(425a) Role of Support Structure in Developing Amine Grafted Adsorbent for Direct Air Capture

The global anthropogenic CO₂ emissions have reached 37 Gigatons (Gt), resulting in the increase of atmospheric CO₂ concentrations to 420 parts per million (ppm). Some engineered solutions to remove CO2 from the atmosphere use adsorbents that have a high CO₂ capacity in the presence of water vapour. Aminated or amine functionalized materials are one class of materials that meet these requirements. While, there has been an increase in the synthesis of amine-based materials, the understanding behind selection of the support is less explored. In the present study, 3-aminopropyl-methyl-diethoxysilane (APDES) is used to as a functionalizing agent. We study two different support materials that offer reactive sites for silane bonding. The preliminary morphological studies reveal that the selected supports have two different particle sizes. The S₁has a particle size ranging between 10 – 20 mm and S₂ has a particle size less than 2 mm. Thermogravimetric analysis (TGA) to determine the amount of amine content from the weight loss values. Mostly, this was used as a qualitative check to match the N content (mmol/g) values obtained from the CHN analysis. Simultaneously, N₂, CO₂ and H₂O adsorption capacities of the pristine materials and the functionalized materials were measured. The uptakes of CO₂ adsorption were also obtained from TGA studies. These experiments provided an option to explore the tether coverage to amine loadings. It also helps in understanding the influence of humidity on the binary adsorption of CO₂ and H₂O for a given amine loading. Besides determining the lumped mass transfer coefficient, the study also discusses the process implications of the chosen support.