Functionalized SBA-15 for CO2 capture and influence of temperature

https://doi.org/10.3390/en13215804

“The amine loading density (ρ_N) of functionalized silica SBA-15, which includes the quantities of impregnated and grafted amine, is an essential parameter for evaluating the CO₂ adsorption capacity. Table 4 shows the amine loading density for the obtained samples calculated using the mass percentage of nitrogen from the elemental analysis (see Table 2). Samples functionalized in scCO₂ modified with alcohol exhibited amine loads that ranged from 1.3 to 3.8 mmol N∙g^–1, which are close to those published in the literature using toluene as a solvent [32,39].”

“The excess CO₂ adsorption capacities of the amine-functionalized samples and bare silica at atmospheric pressure and various temperatures are shown in Table 4 and Figure 6. The adsorption capacity was defined as the ratio of adsorbed CO₂ mol and sample mass (mmol CO₂∙g⁻¹ sample). The amine efficiency was calculated by dividing the amount of CO₂ adsorbed and the amine loading quantity (mol CO₂∙mol N⁻¹). This quantity is a useful instrument for comparing adsorbents. Table 3 reports the amine efficiencies at 298 and 333 K, as typical temperatures for direct air capture and post-combustion capture, respectively.”

“Figure 6. Excess CO₂ adsorption capacity for several amine loadings; ρ_N at eight temperatures for samples obtained by scCO₂ method (a,b) and toluene method (c). (a) Amine loading up to 3 mmol N∙g⁻¹ at temperatures of ●, 298; ●, 313; ●, 333; ●, 353; ●, 373; and ●, 433 K. (b) Amine loading: ●, 3.8, and, ●, 3.2 mmol N∙g⁻¹. (c) Amine loading: ●, 5.0, and ●, 4.4 mmol N∙g⁻¹.”