Highly Selective Deep Desulfurization of a Model Gasoline on Amine-Modified SiO2 Hybrid Aerogel

Amine-modified SiO2 hybrid aerogel desulfurization adsorbents with varied Si/N molar ratios (SiO2-NH2-n) were prepared via the sol–gel method followed by the atmospheric drying technique. SiO2-NH2-n aerogels were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), in situ Fourier transform infrared (FT-IR), and N2 adsorption–desorption. The desulfurization performances of SiO2-NH2-n were studied by the batch and breakthrough adsorption experiments. SiO2-NH2-n exhibited an obvious improvement in adsorption capacity for thiophenics compared with SiO2 aerogel due to the hydrogen bonding between thiophenics and amino groups. Among them, SiO2-NH2-8 had the best performance, and the adsorption capacities for thiophene, benzothiophene, and dibenzothiophene were 6.8, 9.5, and 10.2 mg S/gads, respectively. No effect of toluene and cyclohexene on the adsorption of SiO2-NH2-8 for thiophene was observed. The equilibrium adsorption data of SiO2-NH2-8 for thiophene were well fitted by the Freundlich model, indicating that multilayer adsorption occurred on the heterogenetic surface of SiO2-NH2-8. The kinetic adsorption data of SiO2-NH2-8 for thiophene could correlate properly with the pseudo-second-order kinetic model, suggesting that the rate-controlling steps involve surface adsorption. The saturated SiO2-NH2-8 could be regenerated completely via heating at 393 K for 12 h, and the regenerated SiO2-NH2-8 afforded 100% breakthrough adsorption capacity for thiophene.