Tunable Polyaniline‐Based Porous Carbon with Ultrahigh Surface Area for CO₂ Capture at Elevated Pressure

Abstract

However, natural gas wells contain considerable amounts of CO 2 (i.e., typically 10-20 mol% and as high as 70 mol% in some locations), [2] which require on-site CO 2 capture. Amine scrubbing has been used previously for CO 2 removal from natural gas, but its drawbacks are prominent, some of which include the corrosive nature of the amine solution, significant energy penalty associated with material regeneration, and difficulty in the implementation of off-shore capture units. [3,4] The development of novel materials and technologies for CO 2 capture has attracted tremendous interest from the scientific community, while solid sorbent technologies have shown great promise. [5,6] Among the broader class of solid sorbents, porous carbons are of particular interest due to their exceptional chemical and physical stability, high surface area, and flexibility in terms of tunable pore structure and surface functionality. [7][8][9] However, it is still challenging to improve the CO 2 capacity at high pressures relevant to natural gas purification. An interesting strategy of heteroatom-induced CO 2 polymerization has been explored; [10] however, it has shown relatively low CO 2 capacity at elevated pressures compared to some commercial activated carbons. [11] Another attractive approach is to optimize the pore properties including surface area, pore volume, and pore size; [12] however, the synthesis of these high-surface area carbons involves the use of sacrificial templates of metalorganic frameworks (MOFs), which adds complexity and increases material cost.In our recent work, we reported a low-cost and templatefree synthesis of a highly porous 3D carbon with superior performance for energy storage applications. [7] Herein, we extend the synthetic approach with efficient tunability on the surface area and pore size distribution (PSD). Our strategy is based upon the thermal annealing of a 3D hierarchical nanostructured polymer hydrogel (polyaniline, or PANi) without any sacrificial templates, followed by chemical activation. The surface area and pore size distribution can be tuned simply by varying the carbonization temperature. The final porous carbon (denoted as SU-AC) materials have ultrahigh surface areas up to 4196 m 2 g −1 and total pore volume as large as 2.26 cm 3 g −1 . More importantly, the SU-AC materials have abundant microand narrow mesopores (d < 4 nm) up to 2.03 cm 3 g −1 (≈90% of the total pore volume), which are beneficial for CO 2 adsorption Natural gas is the cleanest fossil fuel source. However, natural gas wells typically contain considerable amounts of CO 2 , with on-site CO 2 capture necessary. Solid sorbents are advantageous over traditional amine scrubbing due to their relatively low regeneration energies and non-corrosive nature. However, it remains a challenge to improve the sorbent's CO 2 capacity at elevated pressures relevant to natural gas purification. Here, the synthesis of porous carbons derived from a 3D hierarchical nanostructured polymer hydrogel, with simple and effective tunability ove...

Ultra‐High Surface Area Nitrogen‐Doped Carbon Aerogels Derived From a Schiff‐Base Porous Organic Polymer Aerogel for CO2 Storage and Supercapacitors

“…As mentioned before, NCA‐900 indeed exhibits a maximal capacity of ≈6.1 mmol g −1 at ambient pressure, thus representing a promising material for this application. Notably, NCA‐900 exhibits a record‐high CO 2 uptake capacity among reported carbons at high pressure, i.e., 145.6 wt% (33.1 mmol g −1 ) at 323 K and 30 bar (Figure S4, Supporting Information), which exceeds that of the best‐performing literature carbon SU‐AC‐400 (28.3 mmol g −1 ) under close conditions (298 K and 30 bar) possibly owing to the much higher nitrogen content (3.32 vs 0.55%) . Considering the sample density (5 mg cm −3 ), the volumetric efficiency of NCA‐900 for CO 2 uptake is calculated to be 0.1655 mmol cm −3 , i.e., 7.282 mg per cc.…”

Agar‐Derived Nitrogen‐Doped Porous Carbon for CO2 Adsorption

“…For carbon materials, this uncommon trend was ascribed to strong interactions between the adsorbed CO 2 molecules . Under low pressure conditions, the density of the adsorbed CO 2 in ultramicropores is higher than that in the large micropores, which favors a stronger gas‐gas interaction . This should also be the reason why Q st only increases for carbons with the most ulramicropores in Figure .…”

Porous Carbons: Structure‐Oriented Design and Versatile Applications

“…[ 39b,41 ] Impressively, light‐weight porous carbons are widely viewed as advantageous sorbents, because of their remarkable stability, structural flexibility, sustainability, low costs, excellent recycling performances, and low regeneration energy. [ 39b,42 ] Some factors that govern the behavior of porous carbons in the post‐ or pre‐combustion carbon capture are presented in Figure and discussed below.…”