Highly Efficient Nitrogen-Doped Porous Carbonaceous CO2 Adsorbents Derived from Biomass

In this manuscript, N-doped porous carbonaceous CO2 sorbents were synthesized using biomass waste hazelnut shell as the raw materials, melamine as the nitridation agent, and KOH as the porogen. The resultant materials were carefully characterized by different techniques, and the results show that these samples possess a high amount of N content and highly developed porous structure. As a result, high CO2 adsorption capacities were found for this series of sorbents, up to 4.23 and 6.34 mmol/g at 1 bar and 25 and 0 °C, respectively. Comprehensive investigation indicates that, in addition to the well-known narrow microporosity and N content, the pore size distribution of the adsorbent also plays an important role in dictating the CO2 uptake under ambient conditions. Thus, it is proposed that the joint effect of the above three factors dictates the CO2 adsorption capacity of these sorbents. Moreover, these sorbents exhibit many other exceptional CO2 adsorption properties, such as stable recyclability, fast adsorption kinetics, suitable heat of adsorption, high CO2/N2 selectivity, and good dynamic CO2 capture capacity. The wide availability and low cost of raw materials together with a straightforward synthesis procedure and excellent performance disclose the high potential of hazelnut-shell-derived carbons in CO2 capture.