Adsorption of dihydrogen onto the zeolites Na-ZSM-5 and K-ZSM-5 renders the fundamental H-H stretching mode infrared active. The corresponding infrared absorption bands were found at 4101 and 4112 cm-1 for H 2/Na-ZSM-5 and H2/K-ZSM-5, respectively. Thermodynamic characterization of the adsorbed state was carried out by means of variable-temperature infrared spectroscopy; simultaneously measuring integrated band intensity, temperature and equilibrium pressure of the gas phase. For the H2/Na-ZSM-5 system, the standard adsorption enthalpy and entropy resulted to be ΔH° = -10.3 (±0.5) kJ mol-1 and ΔS° = -121 (±10) J mol-1 K-1. For H 2/K-ZSM-5 corresponding values were -9.1 (±0.5) kJ mol -1 and -124 (±10) J mol-1 K-1, respectively.

Original languageEnglish
Pages (from-to)247-252
Number of pages6
JournalMicroporous and Mesoporous Materials
Volume80
Issue number1-3
DOIs
StatePublished - 2005

    Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials

    Research areas

  • Adsorption thermodynamics, FTIR, Hydrogen, Zeolites, ZSM-5

ID: 13733546