(371b) Amine-Modified Silica Materials for Direct Carbon Dioxide Capture from the Atmosphere | AIChE

(371b) Amine-Modified Silica Materials for Direct Carbon Dioxide Capture from the Atmosphere

Authors 

Ahmadian Hosseini, A. - Presenter, Florida Atlantic University
Jahandar Lashaki, M., Florida Atlantic University
The objective of this research is to develop adsorbent materials for CO2 capture from ambient air. There is a broad scientific consensus that Greenhouse Gases (GHGs) trap heat in the atmosphere. From 1960 to 2021, the atmospheric concentration of CO2, the most abundant anthropogenic GHG, increased from 320 to 417 parts per million by volume (ppmv). According to NASA, this increase contributed to the 1.1°C increase in global temperature relative to the late 19th century average. In 2018, the Intergovernmental Panel on Climate Change (IPCC) urged a 45% reduction in CO2 emissions by 2030, relative to 2010 levels, to limit global warming to 1.5°C. To curb CO2 emissions, the Blue Map Scenario of the International Energy Agency (IEA) recommends different strategies, including switching to renewable energy sources and implementing CO2 capture technologies. While most CO2 capture efforts have been dedicated to large point sources such as fossil fuel power plants, CO2 capture from the atmosphere, also known as Direct Air Capture (DAC), has been gaining momentum recently. The U.S. Department of Energy recognizes the critical role of DAC in addressing the climate crisis and achieving net-zero emissions by 2050. Owing to their superior performance, DAC applications involving cyclic adsorption-desorption of CO2 by amine-functionalized silica materials (i.e., “aminosilicas”) has attracted tremendous attention from the scientific community and industry alike. However, many relevant studies focus on near-equilibrium CO2 uptake by aminosilicas, while treating adsorbent stability and adsorption kinetics as secondary factors, or totally disregarding them. While aminosilica stability determines its operational lifetime, fast adsorption kinetics is necessary to increase the amount of CO2 captured per unit time. This research aims at taking an innovative approach by prioritizing adsorbent stability and fast adsorption kinetics over adsorption uptake, to develop highly efficient and durable aminosilicas for DAC applications. Aminosilicas were synthesized using (i) a commercially available mesoporous silica (G-10, Fuji Silycia), (ii) four polyamines, namely Tetraethylenepentamine (TEPA) and three branched Polyethylenimines (PEI) with different molecular weights (600, 1200, and 1800), and (iii) five levels of amine loadings (10-50 wt.%). The manipulation of synthesis conditions allowed for achieving a delicate balance between maximizing CO2 uptake, facilitating adsorption kinetics, and maintaining material stability. All materials were evaluated using Thermogravimetric Analysis (TGA) to quantify amine loading, equilibrium CO2 uptake, and CO2 adsorption kinetics in the presence of dry CO2 (400 ppmv, balance nitrogen) over a range of temperatures representing typical Florida conditions (e.g., 25-35°C). The performance of selected performant aminosilicas was assessed in the presence of humid CO2. Finally, the long-term performance stability of the best-performing material was investigated over successive adsorption-desorption cycles.