The effect of metal ions in MNaY-zeolites for the adsorptive removal of tetrahydrothiophene

The adsorptive removal of tetrahydrothiophene (THT) was carried out over transition metal ion-exchanged Na-Y zeolites. CuNa-Y, CoNa-Y, NiNa-Y and FeNa-Y were prepared by a conventional ion exchange method from Na-Y using the nitrate solutions of corresponding metals. N₂ physisorption, inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and X-ray diffraction were conducted to characterize adsorbents. The temperature programmed desorption (TPD) of THT was also perfomed to probe the interaction between the adsorbent and the THT. The crystal structure of Y-zeolite was completely destroyed in FeNa-Y, which resulted in a insignificant amount of adsorbed THT. The breakthrough capacity, which is defined as the amount of sulfur adsorbed on the adsorbent before detecting sulfur species by PFPD, decreased in the following order CuNa-Y>CoNa-Y>NiNa-Y≫FeNa-Y. For interaction between THT and adsorbent, a TPD peak appeared over CoNa-Y at the highest temperature, which implies that the strongest interaction can be made between THT and Co²⁺ in CoNa-Y.