FTIR spectroscopic and computational studies on hydrogen adsorption on the zeolite Li–FER

Abstract

The interaction, at a low temperature, between molecular hydrogen and the zeolite Li–FER was studied by means of variable temperature infrared spectroscopy and theoretical calculations using a periodic DFT model. The adsorbed dihydrogen molecule becomes infrared active, giving a characteristic IR absorption band (H–H stretching) at 4090 cm⁻¹. Three different Li⁺ site types with respect to H₂ adsorption were found in the zeolite, two of which adsorb H₂. Calculations showed a similar interaction energy for these two sites, which was found to agree with the experimentally determined value of standard adsorption enthalpy of ΔH⁰ = −4.1 (±0.8) kJ mol⁻¹. The results are discussed in the broader context of previously reported data for H₂ adsorption on Na–FER and K–FER.