Development of Amine-Functionalized Silica Foams with Hierarchical Pore Structure for CO₂ Capture

Abstract

A novel mesocellular silica foam (MCF) support were synthesized, which has different pore volumes and two different sizes of windows on the spherical cells. Tetraethylenepentamine (TEPA)-functionalized MCF adsorbents were then prepared for CO2 capture. The effects of support structure, capture temperature, SO2, and NO2 on the CO2 capture were investigated. The results show that the hierarchical window structure can improve the dispersion of amine species in the silica foams. In situ diffuse reflectance infrared Fourier transform spectroscopy results indicate that more adsorption sites can be exposed in the pores at high temperature for CO2 capture. The MCF-TEPA60% has the optimal capture amount of 4.75 mmol/g with 15 vol % CO2 at 75 °C. The SO2 and NO2 have a negative influence on the adsorption and regeneration properties of adsorbent due to the production of byproducts. However, the MCF-0.8-TEPA60% can maintain outstanding carbon dioxide adsorption capacity during 10 regeneration cycles.

The dynamic CO2 adsorption of polyethylene polyamine-loaded MCM-41 before and after methoxypolyethylene glycol codispersion

“…[1][2][3] Solid amine adsorption technology, with weak corrosivity, highly efficient adsorption performance and low regeneration energy consumption, is recognized as an effective method. [4][5][6][7] So far the study of amine-loaded solid sorbents mainly focuses on immobilizing amines onto the inner surface of porous supporting materials, such as metal-organic frameworks (MOFs), [8][9][10][11][12][13] mesoporous molecular sieves, 14-22 silicas [23][24][25][26][27][28][29][30][31] and so on. [32][33][34][35][36][37][38][39][40] Chen et al incorporated polyethyleneimine (PEI) into mesoporous zeolite 13X prepared by pore-expanding original micropores; due to PEI-dispersion in mesopores, the CO 2 adsorption capacity for PEI-modied 13X reached 80 mg g À1 at 100 C under a pure CO 2 atmosphere.…”

“…5 Cheng et al incorporated amines into silicas with trimodal pore structures, and the nanocomposite sorbents suggested rapid adsorption kinetics and good adsorption performance, with an adsorption capacity of 172 mg g À1 being obtained for an amine loading amount of 70 wt%. 25 To further improve the dispersion and stability of TEPA or PEI with high viscosity, auxiliary reagents with hydroxyl or ether groups were coloaded into supporting materials for preparing composite sorbents. [41][42][43][44] Jung et al coimpregnated PEI and 1,3-butadienediepoxide (BDDE) with hydroxyl groups in silicas to investigate the improved CO 2 adsorption performance of PEI-loaded silicas, which was primarily attributed to following two aspects.…”

A brief on tetraethylenepentamine (TEPA) functionalized-adsorbents in CO2 capture application

“…Therefore, it could be summarized that a higher partial pressure of CO2 leads to a superior amount of saturated CO2 adsorption. When the concentration of CO2 raised from 5 to 40 vol%, the saturated adsorption capacity of MCF-0.8-TEPA60% was increased (22). This is because when the mixed gases with high concentrations of CO2 pass through the adsorbent, the content of CO2 molecule per unit volume was raised, and thus more CO2 molecules could quickly contact the adsorption sites in the pores.…”

Research progress and applications of silica-based aerogels – a bibliometric analysis

“…Except for humidity, temperature is another influencing factor for CO 2 adsorption. For example, Zhao et al 192 prepared tetraethylenepentamine-functionalized silica foam. When the temperature increased from 30 °C to 75 °C, the CO 2 adsorption ability gradually increased to 4.75 mmol g −1 , which was caused by the improved CO 2 diffusion with the increase of temperature.…”