A Study of CO ₂ Adsorption of MEA-Modified Zeolite 13X and K ₂ CO ₃ -Impregnated Alumina for Direct Air Capture

High Resolution Image Download MS PowerPoint Slide Rising industrial CO 2 emissions have created an urgent need for efficient carbon capture and storage (CCS) technologies. This study compares the CO 2 adsorption performance of three sorbents, namely zeolite 13X (Z13), monoethanolamine-modified zeolite (Z13/MEA), and K 2 CO 3 -impregnated alumina (K 2 CO 3 /Al 2 O 3 ), under realistic direct air capture (DAC) conditions (∼450 ppm of CO 2, RH 60–65%, 26 ± 2 °C). The sorbents were prepared by wet impregnation with actual loadings of 6.98 wt % MEA (CHNS) and 4.01 wt % K 2 CO 3 (XRF), and were characterized by BET, CHNS, XRF, SEM, XRD, FTIR, and TGA. Z13/MEA exhibited the highest uptake (∼40 mgCO 2 /g), substantially greater than pristine Z13 (12 mg/g) and K 2 CO 3 /Al 2 O 3 (5 mg/g). Under the humid DAC pathway (1:1 bicarbonate stoichiometry), these values correspond to 79% amine and 39% carbonate utilization, respectively. The superior performance of Z13/MEA is attributed to chemisorption at the −NH 2 sites, confirmed by FTIR bands at 1650 cm –1 (carbamate) and 1380 cm –1 (bicarbonate) and an increase in carbon content from 3.4% to 3.8% after use. Pore blocking by MEA reduced the specific surface area from 502 to 25 m 2 /g but partially recovered to 262 m 2 /g after regeneration. XRD results confirmed the zeolite framework remained intact. Z13/MEA retained ≥90% of its initial capacity over 10 cycles under mild TSA regeneration at 80 °C, indicating good cyclic stability and low regeneration-energy demand. These findings provide a comparative basis for designing durable sorbents for CCS technology toward Net-Zero goals.