CHARACTERIZATION OF MORDENITES TREATED BY HCL STEAM OR HF/

Mordenites were modified by dealumination with HCl/steam or HF treatme nt, and characterized by X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), infrared spectroscopy, s canning electron microscopy (SEM) and nitrogen adsorption. All mordeni tes retained more than 80% crystallinity, although the lattice paramet ers (a, b, c) were reduced more for HCl/steam-treated mordenites than for HF-treated mordenites. In the HCl/steam-treated mordenites, framew ork aluminum was mainly removed, while in the I-IF-treated mordenites, framework aluminum was removed extensively at the beginning of treatm ent, and thereafter silicon and aluminum were simultaneously removed. Mesopores with a diameter of 3.7 nm developed as a result of dealumina tion, which did not depend on the treatment methods. The acid strength was higher on the HCl/steam-treated mordenites than on the HF-treated mordenites. (C) 1998 Elsevier Science B.V. All rights reserved.