Deactivation Kinetics of Polyethylenimine-based Adsorbents Used for the Capture of Low Concentration CO₂

Abstract

CO 2 emission is generally regarded as the major contributor to global climate change, and polyethylenimine (PEI)-based CO 2 adsorbents are promising materials for the capture of low concentration CO 2 . This paper deals with the deactivation kinetics of PEI-based CO 2 adsorbents used for the capture of low concentration CO 2 . EA and TG analyses demonstrated that thermal degradation and O 2 -induced deactivation of the adsorbents occurred simultaneously under air exposure conditions. It was found by N 2 exposure experiments at the temperature of 50–80 °C that the thermal degradation of PEI-based adsorbents followed a first-order reaction model with an activation energy of 80.98 kJ/mol and a pre-exponential factor of 6.055 × 10 8 (h –1 ). The parallel reaction model was employed to distinguish the O 2 -induced deactivation from the thermal degradation of the adsorbents through air exposure experiments within 50–80 °C. The O 2 -induced deactivation exhibited a second-order reaction with an activation energy of 74.47 kJ/mol and a pre-exponential factor of 6.321 × 10 6 (% –1 ·h –1 ). The results of simulating the overall deactivation of the adsorbents by the parallel reaction kinetic model were well consistent with those of the experiments, proving that the parallel reaction model was feasible for the description of the deactivation of PEI-based adsorbents.

Chemical Kinetics of the Autoxidation of Poly(ethylenimine) in CO2 Sorbents

“…proposed a thermooxidative degradation model for the degradation of PEI as tracked by losses in CO 2 capacity after various oxidation times. The developed model suggested that an O 2 -induced PEI deactivating in simulated air takes on second order kinetics with an activation energy of 74 kJ/mol . This method, however, accounts for the reaction progression based on mass loss, which may not be a comprehensive view due to the complexity of the reactions.…”

Recent advances in direct air capture by adsorption

“…The oxidative stability of PEI-functionalized adsorbents has attracted much research attention. 130,132,254,383,385,390,391,395 Oxidative degradation depends on the operating temperature in addition to the oxygen partial pressure. For example, 55 wt% PEI/SBA-15, as the first PEI-modified adsorbent being reported focusing on the oxidative stability according to our best knowledge, lost 22% and 70% of CO 2 uptake after accelerated oxidative treatment under carbon-free air flow at 90 °C and 100 °C, respectively.…”

Role of Fe Complexes as Initiators in the Oxidative Degradation of Amine Resins for CO2 Capture: Molecular Modeling and Experimental Results Compared

“…The weight loss under a simulated air flow is lower, indicative of the incorporation of oxygen in the material due to oxidative degradation. The loss of CO 2 capacity at 50 °C under thermal and oxidative degradation conditions after ∼2700 h is 2.0 and 3.6% respectively, while the weight loss is 1.0 and 1.2% respectively (Figure 3 26 ). The curves of thermal and oxidative degradations over time do not show a distinctive shape.…”

“…Si et al reported on simulated air oxidation of BPEI in the total absence of H 2 O and CO 2 . Reaction times were up to 3000 h, and a temperature window from 50 to 80 °C was used …”