Characterization of basicity in alkali cation exchanged Faujasite zeolites: an XPS study using chloroform as a probe molecule

The basicity of alkali exchanged zeolites was characterized by chloroform adsorption using XPS spectroscopy. Chloroform is mainly adsorbed on the basic sites (framework oxygen) through its hydrogen atom. The results of C12p deconvolution show that in zeolites chloroform is adsorbed only on the more strongly basic sites associated with the framework oxygens directly adjacent to alkali cations. The charge on the chlorine atoms was calculated using the principle of equalization of electronegativities. The C12p binding energy shift is well correlated with this partial charge on chlorine atoms.The slope of the straight line of Cl2p binding energy change with the negative charge on chlorine is high, which indicates that chloroform is a good probe molecule for monitoring the basicity on zeolites by XPS.