Characterization of Fluorinated Hβ Zeolite with NH4F
Fluorination of the zeolite has been known as a useful method to modify its acidity and surface performance. In this paper, a set of zeolite Hβ were impregnated with aqueous solution of NH4F. The effects of NH4F impregnation on the structure and acidity of Hβ was investigated by XRD, BET measurements, NH3-TPD, and Py-IR. The change of specific surface area and pore volume of the fluorinated samples with NH4F can be attributed the reaction of NH4F with non-framework and framework aluminum. The fluorination increases the strength and changes the distribution of the acid sites; the fluorination also leads to the decrease of the total acid sites and the Brönsted acid sites due to the dealuminization of the samples and the substitution of the OH- by fluorine atoms.
Guojun Zhang and Jessica Xu
Z. Tian and N. C. Bing, "Characterization of Fluorinated Hβ Zeolite with NH4F", Advanced Materials Research, Vols. 160-162, pp. 524-528, 2011