Mesoporous carbon adsorbents from melamine-formaldehyde resin using nanocasting technique for CO2 adsorption

• Published in: Journal of environmental sciences (China) 2015-06, Vol.32 (6), p.238-248
• Main Authors: Goel, Chitrakshi, Bhunia, Haripada, Bajpai, Pramod K.
• Format: Article
• Language: English
• Subjects: Adsorption; Air Pollutants - isolation & purification; Carbon; Carbon - chemistry; Carbon Dioxide - isolation & purification; CO2; CO2 adsorption; Isotherm; Mesoporous; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nanocasting; Resins, Synthetic - chemistry; Silicon Dioxide - chemistry; Spectroscopy, Fourier Transform Infrared; Surface Properties; Thermogravimetry; Triazines - chemistry; X-Ray Diffraction; 三聚氰胺甲醛树脂; 介孔二氧化硅; 吸附性能; 扫描电子显微镜; 碳材料; 纳米技术; 透射电子显微镜
• ISSN: 1001-0742; 1878-7320
• DOI: 10.1016/j.jes.2014.12.021

Mesoporous carbon adsorbents, having high nitrogen content, were synthesized via nanocasting technique with melamine-formaldehyde resin as precursor and mesoporous silica as template. A series of adsorbents were prepared by varying the carbonization temperature from 400 to 700°C. Adsorbents were characterized thoroughly by nitrogen sorption, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, thermogravimetric analysis（TGA）, elemental（CHN） analysis, Fourier transform infrared（FTIR） spectroscopy and Boehm titration. Carbonization temperature controlled the properties of the synthesized adsorbents ranging from surface area to their nitrogen content, which play major role in their application as adsorbents for CO2 capture.The nanostructure of these materials was confirmed by XRD and TEM. Their nitrogen content decreased with an increase in carbonization temperature while other properties like surface area, pore volume, thermal stability and surface basicity increased with the carbonization temperature. These materials were evaluated for CO2 adsorption by fixed-bed column adsorption experiments. Adsorbent synthesized at 700°C was found to have the highest surface area and surface basicity along with maximum CO2 adsorption capacity among the synthesized adsorbents. Breakthrough time and CO2 equilibrium adsorption capacity were investigated from the breakthrough curves and were found to decrease with increase in adsorption temperature. Adsorption process for carbon adsorbent-CO2 system was found to be reversible with stable adsorption capacity over four consecutive adsorption-desorption cycles. From three isotherm models used to analyze the equilibrium data, Temkin isotherm model presented a nearly perfect fit implying the heterogeneous adsorbent surface.