Inha University, Korea (2012).
References (38)
- et al.
Advances in CO2 capture technology—the U.S. Department of energy's carbon sequestration program
International Journal of Greenhouse Gas Control
(2008) - et al.
CO2 adsorption in Y and X zeolites modified by alkali metal cation exchange
Microporous and Mesoporous Materials
(2006) - et al.
CO2 adsorption over ion-exchanged zeolite beta with alkali and alkaline earth metal ions
Microporous and Mesoporous Materials
(2010) - et al.
Efficient carbon dioxide capture over a nitrogen-rich carbon having a hierarchical micro-mesopore structure
Fuel
(2012) - et al.
CO2 capture by adsorption with nitrogen enriched carbons
Fuel
(2007) - et al.
CO2 capture using mesoporous alumina prepared by a sol–gel process
Chemical Engineering Journal
(2011) - et al.
Microwave enhanced synthesis of MOF-5 and its CO2 capture ability at moderate temperatures across multiple capture and release cycles
Chemical Engineering Journal
(2010) - et al.
Carbon dioxide adsorption over zeolite-like metal organic frameworks (ZMOFs) having a sod topology: Structure and ion-exchange effect
Chemical Engineering Journal
(2011) - et al.
Equilibria and kinetics of CO2 adsorption on hydrotalcite adsorbent
Chemical Engineering Science
(2000) - et al.
Reactivity of CaO derived from nano-sized CaCO3 particles through multiple CO2 capture-and-release cycles
Chemical Engineering Science
(2009)
Calcium oxide as high temperature CO2 sorbent: effect of textural properties
Materials Letters
Preparation and characterization of novel CO2 “molecular basket” adsorbents based on polymer-modified mesoporous molecular sieve MCM-41
Microporous and Mesoporous Materials
CO2 adsorption on branched polyethyleneimine-impregnated mesoporous silica SBA-15
Applied Surface Science
Physical and chemical properties of some bentonite deposits of Kimolos Island, Greece
Applied Clay Science
Removal of Pb(II), Cd(II), Cu(II), and Zn(II) from aqueous solutions by adsorption on bentonite
Journal of Colloid and Interface Science
Adsorption of phenol by bentonite
Environmental Pollution
Adsorption and catalytic properties of Fe/Cr-pillared bentonites
Chemical Engineering Journal
Modified bentonitic clay minerals as adsorbents of CO, CO2 and SO2 gases
Microporous and Mesoporous Materials
Carbon dioxide retention over montmorillonite–dendrimer materials
Applied Clay Science
Cited by (55)
Enhanced CO<inf>2</inf> adsorption of PEHA/sepiolite adsorbent by zirconium accelerator in post-combustion
2023, Separation and Purification TechnologyResearch progress of clay minerals in carbon dioxide capture
2022, Renewable and Sustainable Energy ReviewsComplexant-montmorillonite nanocomposites for heavy metal binding in sulfide tailing
2022, Journal of Materials Research and TechnologyCitation Excerpt :As well as Table 1 displayed specific surface area, total pore volume, micro pore volume and average pore diameter. As can be seen from Fig. 3, the pores of montmorillonites were mainly mesoporous [40], thus montmorillonites could be determined as mesoporous material. At the same time, the average pore diameter of montmorillonites in Table 1 were all between 2 and 50 nm, which strongly proved that point.
Adsorption studies of carbon dioxide and anionic dye on green adsorbent
2022, Journal of Molecular StructureApplication of clay minerals and their derivatives in adsorption from gaseous phase
2021, Applied Clay Science