Oxygen-enriched surface modification for improving the dispersion of iron oxide on a porous carbon surface and its application as carbon molecular sieves (CMS) for CO₂/CH₄ separation

The separation of CO2/CH4 can be enhanced by impregnating porous carbon with iron oxide. Dispersion of iron oxide is one of the critical factors which supports the separation process performance. Iron oxide dispersion can be enhanced by enriching the oxygen functional groups on the carbon surface. This study investigates three distinct oxidation processes: oxidation with a 10% H2O2 solution, ozonation with distilled water, and ozonation with a 10% H2O2 solution. The research steps included the following: (i) oxidation, (ii) impregnation of iron oxide followed by calcination, (iii) material characterization, and (iv) material performance analysis. Materials were characterized using N-2 sorption analysis, X-ray diffraction analysis (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy analysis (SEM-EDX), and Fourier transform infrared analysis (FT-IR). Iron oxide was well dispersed on the carbon surface, as evidenced by the elemental mapping of materials. In addition, the oxygen functional groups increased significantly in the range of 28.6-79.7% following the oxidation process, as indicated by the elemental component using SEM-EDX analysis. The impregnation of iron oxide on oxidized carbon ozonated with distilled water (COA-Fe) obtained a maximum CO2 uptake capacity of 3.0 mmol g(-1) and CO2/CH4 selectivity increased by up to 190% at a temperature of 30 degrees C and pressure of 1 atm. Furthermore, the enhancement of CO2/CH4 separation up to 1.45 times was the best performance achieved by COA-Fe. Thus, improving iron oxide dispersion on oxidized carbon surfaces has a potential application in CO2/CH4 separation.