Porous carbon derived via KOH activation of a hypercrosslinked porous organic polymer for efficient CO2, CH4, H2 adsorptions and high CO2/N2 selectivity (original) (raw)
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Highly porous carbons were prepared by using polyaniline (PANI) as a carbon precursor and KOH as an activating agent via a one-step chemical activation process. The effects of the activation parameters such as activation temperature, KOH–PANI weight ratio and pre-heating temperature were fully investigated, through which the pore structure and the materials chemistry of the activated porous carbons were optimized. When studied as an adsorbent for CO 2 capture, the optimized porous carbon exhibited a high CO 2 capture capacity of 4.50 mmol g À1 , high multi-cycle sorption/desorption stability and highly selective adsorption of CO 2 over N 2 (0.27 mmol g À1) at 25 C. This superior performance for CO 2 capture was found to be closely related to C–H groups on the carbon surface through hydrogen bonding interactions.
Molecules, 2021
In this study, we successfully synthesized two types of meso/microporous carbon materials through the carbonization and potassium hydroxide (KOH) activation for two different kinds of hyper-crosslinked polymers of TPE-CPOP1 and TPE-CPOP2, which were synthesized by using Friedel–Crafts reaction of tetraphenylethene (TPE) monomer with or without cyanuric chloride in the presence of AlCl3 as a catalyst. The resultant porous carbon materials exhibited the high specific area (up to 1100 m2 g−1), total pore volume, good thermal stability, and amorphous character based on thermogravimetric (TGA), N2 adsoprtion/desorption, and powder X-ray diffraction (PXRD) analyses. The as-prepared TPE-CPOP1 after thermal treatment at 800 °C (TPE-CPOP1-800) displayed excellent CO2 uptake performance (1.74 mmol g−1 at 298 K and 3.19 mmol g−1 at 273 K). Furthermore, this material possesses a high specific capacitance of 453 F g−1 at 5 mV s−1 comparable to others porous carbon materials with excellent columb...
Nitrogen-doped porous carbon prepared from a liquid carbon precursor for CO 2 adsorption
We report a new carbonaceous material derived from a liquid precursor, polyethylenimine (PEI) by chemical activation using KOH. The PEI-derived activated carbon possesses typical microporosity with a high specific surface area. It also features rich nitrogen content and various nitrogen functional groups. It was found that at 1 bar the CO 2 uptake of these PEI-derived carbons was 4.9–5.7 mmol g À1 at 0 C and 2.9–3.7 mmol g À1 at 25 C. Specifically, the CO 2 adsorption capacity of the carbon activated at 600 C was the highest, being 5.67 mmol g À1 at 0 C, atmospheric conditions. The PEI-derived carbons also exhibit very good stability during multi-cycle adsorption–desorption tests and a high selectivity of CO 2 over N 2 at 25 C.
