苯并噻吩在酸改性NaY分子筛上的吸附

Adsorption of benzothiophene over acid modified NaY zeolites

以NaY分子筛为母体,通过柠檬酸、磷酸改性分别得到吸附剂NaY-C和NaY-P。采用SEM、XRD、XRF、N2物理吸附及NH3-TPD表征可知,柠檬酸改性后得到的NaY-C吸附剂介孔表面积增加,分子筛骨架结构保持不变。同时,磷酸改性使得NaY分子筛表面弱酸量减少强酸量增加,改性后所得吸附剂NaY-P的强酸量大于NaY-C。吸附实验表明,NaY-C和NaY-P均可完全脱除模拟油品中的苯并噻吩,同时NaY-C吸附剂对0#柴油的脱硫能力优于NaY-P吸附剂。再生实验中NaY-C和NaY-P吸附剂对模拟油品的脱硫率由第一次的100%分别下降至第6次的91.97%和85.96%。由此可知,柠檬酸改性NaY分子筛所得NaY-C吸附剂的脱硫能力优于NaY-P,原因是吸附剂上的介孔更易于发生吸附脱硫。

NaY-C and NaY-P adsorbents were successfully obtained through modifying parent NaY zeolite with citric acid and phosphate acid,respectively. The obtained adsorbents were characterized by scanning electron microscope,X-ray diffraction,X-ray fluorescence,N2 sorption and temperature programmed desorption of NH3.The mesopore surface area of the NaY-C adsorbent was increased when the parent NaY zeolite was modified by citric acid,w ith preserving he zeolite skeletal structure. Meanw hile,the decreased weak acid and increased strong acid content were observed in NaY zeolite modified with phosphate acid aqueous solution and the amount of strong acid sites in the NaY-P adsorbent was more than in the NaY-C adsorbent. The adsorption desulfurization results showed that the NaY-C adsorbent exhibited much higher desulfurization activity than the NaY-P adsorbent in the No. 0 diesel oil,although all benzothiophene in model diesel was removed over both. In regeneration experiment,the benzothiophene removal of model diesel oil decreased from 100% to 91. 97% and85. 96% after six regenerations over NaY-C and NaY-P adsorbents, respectively. Therefore, the NaY-C adsorbent possessed better desulfurization performance, possibly because the mesopore of the adsorbent is beneficial to the adsorption desulfurization.