High-efficiency adsorption of aromatic sulfur-containing species by ZnCl2-chitosan polymer derived Zn, N-cooperated highly porous carbon

Abstract

The removal of aromatic sulfur-containing species by adsorption method in liquid hydrocarbon fuels (LHFs) are concerned in worldwide, but it is still a challenge due to intricacy-designed adsorbents, resulting in high cost of preparation and poor stability. Herein, an easy-prepared adsorbent, Zn-NC-T (T represents the carbonization temperature, T = 600, 800 and 1000 °C), which derived from the carbonization of low-cost ZnCl2-chitosan polymers, is reported. The optimal Zn-NC-800 exhibits dibenzothiophene (DBT) uptakes of 43.3 mg S/g, which is superior to many reported desulfurization adsorbents, including metal–organic frameworks, zeolites and metal-loaded porous carbons. It also keeps satisfactory reusability with adsorption capacity loss of 5.3 mg S/g after 5 cycles because of the high-efficiency removal of adsorbates under high temperature regeneration. Moreover, the Zn-NC-800 shows great potential for sulfur-free LHFs production in the industry by breakthrough experiment for adsorbing low-concentration DBT (100 ppmw S) with ca. 0 ppmw S content in outlet LHFs. And the mechanism investigation on the adsorption isotherms and kinetics indicates that the adsorption process of DBT is controlled by chemisorption. Furthermore, DFT calculations suggest that the Zn, N-co-doped carbons show stronger adsorption strength (e.g., DBT, −1.79 eV) than the sole N-doped carbons (−0.93 eV), indicating the main contribution of Zn, N-cooperated adsorptive sites. The reported Zn-NC-T equips with advantages of low-cost raw materials, high adsorption capacity and good reusability, making it promising candidate for production of sulfur-free LHFs.