The current study reports the utilization of tetraethylenepentamine
(TEPA)-modified hierarchical silica particles having bimodal meso/macroporosity
for CO2 capture under simulated direct air capture (DAC)
conditions (400 ppm CO2 in He). Results infer a typical
relation between TEPA loading and CO2 capture, where TEPA-impregnated
HS (HS-TEPA-70) exhibits exceptionally high CO2 uptake
(5.20 mmol/g), shorter adsorption half time (110 min), and excellent
amine efficiency (0.32 mmol of CO2/mmol of N) with moderate
CO2/N2 selectivity at 30 °C under DAC conditions.
HS-TEPA-70 also showed appreciable CO2 adsorption performance
(5.88 mmol/g) under humid conditions (50 ± 3% RH) with 400 ppm
CO2 in He at 30 °C. TEPA-impregnated HS even displays
better thermal stability up to 10 consecutive adsorption–desorption
cycles with minimal amine leaching and moderate CO2 regeneration
energy. Moreover, the pelletized form of HS-TEPA-70 also demonstrates
better CO2 adsorption performance (3.34 mmol/g), which
makes it a promising candidate for CO2 capture from ambient
air by temperature swing adsorption.
Direct Air Capture (DAC) emerges as a new technology that can contribute to “negative carbon emission.” Recent progress in surface chemistry and material synthesis has allowed a new generation of...
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