High Adsorption Capacity Fe@13X Zeolite for Direct Air CO2 Capture

The efficient separation of CO2 from air remains an important and challenging goal for direct air capture (DAC). Herein, iron-containing 13X zeolite (Fe@13X) with an efficient separation of CO2 from the air was synthesized via a simple one-step in situ crystallization method. The results demonstrate that Fe@13X exhibited outstanding DAC performance (the CO2 capacity of Fe@13X was 0.64 mmol/g, much higher than the 13X zeolite under simulated air), which was attributed to the introduction of Fe atoms, effectively narrowing the 13X micropore channel. Moreover, the DAC adsorption performance of Fe@13X in the temperature range from 25 to 75 °C was explored by combined thermogravimetric analysis and differential scanning calorimetry. The results revealed that low temperatures were more favorable for the adsorption of CO2 with a high adsorption rate but less selectivity. Furthermore, Fe@13X showed a 3 times higher CO2 production (0.003 kgCO2/kgads·h) and 3.6 times lower desorption energy (0.005 kW h/kgCO2) than 13X zeolite in 400 ppm CO2 in N2. Finally, Fe@13X exhibited excellent cycle stability in simulated air and maintained its initial CO2 uptake in 10 consecutive cycles, showing the broad application prospects of materials in industrial adsorption and separation.