Carbon Dioxide Adsorption on Amine-Impregnated Mesoporous SBA-15 Sorbents: Experimental and Kinetics Study

Abstract

In this work, an experimental and theoretical investigation was conducted on the adsorptive removal of CO 2 onto tetraethylenepentamine (TEPA) functionalized mesoporous SBA-15. The functionalization of SBA-15 silica with TEPA was achieved using a conventional wet impregnation technique. The structural properties of the mesoporous silica sorbents were characterized by nitrogen adsorption/desorption, SAXS, SEM, TEM, and FTIR techniques. The adsorption of CO 2 on the amine-impregnated sorbent was measured by thermogravimetric method over a CO 2 partial pressure range of 10−100 kPa and a temperature range of 30−100 °C under atmospheric pressure. The effects on CO 2 adsorption capacity of temperature, partial pressure of CO 2 , amine loading, and moisture were evaluated. All the impregnated SBA-15 sorbents showed reversible CO 2 adsorption behaviors with fast adsorption kinetics. The CO 2 adsorption capacity measured at different temperatures suggests that the optimal adsorption temperature is 75 °C. The CO 2 uptake of the amine-impregnated sorbent increased significantly in the presence of moisture. SBA-15 containing 60 wt % TEPA showed the highest CO 2 adsorption capacity of 5.22 mmol/g in pure and humid CO 2 at 75 °C. Temperature swing adsorption/desorption cycles were also explored using simulated flue gas in both dry and humid conditions, and it was found that CO 2 uptake after ten cycles was within 90% of CO 2 uptake of the first cycle. Different adsorption kinetic models have also been investigated to analyze the experimental data of CO 2 uptake. The model was validated with the experimental results of isothermal adsorption measurements of CO 2 on SBA-15/TEPA. It has been found that Fractional Order kinetic model (Chem. Eng. J. 2011, 173, 72) is very good over the entire adsorption region of the study with a maximum average absolute deviation between experimental CO 2 uptake and that calculated from the model of about 2.42%.

Tailoring amine functionalized hybrid ceramics to control CO2 adsorption

“…In more detail, the effect was discussed to be due to a low diffusivity of CO 2 at low temperatures, which limits diffusion to amine sides of low accessibility. Moreover slow reaction kinetics for amine -CO 2 interaction at low temperatures might be responsible for increasing CO 2 sorption capacities with the temperature [53]. The same effect was observed for adsorber materials grafted with amines.…”

“…However, in several cases of physically attached amines the CO 2 sorption capacity was observed to increase with the temperature up to an optimum of about 75 °C [52,53]. This indicates that not all possible sorption sites can contribute to the sorption capacity at low temperatures but CO 2 sorption sites of strong interactions are available for sorption at higher temperatures.…”

“…For APTES 200 p350 the value could even be increased during pyrolysis, compared to the nonpyrolyzed material (0.9 mmol g -1 ), indicating that either hydrophilicity was lowered or the pore size increased and therefore the diffusion limitation reduced. CO 2 sorption capacities as high as 4.9 mmol g -1 at 75 °C or even 5.2 mmol g -1 under humid conditions were observed in the case of impregnation of mesoporous carbon or silica particles with amines like polyethylenimine or tetraethylenepentamine [52,53]. However, despite the knowledge that higher CO 2 sorption capacities can be achieved by impregnation with amines, the leakage of physically attached amines is expected to be higher during application [15,54].…”

Investigation of Acid Blue 62 Dye Adsorption using SBA-15/Polyaniline Mesoporous Nanocomposite: Kinetic and Thermodynamic Study

“…The SBA-15, a family of highly arranged mesoporous silica compounds, has attracted the great interest (to be modified and functionalized) due to its large mesopore volume, high surface area, thicker pore walls (3.1−6.4 nm), high thermal , hydrothermal stability, tailorable large offered pores from 4.6-30 nm, and slim distribution of pore size in comparison to other mesoporous silica structures (30). In addition, it reveals the presence of micropores that are in control into the pore boundaries and also intraconnectivity in the channels of adjacent mesopore by micropores and slim mesopores.…”

“…This non-stop network helps diffusion into the whole SBA-15 porous structure during adsorbing process. Therefore, it is vital to discover SBA-15 designation and modification support for high dyes adsorption capacity, especially higher than room temperature, by functionalization of amine (30). The amine group plays a key role in determining the medicated silica mesoporous adsorbents performance.…”