Influence of doping nitrogen, sulfur, and phosphorus on activated carbons for gas adsorption of H2, CH4 and CO2

Abstract

Hexagonally packed mesoporous silica (HMS) was used as a kind of template-like material to prepare heteroatom doped porous carbons from the polymerization reactions of resorcinol and formaldehyde in the HMS pore channels. Different acids (HNO₃, H₂SO₄, H₃PO₄) were used to catalyze the polymerization reactions to obtain N-doped, S-doped, and P-doped porous carbons, respectively. The adsorption properties of H₂, CH₄, and CO₂ were investigated on these doped carbon materials systematically. For the hydrogen adsorption, the adsorption amount was 11.8%, 21.1%, and 33.3% higher on N-doped, S-doped, and P-doped porous carbons, respectively, than the carbon sample without doping, and the highest hydrogen uptake reached 14.88 mmol g⁻¹ on the P-doped sample; regarding the CO₂ adsorption, the adsorption amount reached 3.60 mmol g⁻¹ and 3.16 mmol g⁻¹ on the S-doped sample and N-doped sample, respectively, which is 39.5% and 22.5% higher than the sample without doping; it also shows that methane uptake amount was significantly increased by 27.1% on the S-doped sample as compared to the sample without doping, i.e., 3.52 mmol g⁻¹ of CH₄. Therefore, it is predicted that these doped carbon materials with high specific surface area are of great potential for the gas adsorption of H₂, CH₄, and CO₂.