Low-Temperature and Single-Step Synthesis of N-Doped Porous Carbons with a High CO₂ Adsorption Performance by Sodium Amide Activation

Abstract

In this study, N-enriched porous carbons were prepared by a facile synthesis method at low temperatures ranging from 400 to 500 °C. Sodium amide was used as both activator and nitridation reagent, and lotus stalk was used as the carbon precursor. The as-synthesized samples demonstrate the maximum CO2 uptake of 3.88 and 5.62 mmol/g at 25 and 0 °C, respectively, at atmospheric pressure. Moreover, these lotus stalk-derived adsorbents exhibit a rapid CO2 adsorption rate, high CO2/N2 selectivity, moderate CO2 isosteric heat of adsorption, stable cyclic ability, and excellent dynamic CO2 capture capacity. Systematic research shows that, besides the volume of narrow micropore and nitrogen content, the pore size distribution is also a non-negligible factor in determining CO2 adsorption capacity under ambient condition for these adsorbents. The good CO2 adsorption performance together with single-step and low-temperature preparation indicates that these sorbents are very promising for CO2 capture from flue gas.

Sustainable Biomass Glucose-Derived Porous Carbon Spheres with High Nitrogen Doping: As a Promising Adsorbent for CO2/CH4/N2 Adsorptive Separation

“…The presence of N can not only provide Lewis basic active sites, but also increase the carbon framework polarity, which is beneficial for CO 2 /CH 4 /N 2 selectivity adsorption [21,23,35,37]. It should be stressed that N-5 was the main type of N species in the carbons, which is beneficial to boosting the CO 2 capture [21,35,60]. Moreover, the high-resolution spectra of C1s ( Figure S1a boosting the CO2 capture [21,35,60].…”

“…As shown in Figure 5c, d and e, three sub-peaks are visible in the deconvoluted XPS N1s spectra: Pyridinic-N (N-6) at 398.5 eV, pyrrolic-/pyridonic-N (N-5) at 399.9 eV, and pyridine-N-oxide (N-X) at 402 eV, respectively [21,30,58,39]. The presence of N can not only provide Lewis basic active sites, but also increase the carbon framework polarity, which is beneficial for CO2/CH4/N2 selectivity adsorption [21,23,35,37]. It should be stressed that N-5 was the main type of N species in the carbons, which is beneficial to a Specific surface area calculated by Brunauer−Emmett−Teller (BET) method; b total pore volume obtained at P/P 0 0.99; c cumulative pore volume calculated in the range of pore widths up to 2 nm; d cumulative pore volume calculated in the range of pore widths up to 1 nm; e obtained from C, H, and N elemental analysis; f calculated by difference.…”

“…As shown in Figure 5c-e, three sub-peaks are visible in the deconvoluted XPS N1s spectra: Pyridinic-N (N-6) at 398.5 eV, pyrrolic-/pyridonic-N (N-5) at 399.9 eV, and pyridine-N-oxide (N-X) at 402 eV, respectively [21,30,39,58]. The presence of N can not only provide Lewis basic active sites, but also increase the carbon framework polarity, which is beneficial for CO 2 /CH 4 /N 2 selectivity adsorption [21,23,35,37]. It should be stressed that N-5 was the main type of N species in the carbons, which is beneficial to boosting the CO 2 capture [21,35,60].…”

“…In other words, previous works have indicated that biomass-derived porous carbons are promising adsorbents for CO 2 /CH 4 /N 2 adsorption and separation. Nevertheless, the preparation of biomass-derived porous carbons for gas-selective adsorption usually uses the harsh activator KOH, which is undesirable due to its strong inherent causticity, causing equipment corrosion and damage [35,36]. Thus, it is crucial to use a mild activation reagent of environmentally friendly nature for further development of gas-selective separation applications.…”

One‐pot synthesis of high N‐doped porous carbons derived from a N‐rich oil palm biomass residue in low temperature for CO 2 capture

“…In some previous studies, sodium amide (NaNH 2 ) was found to be both an activator and a nitrogen source. [22][23][24] Compared with potassium hydroxide (KOH), using NaNH 2 as an activator, is less corrosive to the equipment. At the same time, the activation temperature was lower (T < 600 C).…”