B2O3对Ag/TiO2-Al2O3吸附剂的柴油吸附脱硫性能影响

采用浸渍法制备了不同B₂O₃负载量(e.g. 5%~20% (w))的Ag/TiO₂-B₂O₃-Al₂O₃吸附剂。以含硫量为245.36mg(S)/L 的商业柴油作为考察对象,常温常压下采用静态评价进行吸附脱硫性能研究。结果表明,B₂O₃改性后的Ag/TiO₂-Al₂O₃吸附剂的柴油吸附脱硫活性有了较大提高,当B₂O₃的负载量为15%时,吸附剂的吸附脱硫活性最高,2%Ag/4%TiO₂-15%B₂O₃-Al₂O₃ (w)的饱和吸附硫容达到2.36mg(S)/g 吸附剂。这对于未经预处理的商业柴油而言,吸附脱硫活性已经达到较高水平。采用N₂物理吸附、O₂化学吸附、X射线衍射(XRD)、NH₃程序升温脱附(NH₃-TPD)、傅里叶红外光谱(FT-IR spectra)、¹¹B核磁共振(¹¹B-NMR)等表征手段对不同负载量B₂O₃改性Ag/TiO₂-Al₂O₃吸附剂的织构性质、晶相结构和表面酸性的影响进行研究。关联活性测试和表征结果发现,吸附剂的吸附脱硫活性主要与吸附剂的表面弱酸性有关,而B₂O₃改性在吸附剂表面引入了较多的四配位的BO₄物种,能显著增加吸附剂表面弱酸性位点数量,提高吸附剂的吸附脱硫活性。

Effect of B2 O3 modified Ag/TiO2-Al2 O3 adsorbents on the adsorption desulfurization of diesel

Ag/TiO₂-B₂O₃-Al₂O₃ adsorbents with different B₂O₃ loadings (e.g. 5%~20% (w)) were prepared by impregnation. Static adsorption tests were carried out by contacting the adsorbents with commercial diesel containing 245.36mg(S)/L sulfur at ambient conditions to investigate the adsorption desulfurization activity. The results show that Ag/TiO₂-Al₂O₃ modified by B₂O₃ exhibits a great enhancement for the adsorption desulfurization activity. When B₂O₃ (15%) was loaded, 2%Ag/4%TiO₂-15%B₂O₃-Al₂O₃ (w) could achieve the best desulfurization activity with a saturation capacity of 2.36mg(S)/g adsorbent. This is a significant achievement regarding the desulfurization efficiency, especially for commercial diesel without pretreatment. The effects of B₂O₃ on the textural properties, crystal structure and surface acidity properties of the adsorbent were studied by N₂-physisorption, O₂-chemisorption, X-ray diffraction (XRD), temperature-programmed desorption of ammonia (NH₃-TPD), Fourier transform infrared spectrometer (FT-IR spectra) and ¹¹B nuclear magnetic resonance (¹¹B-NMR) techniques. Correlating the characterizations with the desulfurization activity, it is found that the adsorption desulfurization activity is well related with the amounts of weak acid sites on the adsorbents. B₂O₃ modification induces larger amounts of BO₄ species and improves the surface weak acidity, resulting in a higher adsorption desulfurization activity.