Hydrogen adsorption on the zeolite Ca-A: DFT and FT-IR investigation

[EN] Adsorption of H(2) on the zeolite Ca-A was investigated by a combination of variable temperature IR spectroscopy and calculations at the periodic DFT level. Calculations showed that adsorption complexes can be formed on two types of adsorption sites: Ca(2+) in the center of six-member rings and Ca(2+) in eight-member rings. Only the former adsorption complexes were experimentally observed in IR spectra; they are characterized by H-H stretching frequency of 4083 cm (1) and Delta H(0) = -12 kJ/mol in agreement with calculated results. The most likely explanation for not observing the adsorption complex on Ca(2+) in 8-member rings is that the geometry of the complex does not render the H-H stretching mode IR active. (C) 2009 Published by Elsevier B. V.Work in Prague was supported by research projects 203/09/0143 (GA C. R), MSM0021620857 and LC512 (MSMT C. R). AP acknowledges the support from Spanish MICINN (post-doctoral fellowship). The Spanish MICINN and FEDER funds are gratefully acknowledged for financial support to the work done at the UIB (Projects MAT2008-00089 and PCI2006-A7-0618). The access to the META Centrum computing facilities provided under the research intent MSM6383917201 is acknowledged.Otero Arean, C.; Turnes Palomino, G.; Llop Carayol, MR.; Pulido Junquera, MA.; Rubes, M.; Bludsky, O.; Nachtigall, P. (2009). Hydrogen adsorption on the zeolite Ca-A: DFT and FT-IR investigation. Chemical Physics Letters. 447(1-3):139-143. doi:10.1016/j.cplett.2009.06.058S1391434471-