ACS Sustainable Chemistry & Engineering, 2018
Selective adsorption of CO 2 from natural gas results in increased calorific value, decreased gas volume, and reduced corrosion. For this purpose, the development of highperformance adsorbents with regard to both adsorption capacity and CO 2 /CH 4 selectivity receives great attention. Herein, two new conjugated microporous polymers (CMPs) were prepared by Yamamoto homo-coupling and Sonogashira-Hagihara cross-coupling reaction. The significant role of homo-and cross-coupling in CMPs in selective CO 2 separation was investigated. Notably, the cross-coupled CMP (NUT-15, NUT means Nanjing Tech University) shows CO 2 uptake around twice than homo-coupled CMP (NUT-14) under the analogous conditions. Furthermore, the importance of KOH-activation and temperature-controlled
Dual-templating-derived porous carbons for low-pressure CO2 capture
Carbon Letters, 2023
Porous carbons are considered promising for CO2 capture due to their high-pressure capture performance, high chemical/ thermal stability, and low humidity sensitivity. But, their low-pressure capture performance, selectivity toward CO2 over N 2 , and adsorption kinetics need further improvement for practical applications. Herein, we report a novel dual-templating strategy based on molten salts (LiBr/KBr) and hydrogen-bonded triazine molecules (melamine-cyanuric acid complex, MCA) to prepare high-performance porous carbon adsorbents for low-pressure CO2. The comprehensive investigations of pore structure, microstructure, and chemical structure, as well as their correlation with CO2 capture performance, reveal that the dual template plays the role of porogen for multi-hierarchical porous structure based on supermicro-/micro-/meso-/ macro-pores and reactant for high N/O insertion into the carbon framework. Furthermore, they exert a synergistic but independent effect on the carbonization procedure of glucose, avoiding the counterbalance between porous structure and hetero-atom insertion. This enables the preferred formation of pyrrolic N/carboxylic acid functional groups and supermicropores of ~ 0.8 nm, while retaining the micro-/meso-/macro-pores (> 1 nm) more than 60% of the total pore volume. As a result, the dual-templated porous carbon adsorbent (MG-Br-600) simultaneously achieves a high CO capture capacity of 3.95 mmol g −1 at 850 Torr and 0 °C, a CO /N 2 (15:85) selectivity factor of 31 at 0 °C, and a high intra-particle diffusivity of 0.23 mmol g −1 min −0.5 without performance degradation over repeated use. With the molecular scale structure tunability and the large-scale production capability, the dual-templating strategy will offer versatile tools for designing high-performance carbon-based adsorbents for CO capture. Keywords CO capture • Porous carbon • Dual template • Multi-hierarchical porous structure • N/O-co-containing carbon
The goal of our research is developing an efficient and cost-effective carbonaceous CO 2 sorbent. Using petroleum coke as the precursor, porous nitrogen-doped carbons were prepared by combining ammoxidation with KOH activation. The as-synthesized samples possess highly developed microporosities and large nitrogen loadings. High CO 2 adsorption capacities of 3.76−4.57 mmol/g at 25 °C and 5.80−6.62 mmol/g at 0 °C under atmospheric pressure were achieved. Specifically, the sample prepared under mild temperature (650 °C) and low KOH/precursor ratio (KOH/precursor = 2) shows a CO 2 uptake of 4.57 mmol/g at 25 °C, among the highest achieved for nitrogen-doped porous carbons. This high CO 2 capture capacity can be attributed to the synergistic effect of nitrogen doping and high narrow microporosity of the sorbent. However, experimental evidence suggests that nitrogen doping contributes less than narrow microporosity. Additionally, the CO 2 /N 2 selectivity and CO 2 heats of adsorption of the sorbent are as high as 22 and 37 kJ/mol, respectively. The sorbent also shows high cyclic stability, fast kinetics, and superior dynamic CO 2 capture capacity under simulated flue gas conditions, thereby demonstrating that it is an excellent candidate for CO 2 capture.
Scientific Reports, 2016
The preparation of nitrogen-doped activated carbon (NACs) has received significant attention because of their applications in CO 2 capture and sequestration (CCS) owing to abundant nitrogen atoms on their surface and controllable pore structures by carefully controlled carbonization. We report high-surfacearea porous N-doped activated carbons (NAC) by using soft-template-assisted self-assembly followed by thermal decomposition and KOH activation. The activation process was carried out under different temperature conditions (600-800 °C) using polyimine as precursor. The NAC-800 was found to have a high specific surface area (1900 m 2 g −1), a desirable micropore size below 1 nm and, more importantly, a large micropore volume (0.98 cm 3 g −1). NAC-800 also exhibits a significant capacity of CO 2 capture i.e., over 6. 25 and 4.87 mmol g −1 at 273 K and 298 K respectively at 1.13 bar, which is one of among the highest values reported for porous carbons so far. Moreover, NAC also shows an excellent separation selectivity for CO 2 over N 2 .
