Efficient and stable carbon capture from industrial flue gas under humid conditions using amine-functionalized...

Amine functionalization is a well-known approach to enhance CO₂ adsorption capacity in metal-organic frameworks (MOFs), especially in humid environments. In this study, triethylenetetramine (TETA) was used to functionalize Zr-MOF-808 via wet impregnation, and its CO₂ adsorption studies were performed using wet flue gas. To conduct the adsorption tests, a simulated industrial flue gas mixture was used, containing 12 vol% CO₂, 10 vol% H₂O, 8 vol% O₂, with the remainder being N₂. To systematically investigate the effects of various parameters on CO₂ adsorption and identify optimal operating conditions, response surface methodology (RSM) combined with a central composite design (CCD) was employed. Under optimal conditions 55 °C temperature, 20 wt% TETA loading, 3 g of adsorbent, and 180 minutes of carbonation time, the model estimated an adsorption capacity of 3.6 mmol g^-1, which is very close to the maximum experimental adsorption capacity of 3.4 mmol g^-1. The RSM-CCD analysis indicated that both carbonation time and temperature significantly influence the results, while amine loading has a notable quadratic effect. The Avrami model provided the best fit for the kinetic behaviour, whereas the Sips isotherm most accurately described the isotherm behaviour. Moreover, Zr-MOF-808-TETA (20%) retained 88% of its original capacity after 10 consecutive cycles. Therefore, the results indicate that TETA-functionalized Zr-MOF-808 is a potential candidate for CO₂ capture under humid simulated flue gas conditions.