Preparation Of N-doped Carbon And Investigation On Its CO₂ Adsorption Property

Among various technologies for carbon capture and storage, adsorption is considered to be one of the most promising techniques in practical application, and the key of the adsorption technology is to develop an effective solid adsorbent. Carbonaceous adsorbents possess unique superiority in CO₂ adsorption. But the pure carbon material suffers from several drawbacks such as low adsorption capacity and selectivity.N-doped carbon materials with high N content and suitable pore structure share potential applications in CO₂ adsorption, due to the combination of physisorption and chemisorption. In this paper, based on the idea of solution chemistry, N-doped porous carbon was prepared by using urea as nitrogen source through a carbonization-activation process. Physical and chemical properties of the obtained materials were characterized by N2 adsorption/desorption, elemental analysis, XRD, SEM, TEM, XPS, FT-IR.N-doped carbon was synthesized using urea resin, and the adsorption property of N-doped carbon and porous carbon nitride was studied. The effects of activation temperature and dosage of KOH were also investigated. The results showed that the obtained N-doped carbon possessed high N content and highly developed pore structure. N content reduced and the pore was enlarged with the activation condition getting severer. The material activated at 600 oC with KOH at a weight ratio of 2 showed high CO₂ adsorption uptake up to 3.2mmol?g-1, at 25 oC,100 kPa.The effects of different carbon sources were also studied. The sample added with furfuralcohol showed higher CO₂ adsorption uptake up to 3.8mmol?g-1 due to large micropore volume less than 1nm though the sample possessed lower nitrogen content and weak basicity. At last, N-doped carbon was prepared by using urea and furfuraldehyde as precursors through a carbonization-activation process. The preparation conditions such as the ratio of precursors and carbonization temperature were investigated. It demonstrated that the sample carbonized at 500 oC with urea/furfuraldehyde at a ration of 1, and activated at 700 oC showed high CO₂ adsorption uptake about 4.6mmol?g-1. The sample had outstanding cycling performance and CO₂/N2 selectivity even after 10 cycles.The study of the relationship between CO₂ adsorption capacity and physicochemical property found that the CO₂ adsorption capacity was mainly depended on the ultra micropore volume less than 0.6nm. The nitrogen-containing groups just enhanced the interaction between the surface of the adsorbents and CO₂ molecules, and the material possessed higher isosteric heat of adsorption.