DRTFTs analysis of CO2 capture using zeolite

https://doi.org/10.1016/j.fuel.2022.123953

“DRIFT subtraction spectra for CO₂ adsorption at 73 and 2 torr (25 °C) on commercial 4A zeolite and sample synthesized from kaolinite at 100 °C and 48 h are plotted in Fig. 7A-C. The spectra were collected after outgassing in situ at 300 °C under He flow for 3 h. In the case of the raw kaolinite, the subtracted spectra show how CO₂ adsorption is negligible, which agree with those data obtained from the CO₂ isotherms at 1 bar and 25 °C (Fig. 5). With regard to the subtracted spectra or synthesized and commercial zeolite, both spectra are very similar between them. After CO₂ dosing (73 torr) appears two bands. The strong band located at 2350 cm⁻¹ is assigned to CO₂ physisorbed (OCO asymmetric stretching). This wavenumber value is higher than that observed for CO₂-gaseous, suggesting that the coordination of the CO₂ molecules with the Lewis sites of the zeolite takes place from the O-atoms of the zeolite so the coordination must generate a linear structure [43].”

“Fig. 7. DRIFT substraction spectra recorded for raw kaolinite (A) zeolite synthesized at 100 °C and 48 h (B) and commercial 4A zeolite after CO₂ adsorption at 20 °C, after outgassing (1 min and 30 min) and after heating at 150, 200 and 300 °C.”