Synthesis of nitrogen doped mesoporous carbons for carbon dioxide capture

Abstract

Nitrogen doped mesoporous carbons were prepared by nanocasting method at varying carbonization temperatures followed by characterization in terms of their structural, textural and chemical properties. Melamine-formaldehyde resin and mesoporous silica were used as the polymeric precursor and hard template respectively. Meso-structural ordering of the template was retained by the prepared carbons as suggested by the structural analysis. Evolution of nitrogen and oxygen functionalities along with textural properties of nitrogen doped carbons were regulated by the carbonization temperature. The prepared carbons obtained by carbonization at 700 °C exhibited a maximum surface area of 266 m² g⁻¹ along with a nitrogen content up to 21 weight%. CO₂ adsorption was studied in a fixed-bed column at several temperatures (30 to 100 °C) and CO₂ concentrations (5 to 12.5%). Adsorbent reusability was examined by carrying out multiple adsorption–desorption cycles. MF-700 showed the highest CO₂ adsorption capacity of 0.83 mmol g⁻¹ at 30 °C. CO₂ adsorption kinetics were investigated by fitting experimental CO₂ uptake data to different adsorption kinetic models, out of which the fractional order model was found to fit over the complete adsorption range with the error% between experimental and model predicted data within the range of 5%. In addition, the isosteric heat of adsorption was estimated to be around 17 kJ mol⁻¹, confirming the occurrence of the physiosorption process.