Efficient nitrogen doped porous carbonaceous CO2 adsorbents based on lotus leaf.

In this work, the waste biomass lotus leaf was converted into N-doped porous carbonaceous CO2 adsorbents. The synthesis process includes carbonization of lotus leaf, melamine post-treatment and KOH activation. For the resultant sorbents, high nitrogen content can be contained due to the melamine modification and advanced porous structure were formed by KOH etching. These samples were carefully characterized by different techniques and their CO2 adsorption properties were investigated in detail. These sorbents hold good CO2 adsorption abilities, up to 3.87 and 5.89 mmol/g at 25 and 0°C under 1 bar, respectively. By thorough investigation, the combined interplay of N content and narrow microporous volume was found to be responsible for the CO2 uptake for this series of sorbents. Together with the high CO2 adsorption abilities, these carbons also display excellent reversibility, high CO2/N2 selectivity, applicable heat of adsorption, fast CO2 adsorption kinetics and good dynamic CO2 adsorption capacity. This study reveals a universal method of obtaining N-doped porous carbonaceous sorbents from leaves. The low cost of raw materials accompanied by easy synthesis procedure disclose the enormous potential of leaves-based carbons in CO2 capture as well as many other applications.

Superior CO2 uptake on nitrogen doped carbonaceous adsorbents from commercial phenolic resin.

In this study, N-doped porous carbons were produced with commercial phenolic resin as the raw material, urea as the nitrogen source and KOH as the activation agent. Different from conventional carbonization-nitriding-activation three-step method, a facile two-step process was explored to produce N-incorporated porous carbons. The as-obtained adsorbents hold superior CO2 uptake, i.e. 5.01 and 7.47 mmol/g at 25 °C and 0 °C under 1 bar, respectively. The synergistic effects of N species on the surface and narrow micropores of the adsorbents decide their CO2 uptake under 25 °C and atmospheric pressure. These phenolic resin-derived adsorbents also possess many extremely promising CO2 adsorption features like good recyclability, quick adsorption kinetics, modest heat of adsorption, great selectivity of CO2 over N2 and outstanding dynamic adsorption capacity. Cheap precursor, easy preparation strategy and excellent CO2 adsorption properties make these phenolic resin-derived N-doped carbonaceous adsorbents highly promising in CO2 capture.