A facile fabrication of highly dispersed CeO2/SiO2 aerogel composites with high adsorption desulfurization performance

A simple, low energy consumption and environment-friendly strategy was used to prepare highly dispersed CeO2/SiO2 aerogel composites with different molar ratio of Si/Ce via sol-gel method and subsequently drying under the ambient pressure, in which the oxidation of Ce3+ species into Ce4+ species could be achieved by adding H2O2. The structural and surface properties of adsorbents were analyzed by XPS, XRD, FT-IR, Py-IR, SEM, XRF and N2 adsorption-desorption isotherm. The adsorption desulfurization performances of CeO2/SiO2 for thiophenic compounds from simulated gasoline and model aromatic products were investigated and compared by the breakthrough and batch adsorption experiments. As a result, the weak Lewis acid centers appeared on the surface of CeO2/SiO2. Among them, CeO2/SiO2 with a Si/Ce of 25 performed best, the adsd by Duanpacity for TP from simulated gasoline (n-heptane) was 10.9 mg-S/gads, followed by model aromatic products (benzene, 10.6 mg-S/ gads; p-xylene, 10.1 mg-S/gads), however, the difference between them was slight, attributed to the formation of S-Ce bonding instead of C-Ce bonding. The very weak competitive adsorption of benzene and p-xylene with thiophene originated from the weak Lewis acid-base interaction. After the fourth solvent washing regeneration, the breakthrough adsorption capacity of regenerated CeO2/SiO2-25 still remained 60% of the fresh one. The equilibrium adsorption data of CeO2/SiO2-25 for thiophene were well fitted by Langmuir and Freundlich model, and the adsorption for TP was more favorable at the higher temperature. The adsorption process of CeO2/SiO2-25 was well fitted by pseudo-second-order kinetic model, which was spontaneous, endothermic and the freedom degree increased. The solvent (n-heptane, benzene, p-xylene) hardly influence the adsorption behavior of TP on CeO2/SiO2.