TEPA functionalized adsorbents dominated by pore type and pore size: Direct air capture characteristics and economic efficiency optimization

Direct air capture (DAC) technology is a key pathway to achieving carbon neutrality, but its commercialization remains constrained by the high cost of adsorbents and the synergistic effect between pore structure and amine utilization. This study investigates the influence of carrier pore size and pore type on carbon dioxide adsorption and the economic feasibility of DAC technology for industrial applications. We loaded tetraethylenepentamine (TEPA) onto three carriers via physical impregnation: activated carbon (AC), Mobil Composition of Matter-41 ‌(MCM-41), and Santa Barbara Amorphous-15 (SBA-15), which differ in cost and pore structure characteristics. The results showed that the AC adsorbent had an adsorption capacity of 1.25 mmol/g at 70 % TEPA loading. The MCM-41 and SBA-15 adsorbents exhibited higher adsorption capacities at a 60 % TEPA loading, with values of 1.94 mmol/g and 2.61 mmol/g, respectively. The costs of the three adsorbents were 30$/kg, 150$/kg, and 700$/kg, respectively. Comparing different capture modes, the annual CO 2 capture capacity of 60-TEPA/MCM-41 and 60-TEPA/SBA-15 in the quick capture mode is 1.58 times and 2.11 times higher than that in the complete capture mode, respectively. However, the annual capture capacity of 70-TEPA/AC is slightly lower in the quick capture mode. Further analysis revealed that, based on the quick capture mode, the overall cost of 60-TEPA/MCM-41 was 472$/tCO 2 , achieving a balance between capture performance and cost-effectiveness.