Analysis of theoretical and experimental X-ray diffraction patterns for distinct mordenite frameworks

Abstract

Experimental and theoretical XRD patterns of mordenite frameworks were correlated in this work. The experimental XRD analysis showed that the incorporation of Ag and Fe ions in mordenite modified the intensity of peaks in the diffraction patterns. For theoretical studies, two framework models of mordenite (MOR6 and MOR7) were used. Theoretical results conducted through DFT computational simulations were able to predict correctly the angular positions of the experimental peaks observed in XRD patterns. These theoretical results showed that the ion exchange of $${\hbox {Na}^{+}}$$ by $${\hbox {Ag}^{+}}$$ cations in the zeolitic framework leads to a decrease in intensity of XRD peaks {2 0 0}, {0 2 0} and {1 5 0}, similar to observed experimentally. This is caused by local structural rearrangements produced by the ion exchange. For $${\hbox {Fe}}$$ incorporation in zeolite, two options were considered theoretically: ion exchange and isomorphous substitution of $${\hbox {Al}^{3+}}$$ in tetrahedral positions.