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In the current work, we presented the synthesis of N-doped hierarchically porous carbons (NDHPCs) through chemical activation of hierarchically structured precursor derived from polyvinylpyrrolidone (PVP) and magnesium acetate tetrahydrate. Magnesium acetate tetrahydrate served as the blowing agent, and its decomposition product MgO served as the in-situ formed hard template. Combined with KHCO 3 activation, the NDHPCs demonstrated a unique micro- meso -macroporous structure. Owing to the highly porous structure (1560–2545 m2/g) and enriched N-doping (1.48–6.31 wt%), the NDHPCs were investigated as potential CO 2 adsorbents in both post-combustion capture and pre-combustion capture applications. When the adsorption temperature was 25 °C, the samples showed outstanding capture performances at both 1 bar (2.97–3.88 mmol/g) and 20 bar (13.24–19.89 mmol/g). The adsorption performances were further analyzed with grand canonical Monte Carlo (GCMC) simulation. Effects of various physicochemical properties on CO 2 adsorption at different pressures were thus revealed with a combined experimental-theoretical approach. [Display omitted] • NDHPCs with unique micro- meso -macroporous structure are prepared. • The precursor is prepared through chemical blowing and in-situ hard template. • The NDHPCs demonstrate high S BET (1560–2545 m2/g) and N content (1.48–6.31 wt%). • At 25 °C and 20 bar, CO 2 uptake of the NDHPCs reaches 19.89 mmol/g. [ABSTRACT FROM AUTHOR]

In the present study, N-doped hollow carbon nanospheres (NHCNs) were synthesized with a combined soft template-chemical activation method. Spherical hollow hydrochar was prepared from glucose with the assistance of dual soft templates, and was then chemically activated with KHCO 3 and urea to produce the NHCNs. Effects of urea addition and activation temperature on the NHCNs' physicochemical properties were revealed. The NHCNs were endowed with rich N-doping and developed porosity. The sample activated at 800 °C (NHCN2800) showed an impressive specific surface area of 3234 m2/g. The proposed method could also be extended to the synthesis of N, S co-doped hollow carbon nanospheres. We then investigated CO 2 adsorption performances of the NHCNs. At 25 °C and 1 bar, the best CO 2 uptake of the NHCNs was 4.36 mmol/g; at 20 bar, it increased to a record high level of 23.62 mmol/g. Correlations between textural characteristics/N-doping and CO 2 adsorption at 1/20 bar were analyzed and discussed. The current study indicated that the obtained NHCNs had great potential for applications in both pre- and post-combustion CO 2 capture. [Display omitted] • NHCNs are prepared with a combined soft template-chemical activation method. • The NHCNs demonstrate well-defined hollow spherical structure. • The NHCNs exhibit ultrahigh S BET up to 3234 m2/g. • At 25 °C and 20 bar, CO2 uptake of the NHCNs reaches 23.62 mmol/g. [ABSTRACT FROM AUTHOR]

The preparation and application of heteroatom doped carbons have attracted lots of attention in the past years. In the current work, a facile synthesis of nitrogen doped carbon with filter paper as the carbon source and urea as the nitrogen source was presented. Filter paper was first impregnated with urea solution, and was then carbonized and activated. The carbons' physical and chemical properties were studied. For the application in CO 2 adsorption, impacts from porous characteristics and nitrogen doping were discussed and differentiated. The results suggested that nitrogen doping was beneficial to the improvement of CO 2 uptake, but suitable porous properties were the most important factors. Nitrogen doping showed more significant effects on enhancing the adsorption heat and selectivity. The research of carbonaceous CO 2 adsorbent should focus on nitrogen doped carbons with high porosity. • Urea loaded filter paper is used as starting material for nitrogen doped carbon. • Effects of nitrogen doping and porous structure on CO 2 adsorption are studied. • CO 2 uptake at 273 K and 1 bar reaches 5.12 mmol/g. • Nitrogen doping has obvious effects on CO 2 adsorption heat and selectivity. [ABSTRACT FROM AUTHOR]