N-Doped Porous Activated Carbon Monolith using for CO2/N2 Selectivity
Hierarchical porous carbon (HPC) monolithic with 3D network has received considerable attention due to their potentially technological application as candidates for electrochemical energy storage devices such as capacitors, lithium ion batteries, solar cells, sorbent for toxic gas separation and greenhouse gas capture for their well-defined pore dimensions and topologies. Synthetic polymer based hierarchical nanostructured carbons are particularly attractive for their consistent pore dimensions which can be adjustable on long length scales, so that diffusibility of guest species could be improved through its unique hierarchical pores. N-doped HPC monoliths exhibit multifaceted features such as tunable textural properties, excellent thermal and chemical stability, which are remarkable physicochemical properties that are answerable for micro/nanostructured porous carbons perfect candidates for emerging substrates in nanotechnology science.
A two-step synthetic method has been developed to achieve functionalized nanoporous carbons via cross-linked polymer precursors, which are prepared by Friedel-craft alkylation and pyrolysis as showen in fig. 1. Nitrogen-doping proves to be an effective method for reinforcing the CO2 adsorption capacity of carbon-based adsorbents, although it remains a great challenge to reach a fit doping level of nitrogen (N) and a high porosity in a porous carbon simultaneously. Herein, a facile method that enables the fabrication of ordered microporous nitrogen-doped porous carbon monolith with a content of 4.6 wt% N, which employs poly (H-BINAM) as precursor. Through chemical activation, high microporosity is generated and gives birth to a monolithic structured porous nitrogen-doped carbon. This material exhibits a remarkable CO2 adsorption capacity (6.74 mmol g-1 at 273 K and 4.27 mmol g-1 at 298 K under 1 bar), and an extraordinarily excellent CO2/N2 selectivity (153), which is calculated from the single-component adsorption isotherms based on Henry’s Law. This value exceeds the CO2/N2 selectivity of thus mentioned for carbon-based adsorbents including diverse nitrogen doped ones, whose attributes are largely associated with the unusually high N-content as well as the partial graphitic framework.
Keywords: activated carbon, CO2 capture, nitrogen content, selectivity .