Low-cost preferential different amine grafted silica spheres adsorbents for DAC CO2 removal

DAC CO2 capture is gaining wide attention as one of the most difficult carbon approaches to tackle climate change. In this work, different pore-size silica spheres were grafted using different amine groups such as APTES, APTMS, and Diamine. Herein, all samples based on the wet and dry grafting method were used for CO2 adsorption isotherm at room temperature and pressure (298 K and 1 bar). The sample based on the wet grafting (Silica-APTES-W) sample shows the highest CO2 uptake 1.67 mmol/g. Also, the adsorption isotherm of the Silica-APTES-W sample was showed a high capacity of CO2 1.2 mmol/g at 25 °C, which describes the strong physical interaction between CO2 and amine. The isosteric adsorption of Silica-APTES-W also confirmed that the physical adsorption was dominant because of low adsorption heat ranging from 23 to 37 kJ/mol. Also, the fixed bed experiment was conducted with 2000 ppm CO2 that obtains the optimal working capacity 4.5 mL/g with the lowest regeneration temperature 90 °C. It was shown that Silica-APTES-W sample was superior performance for DAC CO2 capture in practical applications.