https://doi.org/10.1016/j.apenergy.2016.09.081
“Fig. 6 shows the adsorption kinetics of CO2 onto silica gel before and after its impregnation with different DETA loadings measured at 25 °C. It can be observed that CO2 adsorption displays two different stages. Once the sorbents were exposed to the pure CO2 stream (60 mL/min), a sharp weight gain occurred in less than 1 min, in which impregnated samples reached around 70% of their capacity. This fast process is then followed by a much slower adsorption process over the remaining 249 min in which the CO2 uptake increased to the maximum observed (Fig. 7). This two-stage adsorption process showed similar trends in all the amine impregnated samples. For FS, CO2 adsorption reached the maximum quickly, and the second stage was not obvious. The adsorption kinetics of samples prepared in this work, i.e. FS-DETA-10%, which reached 70% of its capacity after 47 s, is comparable with that reported for some other adsorbents in literature (i.e. KIT-6 impregnated with 50% PEI reached 70% of its capacity after 1 min [16]), but it is several times faster than many others, like the impregnated MCM-41-PEI-50%, which reached 70% of its capacity after 5.7 min [16], [26], [35], [51], or the surfactant-promoted hierarchical porous silica (HPS) monoliths which completed the first stage in about 5 min [52]. Table 4 summarises the time taken to reach 50%, 70%, 80% and 90% of the maximum adsorption capacity for the most common PEI-loaded (50 wt.%) support materials, and the materials prepared in this work. Table 3 shows the time required for the regeneration of CO2 in DETA-FS samples by flushing a N2 stream at 60 °C. The 80% of the CO2 was desorbed after 8–9 min flushing N2 on FS-DETA-10%.”
“Fig. 6. Experimental CO2 adsorption profiles of FS silica gel before and after the impregnation with DETA at different loadings. Conditions: 25 °C and 1 bar.”
“Fig. 7. CO2 capture capacity of the low cost amorphous micro-mesoporous silica gel, before and after the impregnation with DETA at different loadings. Adsorption time effects on CO2 capture capacity.”