Separations
In this study, the facile and sustainable synthesis of highly microporous carbons is explored to reduce the extensive use of harsh activating agents and solvents. The role of potassium citrate (PC) as a greener activating agent in addition to the conventional ZnCl2 is investigated in the mechanochemical solvent-free preparation of highly microporous carbon materials from chestnut tannin (CT), a biomass-type carbon precursor. A small amount of potassium citrate as a chemical activator coupled with CO2 activation at 700 °C afforded carbons with higher specific surface area (1256 m2 g−1) and larger micropore volume (0.54 cm3 g−1) as compared to the carbons activated with both PC and ZnCl2. The high microporosity of the PC-activated carbon materials, significantly enlarged after CO2 activation from micropore volume of 0.16 to 0.54 cm3 g−1, makes them favorable for CO2 adsorption, as evidenced by high adsorption capacity of 3.55 mmol g−1 at ambient conditions (25 °C, 1 bar). This study s...
Chemical Engineering Journal, 2019
This work reports a selective chemical activation method for the controllable synthesis of porous carbons with pore sizes ranging from micropores to hierarchical micro/mesopores from date sheets. Through selectively controllable carbonization and combined activation processes, the as-prepared carbon materials exhibit a high specific surface area (3337 m 2 /g) mainly derived from ultra-micropores in the range of 0.7-0.9 nm, which majorly contributes to CO 2 storage at a low pressure. Among the activated carbon materials prepared, ACDS-800-4 exhibits the highest CO 2 adsorption capacity (that is, 4.36 mmol/g at 25 o C and 1 bar, and 6.4 mmol/g at 0 o C and 1 bar), a good recyclability and selectivity. ACDS-800-6 exhibits a higher CO 2 adsorption capacity of 22 mmol/g at 25 o C and a high pressure of 40 bar. This work demonstrates that the pore size is key to the CO 2 storage at lower pressures while specific surface area plays an important role under high pressure adsorption process. Since these efficient microporous carbons are synthesized from biomass, this work provides a potential way to develop cost-effective adsorbents for removing CO 2 at both low and high pressures and various temperatures. KEYWORDS: biomass-derived porous carbon; controllable pore size; carbon adsorbents; CO 2 adsorption Highlights Porous carbon prepared from freeze-dried date sheets. Porous carbon exhibits an effective pore size distribution in 0.7-0.9 nm. Porous carbon is used as adsorbents for CO 2 in various temperature and pressure. This work provides a practical way to develop cost-effective adsorbents.
ACS Applied Materials & Interfaces
In this paper, we report the design, synthesis, and characterization of a series of hyper-cross-linked polymers of intrinsic microporosity (PIMs), with high CO 2 uptake and good CO 2 /N 2 and CO 2 /CH 4 selectivity, which makes them competitive for carbon capture and biogas upgrading. The starting hydrocarbon polymers' backbones were functionalized with groups such as −NO 2 , −NH 2 , and −HSO 3 , with the aim of tuning their adsorption selectivity toward CO 2 over nitrogen and methane. This led to a significant improvement in the performance in the potential separation of these gases. All polymers were characterized via Fourier transform infrared (FTIR) spectroscopy and 13 C solid-state NMR to confirm their molecular structures and isothermal gas adsorption to assess their porosity, pore size distribution, and selectivity. The insertion of the functional groups resulted in an overall decrease in the porosity of the starting polymers, which was compensated with an improvement in the final CO 2 uptake and selectivity over the chosen gases. The best uptakes were achieved with the sulfonated polymers, which reached up to 298 mg g −1 (6.77 mmol g −1), whereas the best CO 2 /N 2 selectivities were recorded by the aminated polymers, which reached 26.5. Regarding CH 4 , the most interesting selectivities over CO 2 were also obtained with the aminated PIMs, with values up to 8.6. The reason for the improvements was ascribed to a synergetic contribution of porosity, choice of the functional group, and optimal isosteric heat of adsorption of the materials.