New Cu_2O-SiO_2 Composite Aerogel-like Desulfurization Adsorbents with Different Molar Ratio of Si/Cu Based on π-Complexation

摘要

Cu2O-SiO2 composite aerogel-like adsorbents with different n(Si/Cu) were synthesized by a sol-gel method, followed by drying under atmospheric pressure, and characterized by BET, XRD, SEM, H-2-TPR, XRF, and FTIR means. Their adsorption performance for thiophene and benzothiophene in model fuels was investigated with equilibrium and breakthrough adsorption experiments, respectively. The results showed that Cu2O-SiO2 composite aerogel-like adsorbents exhibited an excellent desulfurization performance based on pi-complexation between Cu(I) and thiophenics. The n(Si/Cu) of Cu2O-SiO2 had an obvious effect on their physical properties and consequently desulfurization performance. The BET surface area, pore size, and pore volume decreased with the decrease of n(Si/Cu) (increase of Cu content). Only a part of Cu was incorporated into the materials. The more the Cu(I) and the higher the specific surface area, the larger the adsorption capacity was. Cu2O-SiO2-50 performed the best, and breakthrough adsorption capacities for benzothiophene and thiophene were 5.78 mg S/g(ads) (0.90 mmol-S/mmol-Cu) and 4.76 mg S/g(ads) (0.74 mmol-S/mmol-Cu), respectively. The adsorption data can be well fitted by both the Langmuir and Freundlich adsorption isotherms. The effect of competitive adsorption of olefins or aromatics on the desulfurization performance of adsorbents was obviously weaker compared with the result in the literature. The spent Cu2O-SiO2 adsorbents can be well regenerated by benzene-n-heptane washing. The breakthrough adsorption capacity of thiophene on the first regenerated Cu2O-SiO2-50 was 71% of that on fresh adsorbent.