Thermodynamics of hydrogen adsorption on the zeolite Ca-Y

Variable-temperature infrared spectroscopy was used for a thermodynamic study on hydrogen adsorption on the zeolite Ca-Y. Adsorption renders the H-H stretching mode infrared active, at 4078 cm(-1); and simultaneous measurement of IR absorbance and hydrogen equilibrium pressure, over a range of temperature, allowed standard adsorption enthalpy and entropy to be determined. They resulted to Delta H degrees = -15.0(+/- 1.0)kJ mol(-1) and Delta S degrees =-127(+/- 10)J mol(-1) K-1, respectively. These relatively high values of adsorption enthalpy and entropy are discussed in the broader context of corresponding data for other hydrogen adsorbents. (C) 2008 Elsevier B.V. All rights reserved.