Simultaneous desulfurization and denitrogenation of model fuels by polyethylene glycol-modified resorcinol/formaldehyde resin-derived carbon spheres

Abstract

A series of resorcinol/formaldehyde (RF) resin-derived carbon spheres modified by polyethylene glycol (PEG) were prepared. The effects of PEG addition time during hydrothermal treatment and molecular weight on the pore structure, surface acidic groups, particle size, and adsorption performances of the obtained spherical activated carbons were investigated. Two types of model fuel containing indole, quinoline, and dibenzothiophene (DBT) as target adsorbates were prepared to evaluate the adsorption performances of the spheres, which increased in the order of DBT<quinoline<indole. Hydrogen bonding may be critical in the removal of indole. Both the surface area and oxygen-containing functional groups influenced the adsorption capacity, with the latter significantly influenced by PEG addition time. PEG addition during the RF resin cross-linking stage sharply reduced the total concentration of acidic groups on the carbon sphere surfaces. The adsorption thermodynamics and kinetics of nitrogen and sulfur compounds were also investigated. The adsorption isotherms of all S/N species were of the Freundlich type at 25 oC. The pseudo-second-order rate equation well described the adsorption kinetics. Both external diffusion and intra-particle diffusion controlled the rate of adsorption.