Water adsorption fluorinated zeolites

Dilute fluorine gas (0-20%) can be used to treat zeolites at near-ambient temperature and pressure. Most of the resulting materials retain very high crystallinity even after 600°C postcalcination for two hours. Both framework infrared spectra and X-ray powder diffraction patterns clearly show structural dealumination and stabilization. The hydrophobic nature of the fluorine-treated and 600sC-calcined material is shown by a low water adsorption capacity and selective adsorption of n-butanol from a 1 vol.% n-butanol-water solution. Fluorination also changes the catalytic activity of the zeolite as measured by an n-butane cracking method. 

The results indicate that both NH4,TMA-fl and NH.,K-L are de-aluminated upon fluorination. Strong supporting evidence comes from framework I. R. data where the shifts in band position to higher wave numbers are as much as 20 cm-1. However, there is no evidence of structure stabilization. Also McBain water adsorption data give no indication of surface hydrophobicity. Therefore, it is likely that structure defects are formed in these two zeolites as a result of dealumination and cause low thermal stability. 

A simple shake test with aqueous 1 vol % n-butanol solution has been developed to test the selective adsorption of organic molecules over water molecules by a hydrophobic and organophilic adsorbent (26). Table V gives the results for severed, fluorine-treated zeolites and their untreated counterparts. The data clearly indicate that fluorine treatment of LZ-105, H-zeolon and NH4Y materials substantially increases their selectivity for n-butanol over water. 

Fluorinated materials such as zeolites, metal phosphates, and MOFs have been exploited for several applications such as water repellent and corrosion protecting surfaces. Moreover, the same materials have been used for the oil spill cleanup via selective adsorption... 

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