Sulfuric Acid Modified Bentonite as the Support of Tetraethylenepentamine for CO₂ Capture

Abstract

In this work, an inexpensive and commercially available bentonite was modified by sulfuric acid and explored as the new type of support to immobilize tetraethylenepentamine (TEPA) for CO 2 capture from flue gas. By applying sulfuric acid treatment, the textural properties, in particular, pore volume and surface area of bentonite, were significantly improved. Bentonite treated with 6 M sulfuric acid (Ben_H 2 SO 4 _6M) can reach a pore volume of 0.77 cc/g from that of the parent bentonite of 0.15 cc/g. With the maximum TEPA loading of 50 wt % onto the Ben_H 2 SO 4 _6M sorbent, the maximum CO 2 breakthrough sorption capacity reached 130 mg of CO 2 /g of sorbent at 75 °C under a dry condition. With an addition of moisture to the simulated flue gas, the CO 2 sorption capacity can be further improved to 190 mg of CO 2 at 18 vol% of moisture addition sorbent due to the bicarbonate formation under a wet condition. The TEPA/Ben_H 2 SO 4 _6M sorbents show a good regenerability and thermal stability below 130 °C. The high CO 2 sorption capacity, positive effect of moisture addition, and low capital cost of the raw bentonite materials imply that TEPA/Ben_H 2 SO 4 _6M could be a promising sorbent for cost-efficient CO 2 capture from flue gas. The sulfuric acid treatment was demonstrated as an effective method for bentonite modification to immobilize TEPA for CO 2 capture.

Evaluation of porous clay heterostructures modified with amine species as adsorbent for the CO2 capture

“…It is complicated to compare the CO 2 adsorption data among clay minerals because their crystallinity is strongly influenced by the environmental conditions. Nonetheless, CO 2 adsorption obtained for raw bentonite is in the same range, which is the same range to those reported for kaolinite and bentonite treated with acid, which reaches a CO 2 adsorptin of 0.227 and 0.077 mmol CO 2 g -1 , respectively [48,49]. In the case of the PCH, the linearity of the isotherm diminishes slightly by the stronger interaction adsorbate-adsorbent, obtaining a CO 2 adsorption of 0.640 mmol g -1 at 25 ºC and 1 bar.…”

Modified nanosepiolite as an inexpensive support of tetraethylenepentamine for CO2 sorption

“…Therefore, developing alternative materials as supporting materials with low cost and good hydrothermal stability such as clays is valuable for industrial application. To the best of our knowledge, few authors recently have studied clay minerals such as bentonite, montmorillonite, and kaolinite as supporting materials for CO 2 capture [12,[28][29][30].…”

“…However, the microstructure of clay minerals limits their potential utilization in some separation processes [29]. Some methods can be used to overcome this issue, including acid activation to increase surface area and pore volume, and thus improve the chemical properties of clays.…”

“…O 2 in N 2 . In another work, this group, Wang et al, [29] prepared a composite sorbent using acid modified bentonite and TEPA, and sorption capacity reached 190 mg CO 2 /g ($ 4.31 mmol/g) at 18 vol.% of moisture at 75 1C and15 vol.% CO 2 and 4.5 vol.% O 2 in N 2 .…”

Vapor-enhanced CO2 adsorption mechanism of composite PEI@ZIF-8 modified by polyethyleneimine for CO2/N2 separation

“…The application of some alkaline chemicals to modify the surfaces of conventional adsorbents was an effective approach since CO 2 is acidic molecule [6]. For example, polyethylenimine (PEI) was reported to be grafted or impregnated on conventional porous materials such as activated carbon [7], mesoporous silicas [8], MCM-41 [9], mesoporous alumina [10], clays [11] and chitosan [12]. As a result, CO 2 adsorption capacities of these modified adsorbents had obviously been improved.…”