原位水热合成Ce(Ⅳ)-X分子筛及对噻吩的吸附性能

In situ hydrothermal synthesis of cerium-incorporated X zeolites and their performance in thiophene adsorption

  • 摘要: 通过原位水热合成方法直接制备出不同载Ce量的Ce(Ⅳ)-X分子筛,并考察了其对模拟汽油中噻吩的吸附性能。采用粉末X射线衍射(XRD)、傅里叶变换红外(FT-IR)、紫外-可见漫反射(UV-vis DRS)、全谱直读等离子体原子发射光谱(ICP-AES)、氮气吸附和NH3程序升温热脱附(NH3-TPD)等方法对分子筛进行表征。结果表明,合成分子筛均具备典型的X型分子筛结构,同时Ce(Ⅳ)被较好地引入到分子筛的骨架结构中;载Ce分子筛的酸性大于X分子筛,而且Ce(Ⅳ)-X分子筛的酸性随着Ce掺杂量的增加而增强。吸附实验表明,载Ce分子筛对噻吩的吸附性能明显好于X分子筛。其中,n(Ce)/n(Si)=0.05的分子筛脱硫效果最佳,饱和吸附容量达到52.541 9 mg/g。再生实验表明,加热再生的Ce(Ⅳ)-X分子筛对噻吩仍具有理想的吸附效果。n(Ce)/n(Si)=0.05的分子筛再生后饱和吸附容量为47.512 1 mg/g,约为新鲜吸附剂的90.43%。

     

    Abstract: A series of cerium-incorporated X zeolites (Ce(IV)-X) with different Ce/Si molar ratios were prepared by in situ hydrothermal synthesis and used as adsorbents to remove thiophene from a model fuel. The synthesized Ce(IV)-X zeolites were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), diffuse reflectance ultraviolet spectroscopy (UV-vis DRS), plasma atomic emission spectrometry (ICP-AES), N2 adsorption, and NH3 temperature programmed desorption (NH3-TPD). Results reveal that the synthesized Ce(IV)-X zeolites exhibit typical structure of X zeolites and cerium (IV) ions are well dispersed in the framework of X zeolites. The acidity of Ce(IV)-X is enhanced by incorporating cerium, especially at high cerium content. The synthesised Ce(IV)-X zeolites exhibit better capability for the adsorption of thiophene from the model fuel than X zeolites; the Ce(IV)-X sample with n(Ce)/n(Si)=0.05 performs best, possessing a saturated adsorption amount of 52.541 9 mg/g. Moreover, the spent Ce(IV)-X after regeneration still has a perfect adsorption ability towards thiophene; the regenerated Ce(IV)-X sample with n(Ce)/n(Si)=0.05 has a saturated adsorption amount of 47.512 1 mg/g, i.e. 90.43% of that for the fresh adsorbent.

     

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