Increasing CO
2 content in the atmosphere has led to a significant interest in amine-containing solid sorbents with high CO
2 sorption capacity for economically viable direct air capture (DAC) of CO
2. Current challenges for DAC technologies are low CO
2 partial pressure, high energy requirement, and thermal stability of the material during regeneration. This work focuses on developing and studying next-generational sorbent material which can help in overcoming these challenges. In this study we synthesize green sorbent-support based materials comprising of biodegradable cellulose-aerogel based substrate with high porosity (~60%) and surface area (~500 m2/g), impregnated with PEI using wet impregnation method. PEI is impregnated inside the pores of the substrate, and the porosity and surface area of the developed adsorbents were easily manipulated by adjusting the PEI content in the coating solution. These amine-based adsorbents were tested under varying environmental conditions to study the effect of parameters like temperature, humidity and CO
2 concentration in the feed on sorption capacity of the material. The cyclic stability of the material was also tested. 30%PEI loaded sample (AG/C-PEI30) showed the best performance over varying temperature range. A maximum CO
2 capacity of 0.26 mmol/g was obtained with 30% loading of PEI25k at 25oC, and introducing 50% relative humidity at 35oC increased CO
2 sorption capacity by ~56%. Exposing material to a long-term stability test of 10 adsorption-desorption cycles showed good cyclic stability and regeneration capacity. This work highlights green biodegradable based porous substrate which offers a sustainable and low-cost alternative with competitive performance, and exploring development of more sustainable, cost-effective, and durable future DAC materials.
Keywords: Direct air capture (DAC), adsorbents, polyethyleneimine (PEI), Aerogel/cellulose substrate
