Effects of bimetallic Ce/Fe nanoparticles on the desulfurization of thiophenes using activated carbon

Activated carbon (AC) was loaded with two different metals: cerium and iron. Three composites were prepared namely AC/Ce, AC/Fe, and AC/Ce/Fe. The composites were investigated for the simultaneous desulfurization of thiophene, benzothiophene (BT), and dibenzothiophene (DBT) in a model fuel. The surface structures, morphologies, and pore structures were characterized. The unloaded AC had the highest surface area and pore volume of 460.27 m²/g and 0.71 cm³/g respectively. Moreover, the unloaded AC showed the highest surface oxygen-containing groups but performed the least in desulfurization. The adsorptive desulfurization efficiency followed the order: AC < AC/Fe < AC/Ce < AC/Ce/Fe. The AC/Ce/Fe performed the best in the adsorption of thiophene (31%), BT (30%), and DBT (75%) despite having the least surface area and pore volume of 430.44 m²/g and 0.64 cm³/g. All the adsorbents showed a greater affinity to the large size DBT. Batch and column experiments carried out using AC/Ce/Fe revealed a high absorptive capacity and breakthrough for DBT i.e. 16 mg/g. The kinetic data showed a synergistic effect of surface adsorption and intraparticle diffusion occurring concurrently, and the results complied with the pseudo-second-order kinetic model. The equilibrium adsorption results are well fitted to the Freundlich isotherm indicating a heterogeneous adsorption process. Thermal regeneration experiments carried out on AC/Ce/Fe showed stable efficiency in the adsorptive desulfurization after regeneration cycles. The regeneration properties displayed by the adsorbent could enhance its practical application in an industrial setting.