(728c) Nitrogen-Functionalized Porous Carbons for Enhanced CO2 Capture

Nitrogen-Functionalized Porous Carbons for Enhanced
CO<sub>2</Sub> Capture

Peter C. Psarras, Jiajun He, Jennifer
Wilcox, Energy Resources Engineering, Stanford University, Stanford, CA

Separations Division

"CO2 Capture by Adsorption II: Adsorbents"

The global consequences of
increased anthropogenic carbon dioxide emissions are well documented. To avoid the
catastrophic long-term damages associated with climate change, much attention
has been devoted to the development of CO₂ emission
mitigation strategies. One of the more mature methods involves
CO₂ absorption via amine-based solvents; however, this
technology is notoriously energy intensive, as amine regeneration requires high
regeneration temperatures. Additionally, this process is water-intensive, a
factor that is becoming increasingly important in drought-ridden states like
California. Solid sorbents represent an alternative method for
CO₂ capture, with liquid solvents replaced by
(typically) large surface area, carbon-based porous frameworks. These sorbents
are generally low-cost, easily fabricated, and are far less energy intensive in
terms of regeneration. Further, their design can be customized through the
inclusion of surface-functionalized groups. Unfortunately, current sorbents
display CO₂ uptakes that are deemed too low to be
cost-competitive with traditional solvent-based scrubbing. Nitrogen-functionalization
of these porous carbons could result in more efficient
CO₂ capture, owing to the same chemistry exploited by
basic solvents in capturing acidic CO₂. Similar studies
have examined the effects of oxygenated functional groups on
CO₂ uptake and selectivity over
N₂.

This studt
will employ grand canonical monte carlo
methods to explore the effect of quaternary, pyridinic,
pyrollic, and oxidized-N groups on
CO₂ uptake in porous carbon sorbents. Doping amounts
will be varied to ascertain the optimum coverage for CO₂
capture. Additionally, gaseous mixtures of
CO₂/N₂ and
CO₂/N₂/H₂O
will be examined to assess CO₂ selectivity. Theoretical
performance will be validated through comparison with experimentally obtained CO₂/N₂
isotherms over fabricated hierarchial micro/mesoporous N-doped carbon sorbents. The combination of
these methods will help to inform on sorbent design by illustrating which
groups are most important for enhanced CO₂ uptake. Design
to include more of a particular functional group can be achieved through, for
example, a change in carbonization temperature.