Thermodynamic study of water adsorption in high-silica zeolites

Article Abstract:

The combined use of microcalorimetric and computational approaches are adopted to describe the mechanism of [H.sub.2] interaction with the acidic sites located within the proton-exchanged zeolites nanocavities, of both Lewis and Bronsted nature. The adsorption experimental enthalpies are compared to ab initio computed binding energies of [H.sub.2]O interacting with model sites simulating Lewis and Bronsted acidic sites and a variety of Si-OH species, either H-bonding interacting or isolated.

Analysis, Electric properties, Adsorption, Thermodynamics, Protons

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Molecular water on exposed A[l.sup.3+] cations is a source of acidity in silicoaluminas

Article Abstract:

A study using infrared spectroscopy and ab initio calculations provided evidence about the remarkable acidic nature of molecular water adsorbed at the surface of mesoporous MCM-41 silicoaluminas (MSA) with a ratio of Si/Al = 25. OH stretching and HOH bending modes of water adsorbed on coordinatively unsaturated Al ions at the surface of mesoporous version of silicoaluminas were detected for the first time using CO as a probe.

Italy, Aluminum Silicate, Water chemistry, Aluminum silicates, Chemical properties

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Can Cu+-exchanged zeolites store molecular hydrogen? An ab-initio periodic study compared with low temperature FTIR

Article Abstract:

Using the periodic CRYSTAL03 computer code with Hartree-Fock and the hybrid B3LYP Hamiltonians to characterize the structures and energetics of the Cu+ ion sitting preference and interaction with H2, Cu+-exchanges Si/Al 11:1 chabatize is studies ab initio. Chabatize has been selected because its small unit cell allows fully ab initio periodic calculations with good basis sets to be performed on commodity personal computers.

Electrochemistry, Chemical synthesis, Electrochemical reactions

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