Highly aminated carbon paper for CO2 capture

• Highly filled papers, composed of 80% AC and 20% CNFs, were fabricated and aminated. • The aminated carbon paper had high CO 2 uptake of 0.46 mmol/g at 400 ppm CO 2 . • The paper sheets arranged in channel structures exhibited a 7.5 times lower pressure drop than loose-fill bed at 1.43 m/s. • The aminated carbon paper demonstrated a high potential for DAC application. Packed-bed CO 2 capture system often suffer from high pressure drops, limiting scalability and efficiency. To address this limitation, we developed an aminated, highly filled paper adsorbent designed for a structured configuration with low pressure drop. Four commercial activated carbons (ACs) were first screened as paper fillers based on their low-pressure CO 2 uptake at 20°C, identifying DARCO® activated charcoal (AC-DC) as the optimal candidate. Paper sorbents were fabricated using 80 wt.% AC-DC as filler and 20 wt.% cellulose nanofibrils as binder, followed by polyethyleneimine (PEI) amination. Two amination routes were compared: i) post-impregnation of pristine AC paper (post-PEI-AC paper) and (ii) papermaking from pre-aminated AC-DC (pre-PEI-AC paper). The former remarkedly outperformed the latter, achieving a static CO 2 uptake of 0.46 mmol/g at p CO2 = 0.04 kPa (400 ppm) and 20°C, which decreased by 58% at 50°C but increased by 77% at 100 kPa. When structured into alternating flat–corrugated stacks to form channel-like pathways, the post-PEI-AC paper exhibited a 7.5-fold lower pressure drop than loose-fill beds at a superficial velocity of 1.43 m/s. This advantage is expected to grow at higher velocities as packed beds followed a superlinear pressure drops-velocity dependence, contrasting with the linear trend for the paper adsorbents under laminar flow. These findings demonstrate the feasibility and potential of aminated, highly filled paper adsorbents for efficient CO 2 capture. The structured design combines high sorbent productivity with low pressure drop, offering a promising and scalable pathway toward energy-efficient direct air capture technologies.