Low temperature synthesized carbon nanotube superstructures with superior CO₂and hydrogen storage capacity

Abstract

Carbon nanotube (CNT) superstructures prepared at 180 °C are activated to highly porous (1479–3802 m2g−1; 0.83–2.98 cm3g−1) carbons with excellent CO2uptake; up to 4.8 and 8.4 mmol g−1at 1 bar and 25 or 0 °C, respectively, and exceptional hydrogen storage; up to 7.5 and 14.9 wt% at −196 °C and 20 or 150 bar, respectively, and 4.4 wt% at 25 °C and 150 bar.

Hyperporous Carbons from Hypercrosslinked Polymers

“…Py800 also shows an extremely high surface area of 4334 m 2 g −1 which, to our knowledge, is the highest reported to date for an organic derived activated carbonaceous material. [12,13,32] The nitrogen isotherms and pore size distributions for the synthesized carbons are shown in Figure S3 temperature was raised to 850 °C, the isotherms display some Type IVa character with a hysteresis loop gradually appearing at P/P 0 = 0.5, this is accompanied by a widening of the pore size distribution ( Figure S3b, Supporting Information) and is due to the formation of mesopores at higher activation temperatures. The higher temperatures led to a decrease in surface area from 3105 m 2 g −1 for Ben750 to 3049 and 2730 m 2 g −1…”

“…Ben750, Th850, and Py800 also show high H 2 uptakes of 4.0, 3.7, and 5.6 wt%, respectively at 10 bar/77.3 K, and all materials reach saturation under these conditions (Figure 3c). These are among the highest H 2 uptakes reported to date for any porous carbon materials at 10 bar, [13,45] and these relatively inexpensive materials outperform zeolite-, [46] carbide-, [47] and MOF-derived carbons. [48] Ben750 and Py800 also outperform the previously reported carbonized N-rich HCP, synthesized from a noncommercial monomer, which adsorbed 2.6 wt% H 2 at 1 bar and 77.3 K. [49] In summary, we have shown that carbonization of HCPs with KOH activation can be used to generate highly porous carbons that show attractive properties for CO 2 and H 2 adsorption.…”

“…Py800, in particular, shows a CO 2 isotherm that is almost linear with pressure. The highest CO 2 uptake at 10 bar was recorded for Py800, which adsorbs up to 22.0 mmol g −1 of CO 2 at 298 K; these are very high CO 2 uptakes in comparison to other leading materials under these conditions, such as MOF-205 (10.9 mmol g −1 ), [41] PPN-4 (11.6 mmol g −1 ), [42] Maxsorb (13.5 mmol g −1 ), [43] CN2800 (13.9 mmol g −1 ), [13] and COF-102 (15.5 mmol g −1 ). [44] Ben750 and Th850 also have high CO 2 uptakes of 15.6 and 13.2 mmol g −1 , respectively.…”

“…[9] Porous carbonaceous materials are traditionally prepared by physical activation, chemical activation, or by a combination of the two. [10] Highly porous carbons have been produced in the past with the use of KOH as a chemical activating agent, through precursors including linear polymers, [11,12] carbon nanotubes, [13] and graphene oxide. [14] A number of microporous solids have been precursors for carbonaceous materials with advanced properties, including zeolitic imidazolate frameworks (ZIFs), [15] metalorganic frameworks (MOFs), [16] porous aromatic frameworks (PAFs), [17] conjugated microporous polymers (CMPs), [18] and hypercrosslinked polymers (HCPs).…”

Templating of carbon in zeolites under pressure: synthesis of pelletized zeolite templated carbons with improved porosity and packing density for superior gas (CO2 and H2) uptake properties

“…[3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] This has included preparation of ultra-high surface area nanostructures for gas uptake at high pressures, 21,22 and on the other hand, synthesis of highly microporous materials for CO2 uptake at low pressure. 7,[33][34][35][36][37][38][39] Unfortunately, at the present time, the materials with the highest surface area generally tend to have low packing density and therefore low volumetric uptake. Enhancements in packing density and consequently volumetric storage capacity of porous materials may be achieved by material densification or compaction.…”