Application of IR spectra in the studies of zeolites from D4R and D6R structural groups

作者：Krol M^*; Mozgawa W; Jastrzebski W; Barczyk K

来源：Microporous and Mesoporous Materials, 2012, 156: 181-188.

DOI：10.1016/j.micromeso.2012.02.040

• Infrared spectra
• Zeolite
• Structural units
• Sorption
• Heavy metals

This work presents results of FT-IR spectroscopic studies (MIR and FIR range) of zeoles (belonging to D4R and D6R structural groups) after heavy metal cations (Ag+, Cu2+, Cd2+, Pb2+, Zn2+, Ni2+ and CP3+) immobilization. Sorption has been conducted on monoionic forms of synthetic zeolite A (LTA) and Y (FAU) as well as on natural chabazite (CHA). %26lt;br%26gt;It was proven that those cations%26apos; sorption causes changes in the spectra of the zeolites. Changes in intensities and positions of the bands corresponding to the characteristic ring and Me-O vibrations have been observed. These rings occur in pseudomolecular complexes (built of alumino- and silicooxygen tetrahedra) which constitute the secondary building units (SBU) and form spatial framework of the zeolite. Based on the results of DFT method (B98 HF 6-31G(d)) calculations, normal vibrations of the SBU terminated by different cations (Na+, K+) have been visualized. Obtained results have been applied for interpretation of experimental spectra of selected zeolites. The most significant changes have been determined in the region of pseudolattice vibrations (800-550 cm(-1)). On the other hand, an introduction of heavy metal cations into the structure of zeolites has caused the considerable modification of bands due to Me-O vibrations in FIR spectra (below 400 cm-1). %26lt;br%26gt;In both cases systematic changes connected with the type of cation (its chemical character) have been revealed. Based on changes in the spectra due to immobilization of heavy metal ions, a scale of sorption can be established.

• 出版日期2012-7-1