CO2 Adsorption on Hazelnut-Shell-Derived Nitrogen-Doped Porous Carbons Synthesized by Single-Step Sodium Amide Activation

In this paper, using carbonized hazelnut shells as the raw material and sodium amide as both activator and nitridation agent, N-enriched carbonaceous sorbents were successfully made by an one-step reaction at a relatively low temperature range of 500–600 °C. This strategy can effectively solve the corrosion problems caused by KOH activation, and avoid the tedious, time-consuming, and multistep nitriding-activation processes to prepare nitrogen-doped porous carbons. The resultant carbonaceous adsorbents were properly characterized, and their CO2 adsorption properties were carefully investigated. Excellent CO2 adsorption abilities, i.e., 4.32 and 6.23 mmol/g at 25 and 0 °C under 1 bar, respectively, were accomplished by these hazelnut-shell-based carbons. It is also found that their CO2 uptake under the ambient conditions are determined by the comprehensive effects of narrow microporosity, N content, pore size, and pore size distribution of the adsorbents rather than by any single factor. Besides the high CO2 uptake, these hazelnut-shell-derived carbons also display many other outstanding CO2 capture properties such as moderate heat of adsorption, high selectivity of CO2/N2, fast adsorption kinetics, good recyclability, and dynamic CO2 capture capacity. Excellent CO2 capture properties, using waste as precursor, and a facile preparation strategy make these hazelnut-shell-based carbons attractive in CO2 capture.