ZiF-8-derived P, N-co-doped hierarchical carbon: synergistic and high-efficiency desulfurization adsorbents

Abstract

Adsorptive desulfurization is an effective technology for removing aromatic sulfur-containing compounds from liquid hydrocarbon fuels, but the existing adsorbents have poor adsorption performance and stability. Herein, P, N-co-doped metal-free 3D porous carbon was first prepared by ZiF-8 and applied in adsorptive desulfurization. The incorporation of P and N heteroatoms changes the surface chemistry of the carbon skeleton, meanwhile, the P doping effectively adjusts the pore structure of the adsorbents. Accordingly, the P-NPC-1000 exhibited a remarkable adsorption capacity of 60.16 mg S/g for dibenzothiophene (DBT), with a 32% increase in adsorption capacity compared to solely N-doped carbon (45.41 mg S/g). It also demonstrated excellent reusability with adsorption capacity from 54.22 to 48.14 mg S/g after 6 cycles. The Langmuir and the pseudo-second-order kinetic models presented best fitting results for DBT adsorbing on the P-NPC-1000. Moreover, the adsorption mechanism was further investigated through DFT calculations and special adsorption experiments. It was proved that the P- and N- sites cooperate synergistically to enhance the interaction between P, N-co-doped carbon and DBT. The acid-base interaction and polar interaction between P-/N-sites and DBT, together with the pore structure, make the P-NPC-1000 highly promising in adsorptive desulfurization.