Wadi, BasilGolmakani, AyubManovic, VasilijeNabavi, Seyed Ali2021-11-242021-11-242021-08-30Wadi B, Golmakani A, Manovic V, Nabavi SA. (2021) Evaluation of moderately grafted primary, diamine, and triamine sorbents for CO2 adsorption from ambient air: balancing kinetics and capacity under humid conditions. Industrial and Engineering Chemistry Research, Volume 60, Issue 36, pp. 13309-133170888-5885https://doi.org/10.1021/acs.iecr.1c02416http://dspace.lib.cranfield.ac.uk/handle/1826/17296Successful deployment of direct air capture (DAC) to mitigate the consequences of climate change depends on many factors, one of which is the development of kinetically efficient CO2 sorbents with a high sorption capacity, at ultralow CO2 concentrations. This work evaluated CO2 adsorption performance of primary-, diamine-, and triamine-grafted SBA-15 at pressures below 5 kPa for DAC applications, measured through volumetric sorption, followed by humid air (23% RH) adsorption by gravimetric analysis. Under humid air flow, triamines at an amine loading of 4.6 mmol/g showed the highest enhancement in adsorption, with an uptake of 26 mg/g, but the slowest average adsorption rate of 216 μg/g/min. Diamine at an amine loading of 2.78 mmol/g had an adsorption rate of 295 μg/g/min but demonstrated the lowest uptake of 13 mg/g. In comparison, primary amines at a loading of 2.6 mmol/g reached an equilibrium uptake of 22 mg/g, with a higher adsorption rate of 354 μg/g/min. Triamine grafted at 3.5 mmol/g had the fastest kinetics of all samples, reaching 525 μg/g/min. Results indicated that primary amines and moderate-to-high density triamine reagents incorporated into mesoporous media can offer a superior adsorption rate that can make up for lower adsorption capacities, by optimizing cyclic performance, and should be considered when designing for continuous DAC processes.enAttribution-NonCommercial 4.0 Internationalhttp://creativecommons.org/licenses/by-nc/4.0/Atmospheric chemistryAminesAdsorptionSilicaMaterialsArticle