Abstract
The preparation of nitrogen-doped activated carbon (NACs) has received significant attention because of their applications in CO2 capture and sequestration (CCS) owing to abundant nitrogen atoms on their surface and controllable pore structures by carefully controlled carbonization. We report high-surface-area 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 m2 g−1), a desirable micropore size below 1 nm and, more importantly, a large micropore volume (0.98 cm3 g−1). NAC-800 also exhibits a significant capacity of CO2 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 CO2 over N2.
Highlights
Over the past decades, a variety of solid-based microporous materials have been used for CO2 capture and storage such as metal organic frameworks (MOFs), hyper-crosslinking polymer (HCPs), covalent organic frameworks (COFs), activated carbons (ACs), functionalized graphene, chemically modified mesoporous materials, and so forth[5,6]
We present a facile strategy, which involves a new type of polyimine direct pyrolysis with KOH as a chemical activating agent in the tubular furnace by adjusting the activation temperature, to prepare (i) highly ordered N-doped porous activated carbon using polyimine as an organic precursor (ii) naturally occurring nitrogen is preserved as dopants to motivate molecular adsorption, e.g. for CO2 capture
The amount of CO2 adsorbed by N-doped activated carbons (NAC)-800 is comparable to that of NAC-700 and NAC-600, indicating that NAC-800 has a greater affinity towards CO2
Summary
A variety of solid-based microporous materials have been used for CO2 capture and storage such as metal organic frameworks (MOFs), hyper-crosslinking polymer (HCPs), covalent organic frameworks (COFs), activated carbons (ACs), functionalized graphene, chemically modified mesoporous materials, and so forth[5,6]. Microporous materials including activated carbons (ACs) have been regarded as competent candidates for carbon dioxide capture and storage at ambient temperatures, due to their large surface areas, high physical and chemical stability and low density[8]. It is commonly used to produce various porous carbons, such as carbon nanotubes, graphene, and activated carbons In the latter one, many nitrogen-containing precursors are directly used as precursors to produce nitrogen-functionalized carbonaceous materials[21], including poly aniline (PNI), poly pyrrole (PPy)[22], melamine analogues[23] and poly acrylonitrile[14]. We present a facile strategy, which involves a new type of polyimine direct pyrolysis with KOH as a chemical activating agent in the tubular furnace by adjusting the activation temperature, to prepare (i) highly ordered N-doped porous activated carbon using polyimine as an organic precursor (ii) naturally occurring nitrogen is preserved as dopants to motivate molecular adsorption, e.g. for CO2 capture. The resultant N-doped porous carbon exhibits a high CO2 adsorption capacity, and more interestingly a high selectivity for CO2 over N2
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