High efficiency nanocomposite sorbents for CO2 capture based on amine-functionalized mesoporous capsules

Abstract

Increases in atmospheric carbon dioxide gas have been linked to increasing use of fossil fuels over the past century. Post-combustion capture has the greatest near-term potential for reducing CO 2 emissions. Solid sorbents provide a promising alternative to conventional amine solutions for CO 2 capture. However, practical CO 2 capture applications have been impeded primarily by limited sorbent capacity and recyclability. Here we present a novel CO 2 capture platform based on oligomeric amines supported on specially engineered mesoporous hollow particles (mesoporous capsules). This new design leads to an exceptional capture capacity of up to 7.9 mmol g -1 under simulated flue gas conditions outperforming both conventional monoethanolamine solutions and other current solid amine impregnated sorbents. In addition to their outstanding CO 2 capture capacity, the sorbents are readily regenerated at relatively low temperature and exhibit good stability and recyclability. A novel high efficiency nanocomposite sorbent for CO 2 capture has been developed based on oligomeric amines (polyethylenimine, PEI, and tetraethylenepentamine, TEPA) functionalized mesoporous silica capsules. The newly synthesized sorbents exhibit extraordinary capture capacity 10 up to 7.9 mmol g -1 under simulated flue gas conditions (pre-humidified 10% CO 2 ). The CO 2 capture kinetics were found to be fast and reached 90% of the total capacities within the first few minutes. The effects of the mesoporous capsule features such as particle size and shell thickness on CO 2 capture capacity were investigated. Larger particle size, higher interior void volume and thinner mesoporous shell thickness all improved the CO 2 capacity of the sorbents. PEI impregnated 15 sorbents showed good reversibility and stability during cyclic adsorption-regeneration tests (50 cycles).

A Review of CO2 Capture by Absorption and Adsorption

“…At high temperature, the high CO 2 adsorption capacity is possibly due to the high diffusion rate of CO 2 into bulklike PEI and the increasing reaction rate of CO 2 with PEI. The similar observation was also reported by HeydariGorji and Sayari (2011) and Qi et al (2011). Song's group further studied the effect of moisture on CO 2 capture using the PEI/MCM-41 and showed that the CO 2 adsorption capacity was increased from 2.03 mmol/g for an anhydrous flow containing 15% of CO 2 to 2.84 mmol/g for a flow containing 10% of moisture and 13% of CO 2 .…”

Solid Adsorbents for Low-Temperature CO2 Capture with Low-Energy Penalties Leading to More Effective Integrated Solutions for Power Generation and Industrial Processes

“…% (75°C and 1 bar) with fast adsorption kinetics was observed (Qi et al, 2012). Similar capacities were achieved from the same group by using mesoporous SiO 2 capsules as a support (Qi et al, 2011), the measured pore volume of the capsules was not high, however, the hollow cores provided abundant space for the accommodation of amines, leading to the exceptionally high adsorption capacities.…”

“…Basically, owing to the higher concentration of amine groups, larger amounts of primary amine, and lower viscosity, higher capacities can be obtained by using TEPA as compared with that of PEIs. However, the cyclic stability of using TEPA is questionable due to its lower thermal stability which led to amine loss during desorption at elevated temperatures (Chen et al, 2009;Liu et al, 2010;Qi et al, 2011). A similar theory can be applied to linear PEI as well.…”

Mesoporous amine‐bridged polysilsesquioxane for CO2 capture

“…3 Most of advanced amine-supported sorbents up to now have been synthesized by the immobilization of amines into mesoporous supports via one of the following strategies: post-grafting, wet impregnation and cocondensation of aminosilanes and tetraalkoxysilanes. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Although sorbents with relatively high amine loadings can be achieved, post-grafting and wet impregnation involve multi-step synthesis in which the supporting materials are separately prepared. In addition, the increase of amine content of the sorbents comes usually at the expense of surface area and pore volume available for CO 2 capture ultimately compromising the performance of the sorbents.…”

“…The two-stage adsorption behavior is typical of other amine-based solid sorbents 3, 4, 15 and has been attributed to CO 2 diffusion resistance in the sorbents. [3][4][5]16 The adsorption kinetics of the sorbent was also investigated gravimetrically in simulated flue gas (prehumified 10% CO 2 ) at 25 o C under ambient pressure. The activated sorbent was first equilibrated in the pre-humified N 2 at 25 o C for 4 h. A weight gain of ~ 8 wt % was attributed to the adsorption of moisture (see Fig.…”