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 m(2)/g and 0.71 cm(3)/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 m(2)/g and 0.64 cm(3)/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. (C) 2016 Elsevier B.V. All rights reserved.