Thermodynamics of hydrogen adsorption on the zeolite Li-ZSM-5

Thermodynamic characterisation of the adsorption process (at a low temperature) of clihydrogen on the zeolite Li-ZSM-5 was carried out by means of variable-temperature infrared spectroscopy, with the simultaneous measurement of temperature and equilibrium pressure. Adsorption renders the H-H stretching mode infrared active, at 4092 cm(-1`). The standard adsorption enthalpy and entropy resulted to be DeltaH(0) = -6.5(+/-0.5) kJ mol(-1) and DeltaS(0) = -90(5) J mol(-1) K-1, respectively. The adsorption enthalpy is significantly larger than the liquefaction heat, and this fact renders Li-ZSM-5 a potential cryoadsorbent for hydrogen storage. (C) 2003 Elsevier Science B.V. All rights reserved.