CO₂ Adsorption on Amine-Functionalized Periodic Mesoporous Benzenesilicas

Abstract

CO2 adsorption was investigated on amine-functionalized mesoporous silica (SBA-15) and periodic mesoporous organosilica (PMO) samples. Hexagonally (p6mm) ordered mesoporous SBA-15 and benzene-PMO (BPMO) samples were prepared in the presence of Pluronic P123 block copolymer template under acidic conditions. Three kinds of amine-containing organosilanes and polyethylenimine were used to functionalize SBA-15 and BPMO. Small-angle X-ray scattering and nitrogen adsorption isotherms showed that these samples featured ordered mesostructure, high surface area, and narrow pore size distributions. Solid-state (13)C- and (29)Si cross-polarization magic-angle spinning NMR spectra showed chemical linkage between amine-containing modifiers and the surface of mesoporous materials. The chemically linked amine-containing modifiers were found to be on both the inner and outer surfaces. N-[3-(trimethoxysilyl)propyl]ethylenediamine-modified BPMO (A2-BPMO) sample exhibited the highest CO2 uptake (i.e., ∼3.03 mmol/g measured on a volumetric adsorption analyzer) and the fastest adsorption rate (i.e., ∼13 min to attain 90% of the maximum amount) among all the samples studied. Selectivity and reproducibility measurements for the A2-BPMO sample showed quite good performance in flowing N2 gas at 40 mL/min and CO2 gas of 60 mL/min at 25 °C.

Insights into CO2 and CH4 Adsorption by Pristine and Aromatic Amine-Modified Periodic Mesoporous Phenylene-Silicas

“…Recently, alkyl amine functionalities (more specifically the N- [3-(trimethoxysilyl)propyl]-ethylenediamine) grafted on the silanols of phenylene-bridged PMO and of SBA-15 were tested in the adsorption of pure CO2 at 25 °C in a pressure range up to 1.2 atm. 38 It was observed that the alkyl amine-PMO adsorbs a larger amount of CO2 at a faster adsorption rate when compared with SBA-15, which demonstrates that the functionalization of PMOs with amines is more relevant than a similar degree and nature of functionalization in silica for the adsorption of CO2. Interestingly, the unmodified SBA-15 silica also adsorbs a smaller amount of CO2 when compared with the unmodified PMO.…”

Nitrogen‐Doped Graphene Quantum Dots Enhance the Activity of Bi2O3 Nanosheets for Electrochemical Reduction of CO2 in a Wide Negative Potential Region

“…[14] Furthermore,t he surface of carbon quantum dots is easily functionalized by amino groups (ÀNH 2 ), which can increase the CO 2 adsorption ability efficiently. [14,15] Al arge CO 2 adsorption capacity is facile to enhance the activity for electrochemical reduction of CO 2 .B ecause of the large number of amino groups on the surface,n itrogen-doped graphene quantum dots (NGQDs) are promising efficient electrocatalysts for CO 2 reduction. [8c] Based on the above analysis results,itisreasonable to assume that the composite electrocatalysts composed of NGQDs and Bi 2 O 3 nanosheet can effectively catalyze the electrochemical reduction of CO 2 .…”

“…[1a,11b,17] However,l ike most catalysts,t he formate FE decreases rapidly at more negative potentials than the optimum potential (a potential for achieving the largest FE). [14,15,19] Consequently,wespeculate that ahigh formate FE at more negative potentials is attributed to the enhanced adsorption capacity of adsorbed CO 2 and OCHO* intermediate.F or most catalysts, the weak adsorption energy of adsorbate results in an insufficient concentration of CO 2 (ads) and reaction intermediates on the catalysts surface for reaction consumption at more negative potentials,w hich leads to CO 2 reduction reactions reaching the mass transfer limit. Obviously,t he introduction of NGQDs significantly enhanced the activity for SnO 2 -NGQDs over awide negative potential range (À0.9 VtoÀ1.3 V).…”

Synthesis and CO2 adsorption behavior of amine‐functionalized porous polystyrene adsorbent

“…Table shows that the amine contents for XAD‐4‐DETA, XAD‐4‐TETA, and XAD‐4‐TEPA are 4.19, 4.69, and 5.15 mmol/g, respectively. On the basis of the Kyohyun Sim mechanism, a higher amine group content of the adsorbent could lead to higher CO 2 adsorption capacity. However, an excess content of amine may block the pores of XAD‐4, which limits the further inner diffusion of CO 2 and ultimately reduces the accessibility of CO 2 molecules to the internal amine groups.…”

“…23 Thus, the amine content was a significant influential factor for CO 2 capture. 24 a higher amine group content of the adsorbent could lead to higher CO 2 adsorption capacity. However, an excess content of amine may block the pores of XAD-4, which limits the further inner diffusion of CO 2 and ultimately reduces the accessibility of CO 2 molecules to the internal amine groups.…”