Evaluation of Moderately Grafted Primary, Diamine, and Triamine Sorbents for CO₂ Adsorption from Ambient Air: Balancing Kinetics and Capacity under Humid Conditions

Successful deployment of direct air capture (DAC) to mitigate the consequences climate change depends on many factors, one which is development kinetically efficient CO2 sorbents with a high sorption capacity, at ultralow concentrations. This work evaluated adsorption performance primary-, diamine-, and triamine-grafted SBA-15 pressures below 5 kPa for DAC applications, measured through volumetric sorption, followed by humid (23% RH) gravimetric analysis. Under flow, triamines an amine loading 4.6 mmol/g showed highest enhancement in adsorption, uptake 26 mg/g, but slowest average rate 216 μg/g/min. Diamine 2.78 had 295 μg/g/min demonstrated lowest 13 mg/g. In comparison, primary amines 2.6 reached equilibrium 22 higher 354 Triamine grafted 3.5 fastest kinetics all samples, reaching 525 Results indicated that moderate-to-high density triamine reagents incorporated into mesoporous media can offer superior make up lower capacities, optimizing cyclic performance, should be considered when designing continuous processes.